CA1333316C - Processes for microemulsion polymerization employing novel microemulsion systems - Google Patents
Processes for microemulsion polymerization employing novel microemulsion systemsInfo
- Publication number
- CA1333316C CA1333316C CA000584080A CA584080A CA1333316C CA 1333316 C CA1333316 C CA 1333316C CA 000584080 A CA000584080 A CA 000584080A CA 584080 A CA584080 A CA 584080A CA 1333316 C CA1333316 C CA 1333316C
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- CA
- Canada
- Prior art keywords
- phase
- microemulsion
- monomer
- surfactant
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000004530 micro-emulsion Substances 0.000 title claims abstract description 71
- 238000000034 method Methods 0.000 title claims abstract description 45
- 230000008569 process Effects 0.000 title claims abstract description 44
- 238000012703 microemulsion polymerization Methods 0.000 title description 7
- 239000000178 monomer Substances 0.000 claims abstract description 59
- 239000012530 fluid Substances 0.000 claims abstract description 55
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 39
- 239000000463 material Substances 0.000 claims abstract description 33
- 239000000693 micelle Substances 0.000 claims abstract description 31
- 239000003505 polymerization initiator Substances 0.000 claims abstract description 11
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 5
- HRPVXLWXLXDGHG-UHFFFAOYSA-N Acrylamide Chemical compound NC(=O)C=C HRPVXLWXLXDGHG-UHFFFAOYSA-N 0.000 claims description 66
- 239000004094 surface-active agent Substances 0.000 claims description 51
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 48
- 239000001294 propane Substances 0.000 claims description 24
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 23
- 238000006116 polymerization reaction Methods 0.000 claims description 23
- 239000002736 nonionic surfactant Substances 0.000 claims description 16
- 238000006243 chemical reaction Methods 0.000 claims description 15
- 239000003945 anionic surfactant Substances 0.000 claims description 13
- 150000001335 aliphatic alkanes Chemical class 0.000 claims description 12
- 239000000839 emulsion Substances 0.000 claims description 11
- 239000003999 initiator Substances 0.000 claims description 9
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 claims description 8
- 230000000379 polymerizing effect Effects 0.000 claims description 7
- FQPSGWSUVKBHSU-UHFFFAOYSA-N methacrylamide Chemical compound CC(=C)C(N)=O FQPSGWSUVKBHSU-UHFFFAOYSA-N 0.000 claims description 5
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 claims description 4
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 claims description 4
- XTXRWKRVRITETP-UHFFFAOYSA-N Vinyl acetate Chemical compound CC(=O)OC=C XTXRWKRVRITETP-UHFFFAOYSA-N 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 4
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 claims description 4
- 230000005855 radiation Effects 0.000 claims description 4
- 125000000391 vinyl group Chemical group [H]C([*])=C([H])[H] 0.000 claims description 4
- 229920002554 vinyl polymer Polymers 0.000 claims description 4
- BWGNESOTFCXPMA-UHFFFAOYSA-N Dihydrogen disulfide Chemical compound SS BWGNESOTFCXPMA-UHFFFAOYSA-N 0.000 claims description 2
- 125000000751 azo group Chemical group [*]N=N[*] 0.000 claims description 2
- 239000001273 butane Substances 0.000 claims description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 claims description 2
- 150000002978 peroxides Chemical class 0.000 claims description 2
- 230000002844 continuous effect Effects 0.000 claims 1
- 239000002563 ionic surfactant Substances 0.000 claims 1
- 239000012071 phase Substances 0.000 description 71
- 239000000203 mixture Substances 0.000 description 40
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 18
- 238000002474 experimental method Methods 0.000 description 11
- XLNZHTHIPQGEMX-UHFFFAOYSA-N ethane propane Chemical compound CCC.CCC.CC.CC XLNZHTHIPQGEMX-UHFFFAOYSA-N 0.000 description 10
- NMSBTWLFBGNKON-UHFFFAOYSA-N 2-(2-hexadecoxyethoxy)ethanol Chemical compound CCCCCCCCCCCCCCCCOCCOCCO NMSBTWLFBGNKON-UHFFFAOYSA-N 0.000 description 6
- WPMWEFXCIYCJSA-UHFFFAOYSA-N Tetraethylene glycol monododecyl ether Chemical compound CCCCCCCCCCCCOCCOCCOCCOCCO WPMWEFXCIYCJSA-UHFFFAOYSA-N 0.000 description 6
- 230000007423 decrease Effects 0.000 description 5
- 230000003993 interaction Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 230000000977 initiatory effect Effects 0.000 description 3
- 238000012688 inverse emulsion polymerization Methods 0.000 description 3
- 229920002401 polyacrylamide Polymers 0.000 description 3
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 2
- 238000013019 agitation Methods 0.000 description 2
- 239000013256 coordination polymer Substances 0.000 description 2
- 239000004064 cosurfactant Substances 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 238000007720 emulsion polymerization reaction Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000005191 phase separation Methods 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 230000002441 reversible effect Effects 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- 208000036366 Sensation of pressure Diseases 0.000 description 1
- 241000287181 Sturnus vulgaris Species 0.000 description 1
- ULUAUXLGCMPNKK-UHFFFAOYSA-N Sulfobutanedioic acid Chemical compound OC(=O)CC(C(O)=O)S(O)(=O)=O ULUAUXLGCMPNKK-UHFFFAOYSA-N 0.000 description 1
- 150000003926 acrylamides Chemical class 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 150000004945 aromatic hydrocarbons Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000010960 commercial process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- JROGBPMEKVAPEH-GXGBFOEMSA-N emetine dihydrochloride Chemical compound Cl.Cl.N1CCC2=CC(OC)=C(OC)C=C2[C@H]1C[C@H]1C[C@H]2C3=CC(OC)=C(OC)C=C3CCN2C[C@@H]1CC JROGBPMEKVAPEH-GXGBFOEMSA-N 0.000 description 1
- 238000004945 emulsification Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 229920006158 high molecular weight polymer Polymers 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- LRDFRRGEGBBSRN-UHFFFAOYSA-N isobutyronitrile Chemical compound CC(C)C#N LRDFRRGEGBBSRN-UHFFFAOYSA-N 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000002798 polar solvent Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- AVSXGQJYEFAQNK-UHFFFAOYSA-N prop-2-enamide;hydrate Chemical compound O.NC(=O)C=C AVSXGQJYEFAQNK-UHFFFAOYSA-N 0.000 description 1
- 238000010526 radical polymerization reaction Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- APSBXTVYXVQYAB-UHFFFAOYSA-M sodium docusate Chemical compound [Na+].CCCCC(CC)COC(=O)CC(S([O-])(=O)=O)C(=O)OCC(CC)CCCC APSBXTVYXVQYAB-UHFFFAOYSA-M 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- 241000894007 species Species 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000012546 transfer Methods 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 239000007762 w/o emulsion Substances 0.000 description 1
- NWONKYPBYAMBJT-UHFFFAOYSA-L zinc sulfate Chemical compound [Zn+2].[O-]S([O-])(=O)=O NWONKYPBYAMBJT-UHFFFAOYSA-L 0.000 description 1
Classifications
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
- A61K9/00—Medicinal preparations characterised by special physical form
- A61K9/10—Dispersions; Emulsions
- A61K9/107—Emulsions ; Emulsion preconcentrates; Micelles
- A61K9/1075—Microemulsions or submicron emulsions; Preconcentrates or solids thereof; Micelles, e.g. made of phospholipids or block copolymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D11/02—Solvent extraction of solids
- B01D11/0203—Solvent extraction of solids with a supercritical fluid
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/40—Mixing liquids with liquids; Emulsifying
- B01F23/41—Emulsifying
- B01F23/4105—Methods of emulsifying
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J10/00—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor
- B01J10/002—Chemical processes in general for reacting liquid with gaseous media other than in the presence of solid particles, or apparatus specially adapted therefor carried out in foam, aerosol or bubbles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
- B01J3/008—Processes carried out under supercritical conditions
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/14—Methods for preparing oxides or hydroxides in general
- C01B13/32—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
- C01B13/14—Methods for preparing oxides or hydroxides in general
- C01B13/32—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process
- C01B13/328—Methods for preparing oxides or hydroxides in general by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process by processes making use of emulsions, e.g. the kerosine process
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/16—Preparation of silica xerogels
- C01B33/163—Preparation of silica xerogels by hydrolysis of organosilicon compounds, e.g. ethyl orthosilicate
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F7/00—Compounds of aluminium
- C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
- C01F7/34—Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G3/00—Compounds of copper
- C01G3/02—Oxides; Hydroxides
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G5/00—Compounds of silver
- C01G5/02—Halides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/32—Polymerisation in water-in-oil emulsions
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K23/00—Use of substances as emulsifying, wetting, dispersing, or foam-producing agents
- C09K23/02—Alkyl sulfonates or sulfuric acid ester salts derived from monohydric alcohols
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/04—Specific aggregation state of one or more of the phases to be mixed
- B01F23/043—Mixing fluids or with fluids in a supercritical state, in supercritical conditions or variable density fluids
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
- B01F23/40—Mixing liquids with liquids; Emulsifying
- B01F23/41—Emulsifying
- B01F23/414—Emulsifying characterised by the internal structure of the emulsion
- B01F23/4143—Microemulsions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00054—Controlling or regulating the heat exchange system
- B01J2219/00056—Controlling or regulating the heat exchange system involving measured parameters
- B01J2219/00058—Temperature measurement
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00051—Controlling the temperature
- B01J2219/00054—Controlling or regulating the heat exchange system
- B01J2219/00056—Controlling or regulating the heat exchange system involving measured parameters
- B01J2219/00065—Pressure measurement
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J2219/00049—Controlling or regulating processes
- B01J2219/00191—Control algorithm
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S516/00—Colloid systems and wetting agents; subcombinations thereof; processes of
- Y10S516/924—Significant dispersive or manipulative operation or step in making or stabilizing colloid system
- Y10S516/925—Phase inversion
Abstract
This invention is directed to a microemulsion system comprising a first phase including a low-polarity fluid material which is a gas at standard temperature and pressure, and which has a cloud-point density. It also includes a second phase including a polar fluid, typically water, a monomer, preferably a monomer soluble in the polar fluid, and a microemulsion promoter for facilitating the formation of micelles including the monomer in the system. In the subject process, micelles including the monomer are formed in the first phase. A polymerization initiator is introduced into the micelles in the microemulsion system. The monomer is then polymerized in the micelles, preferably in the core of the micelle, to produce a polymeric material having a relatively high molecular weight.
Description
PROCESSES FOR MICROEMULSION POLYMERIZATION
EMPLOYING NOVEL MICROEMULSION SYSTEMS
BACKGROUND OF THE INVENTION
This invention relates to methods for the polymerization of monomers, and to novel microemulsion systems for conducting such polymerizations.
Emulsion polymerization is an important commercial process because, in contrast to the same free-radical polymerization performed in the bulk, molecular weight and reaction rate can be increased simultaneously.l Furthermore, the lower viscosity of an emulsion system compared to that of the corresponding bulk process provides better control over heat transfer. Commercial emulsion processes usually use a surfactant-water-monomer system which is stabilized by vigorous stirring. The dispersed phase contains micelles, approximately 10 to 50 nm in diameter, as well as monomer droplets. In the absence of agitation, these monomer droplets will coagulate and separate as a second phase. If, as is the usual practice,l a continuous-phase soluble initiator is used, polymerization commences at the micelle interface and proceeds within the micelles. During the reaction, monomer diffuses from the large droplets into the micelles. Exhaustion of these monomer reservoirs signals the end of the polymerization.
Recently " 2 ~ polymerization in microemulsions has been studied. In contrast to the emulsion system described above, a microemulsion is thermodynamically stable, and thus one-phase and optically clear in the absence of agitation. Microemulsion polymerization has been used to produce stable lattices with a very fine (approx. 50 nm) particle size.4 Most emulsion polymerization systems employ an oil-soluble monomer dispersed in an aqueous continuous d~
~r ~ 1 3333 1 ~
phase. Recent work2 8 describes polymerizing water-soluble monomers in an inverse emulsion (a water in oil emulsion). However, conventional inverse emulsions are even less stable than conventional water-in-oil emulsions,l. Although an inverse microemulsion polymerization is an efficient way to produce high molecular weight polymer, there remains the problem of separation of the polymer from a large volume of oil.
SUMMARY OF THE INVENTION
The processes and systems relating to microemulsions of the present invention overcomes the above problems associated with the prior art, and more particularly provide processes and systems for polymerizing a monomer, in which a microemulsion system is formed and employed.
The microemulsion system comprises a first phase including a low-polarity fluid material which is a gas at standard temperature and pressure, and which has a cloud-point density. It also includes a second phase including a polar fluid, typically water, a monomer, preferably a monomer soluble in the polar fluid, and a microemulsion promoter for facilitating the formation of micelles including the monomer in the system. In the subject process, micelles including the monomer are formed in the first phase.
A polymerization initiator is introduced into the micelles in the microemulsion system. The monomer is then polymerized in the micelles, preferably in the core of the micelle, to produce a polymeric material having a relatively high molecular weight. More specifically, polymeric product material preferably has a weight average molecular weight of at least about 100,000, and more preferably at least about 200,000.
Preferably, the weight average molecular weight can be up to about 1,000,000, and more preferably up to at ~ 3 ~
about 2,000,000, and most preferably up to about 5,000,000.
Moreover, the weight average molecular weight of the polymeric material polymerized at a temperature about the supercritical temperature of the fluid material is preferably at least 25~, more preferably at least 50~, and most preferably at least 100~ greater than the weight average molecular weight of the polymeric material produced under substantially the same reaction conditions except that the polymerization is conducted at a temperature below the supercritical temperature of the fluid material.
Supercritical fluids, materials at temperatures and pres-sures above their critical values, display physical prop-erties which are intermediate to those of liquids andgases.9 The density of a supercritical fluid, and conse-quently the whole range of density-dependent properties (viscosity, solvent power, dielectric constant, etc.) can be readily varied over more than an order of magnitude by varying pressure.
The microemulsion system of the present invention preferably comprises a substantially stable inverse emul-sion which includes a second phase comprising a substan-tially discontinuous phase and a first phase comprising a substantially continuous phase. The system can be main-tained at a pressure and temperature such that the density of the low-polarity fluid exceeds its cloud-point density thereof. Moreover, the polymerization is preferably conducted at a temperature which is at least equal to the supercritical temperature of the low-polarity fluid ma-terial.
The process of the present invention typically employs a water-soluble monomer. This water-soluble monomer generally comprises at least one of acrylamide, methacrylamide, acrylic acid, methacrylic acid, an acrylic acid salt, vinyl pyrolidone, and vinyl acetate.
B
- /
4 l 3333 ~ 6 However, the acrylamide and methacrylamide monomers are most preferred.
The subject microemulsion promoter generally comprises a surfactant. Particularly, the microemulsion promoter is one which is substantially soluble in the second phase. The microemulsion promoter preferably comprises at least one of a non-ionic surfactant and an anionic surfactant. Moreover, a non-ionic surfactant can be chosen which has an HLB of from about 5 to 10, preferab-ly 6 to 8, and most perferably from 6.5 to 7.5. Further-more, in some instances, the monomer can act as a microe-mulsion co-promoter. Typically this occurs when such co-promoter is a water-soluble monomer in the second phase.
It is preferred that the molar ratio of the microemulsion promoter to the polar fluid is at least about 1, more preferably at least about 3, and most preferably at least about 5. It is also preferred that the microemulsion promoter chosen substantially solubilizes the polar fluid at pressures up to about 500 bar.
The low-polarity fluid is preferably a non-polar fluid. The non-polar fluid material is preferably at least one lower alkane. More preferably, the fluid material is a lower alkane which is one of ethane, propane and butane.
The process typically includes a polymerization initiator capable of passing through the continuous phase into the discontinuous phase for catalyzing the polymeriz-ation of the monomer within the interstices of the micel-les. The polymerization initiator is typically activatedby at least one of thermal and radiation means. Further-more, the polymerization initiator preferably comprises at least one of an azo, peroxide, and disulfide initiator compound.
1 3~s316 Unexpectedly, in the process of the present invention, the pressure required to form the microemulsion system can be reduced as the amount of the second phase in the microemulsion system is increased. The volume fraction dispersal phase in the microemulsion system is defined as the total volume of the microemulsion promoter, the polar fluid and the monomer as a fraction of the total volume of the microemulsion system. As the volume fraction dispersed phase increases up to about 0.30, the clearing pressure is measured at various intervals by comparing the difference in pressure values at a volume fraction dispersed phase (VPFP) of 0.10 with pressure valve at a VPFP of 0.15 to 0.03, dividing that value by the VPFP at 0.10, and multi-plying that quantity by 100, the reduction in pressure was at least 20~, more preferably at least 25~, and most preferably at least 30~.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment which proceeds with reference to the drawlngs .
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graphical representation of cloud point curves of an anionic surfactant (AOT) and a super-critical fluid (propane) system with a water to surfactant ratio (W) of 5.0 for monomer (acrylamide) to surfactant ratios up to 0.40. (See Table 1 for data.) FIG. 2 is a graphical representation of the critical temperature of ethane/propane mixtures versus composition. (See Table 2 for data.) FIG. 3 is a graphical representation of cloud point curves of non-ionic surfactant (Brij 52 ("B52")/Brij 30 ("B30) 80/20 by weight mixtures, having a water to surfactant ratio of 5.0, a monomer (acrylamide) to surfactant ratio of 1.0, a total dispersed phase volume fraction of 0.136, at seven continuous phase ethane concentrations (weight %).
(See Table 3 for data.) FIG. 4 is a graphical representation of data from FIG. 3 replotted as density of continuous phase at cloud point versus temperature; the symbols in FIG. 4 being the same as in FIG. 3. (See Table 4 for data.) FIG. 5 is a graphical representation of the solubility of an 80/20 by weight non-ionic surfactant (B52/B30) mixture in an 80.4/19.6 supercritical fluid (ethane-propane) blend at 500 bar versus temperature.
(See Table 5 for data.) FIG. 6 is a graphical representation of a water to non-ionic surfactant (B52/B30) ratio of 80.4/19.6 with a supercritical fluid (ethane-propane) mixture at 30C
and 500 bar versus monomer (acrylamide) to surfactant ratio. (See Table 6 for data.) FIG. 7 is a graphical representation of the cloud point of non-ionic surfactant (B52/B30) in 80.4/19.6 supercritical fluid (ethane-propane) mixtures with a water to surfactant ratio of 5.0 and a monomer (acrylamide) to surfactant ratio of 1.0 versus dispersed phase volume fraction FIG. 8 is a graphical representation of cloud point curves of non-ionic surfactant (B52/B30) in 80.4/19.6 supercritical fluid (ethane-propane) mixtures with a water to surfactant ratio of 5.0 and a monomer (acrylamide) to surfactant ratio of 1.0 at five dispersed phase volume fractions.
FIG. 9 is a graphical representation of the data from FIG. 10 replotted versus continuous phase density.
FIG. 10 is a graphical representation of the cloud point temperatures of non-ionic surfactant (B52/B30) mixtures in 80.4/19.6 supercritical fluid (ethane-propane) mixtures with a water/surfactant ratio of 5.0 and a monomer (acrylamide) to surfactant ratio of 1.0 versus dispersed phase volume fraction.
FIG. 11 is the graphical representation of FIG. 2 including points representing the ethane-propane mixture levels employed in the experiments set forth in Example 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIGS. 1-11, various properties of the microemulsion system of the present invention are graphically represented which define certain relationships between the components forming the subiect system. Exemplary component materials were used in these experiments to produce the data which forms such graphical representations. Such materials include nonionic surfactants Brij 52*(B52) and Brij 30*
(B30) which were obtained from the Sigma Chemical Company and used as received. Although nominally C16E2 and C12E4, respectively, these surfactants are each composed of a mixture of species of differing chain lengths. Furthermore, Aerosol AOT,* i.e., sodium bist2-ethyl hexyl) sulfosuccinate, was obtained from Fluka Chemical (purum grade) and purified according to - Kotlarchyk, et al.ll Acrylamide (AM) was obtained from the Aldrich Chemical Company (Gold Label 99~%) and recrystallized twice from chloroform. Water was doubly de-ionized. Propane was obtained from Union Carbide Linde Division (CP Grade), ethane from Air Products (CP
Grade), and all were used without further purification.
Phase transitions were observed visually using a high pressure view cell (volume = 47 cm3), capable of pressures to 600 bar, whose design has been previously described. Material was introduced to the magnetically stirred call which was then sealed and * trade-mark A
~ 3~3 1 ~
pressurized with the fluid of choice using a Varian 8500 syringe pump. Gas mixtures were prepared by weight (composition +/- .25%) in a 400 cm3 lecture bottle, stirred for 15 minutes, then transferred to the syringe pump head. Temperature in the cell was controlled to within 0.1C using an Omega thermocouple-temperature programmer. Pressure was measured using a Precise Sensor 0 to 10,000 psi transducer and readout calibrated to within +/- 10 psi using a Heise Bourdon-tube gauge.
Regarding the microemulsion of this invention, themost efficient surfactant for the polymerization of a particular monomer is a function of the choice of the continuous phase, the monomer structure, and the polar solvent content. The correct choice is not necessarily apparent, particularly in the case where the continuous phase is a supercritical fluid. A study of the inverse emulsion polymerization of acrylamide (AM) within a toluene continuous phase,l4 below the cloud point density of toluene, showed that acrylamide acts as a co-surfactant with AOT.
However, since the critical temperature of aromatic hydrocarbons benzene and toluene are about 250-300C, the surfactant would be thermally destroyed if such polymerization were conducted about that Tc.
In the AOT/water/propane system, of the present invention, the addition of small amounts of acrylamide significantly reduces the size of the one-phase region (see FIG. 1). By contrast, in the absence of acrylamide, a stable microemulsion at a water/surfactant ratio of 5 can be formed at pressures as low as 10 bar in propane (at 25C). For AM to function as a co-surfactant, it should partition preferentially to the interface. In the AOT/toluene system, the attraction of the AM for the AOT head group, the toluene continuous phase, and the surfactant tails is therefore assumed to be appropriately balanced. In the AOT/alkane system, the AM is apparently biased towards the AOT headgroup (solubility of AM in alkanes is extremely low)12 and thus may remain largely associated with the core region.
In addition to the effects upon phase behavior, the presence of AOT, despite purification, initiates polymerization in acrylamide. Thus, while AOT has been the subject of numerous studies of reverse micelles in both sub- and supercritical fluids, it was not considered the best choice for acrylamide-containing micelles in an alkane continuous phase.
The empirical HLB processl5'16 was used to guide selection of an appropriate non-ionic surfactant. HLB, a means by which to categorize nonionic surfactants, normalizes the weight fraction of hydrophilic groups in a molecule to a 0 to 20 scale. While HLB is usually calculated from the surfactant structure alone, the behavior of a surfactant in an emulsion is governed by the continuous phase composition and monomer concentration as well.17'22 This is because the emulsion stability depends on the proper balance of lipophile-oil and hydrophile-water interactions.38 In addition, as mentioned above, acrylamide can act as a cosurfactant when particular oil-surfactant combinations are used. Preliminary screening of mixtures of the Brij 52 and Brij 30 (B52/B30) nonionic surfactants (which cover an HLB range of approximately 6 to 12) in non-supercritical pentane/AM/water system at atmospheric pressure showed the highest allowable AM
concentrations were attained at an 80/20 ratio of the surfactants, a calculated HLB value of approximately 7.5. Similar results were obtained in liquid propane at 25C and 50 bar.
To maximize the amount of product yielded by inverse emulsion polymerization, it would be desirable to solubilize as much acrylamide as possible in the microemulsion while using the minimum amount of surfactant. Because water is merely a solvent which must eventually be removed from the product, the ideal water content of the microemulsion would be zero.
The solubility of either acrylamide or water in ethane/propane mixtures is extremely low.12'13 The solubility of the surfactant mixture B52/B30 is also low. However, mixing acrylamide with the B52/B30 blend allows significantly larger amounts of both components to be solubilized in the alkane continuous phase so that the acrylamide monomer is a co-surfactant in this system. The B52/B30 mixture will solubilize acrylamide up to a AM:molar ratio of 1:4; larger ratios of AM lead to precipitation of an apparently solid phase. This acrylamide concentration is lower by a factor of 5 to 10 than that used by Leong and Candau2 in the inverse microemulsion polymerization of acrylamide within a toluene continuous phase.
The addition of water significantly increases the amount of acrylamide which can be solubilized by the B52/B30/ethane/propane system. Accurate determination of cloud point curves of microemulsions with AM levels higher than 1.5 is difficult since the reddish-purple color which is evident upon clearing (see previous section) darkens significantly as the acrylamide level increases .
Although water allows for greater uptake of acrylamide by the microemulsion, water alone (AM=0) will not produce a one-phase system with the Brij 52/30 blend in an ethane/propane continuous phase.
Acrylamide behaves as a co-surfactant with the B52/B30 blend, as evidenced by the results in FIG. 6. When more than the maximum allowable water level is added at a particular AM content, the system becomes turbid followed by the appearance of small droplets on the 1 ~33 1 6 view cell windows (i.e., phase separation). Co-surfactant behavior by acrylamide depends both on the choice of continuous phase and primary surfactant structure.
As the water concentration is raised at constant AM ratio, the clearing pressure decreases. The decrease is approximately 10 to 15 bar for each increase of 1.0 in the water/surfactant ratio up to the maximum water ratio as shown in FIG. 6.
In the application of these microemulsion systems to polymerization processes, it would be desirable to maximize polymer yield, which can be accomplished by r~x;m; zing the acrylamide ratio at constant surfactant loading. In addition, of course, the acrylamide ratio (as well as the water ratio) to the surfactant can be fixed and the total amount of surfactant in the system increased. Therefore, the effect of total dispersed phase concentration on the phase behavior was investigated. The dispersed phase concentration (the volume dispersed fraction) is equal to the total volume of surfactants + monomer + water divided by the total volume.
Results shown in FIG. 7 reveal that increasing the dispersed phase volume fraction significantly reduces the pressure required to form a stable microemulsion.
At a volume fraction of 0.09, a one phase system will not form at any pressure up to 550 bar, whereas increasing volume fraction to 0.15 will produce a stable microemulsion at less than 300 bar. Apparently, specific interactions between micelles contribute to this effect, as shown by the cloud point curves in FIGS. 8 and 9.
If the temperature is increased to a certain point, these microemulsion systems will remain turbid above the pressure at which they become one phase.
This ceiling temperature decreases as the dispersed ~ 3333 ~ 6 phase volume fraction increases (see FIG. 10).
Apparently, a certain degree of micelle-micelle interaction is useful in improving the stability of this microemulsion (FIGS. 7-9) but if such interactions become too strong, as by raising the temperature as shown in FIG. 10, clustering and finally phase separation can occur. Thus a proper balance between micelle-micelle and micelle-continuous phase interactions must be achieved for maximum stability.
In order to broaden the temperature range in which a microemulsion acrylamide polymerization could be conducted within a supercritical alkane continuous phase, the phase behavior of the Brij mixture/water/AM
system in mixtures of propane (Tc = 97C) and ethane (Tc = 32C) was investigated. The ethane/propane mixture displays near-ideal mixture behaviorl3'19 as evidenced by the linearity in the critical temperature-concentration curve in FIG. 6. In this series of experiments the water concentration was fixed at W=5.0 and that for the acrylamide at 1.0 (water and acrylamide concentrations are reported as molar ratios to the surfactants; the nominal molecular weights of 330 for Brij 52 and 360 for Brij 30 were used. The volume fraction of the dispersed phase (volume of surfactants + water + acrylamide divided by the total system volume) in this series of experiments was 0.136.
The phase behavior in FIG. 5 is given in terms of clearing points (or cloud points where the one phase region is above each curve), i.e., the pressure where the system becomes one phase was determined. Clearing points for the system under investigation here can easily be determined to within 1-2 bar using the view cell. As the pressure in the view cell is raised to the clearing point, the B52/B30/AM/water system turns from opaque to a transparent reddish-purple color. As pressure is increased beyond the clearing point, the -1 3~33 1 6 color changes progressively to red-orange to orange to yellow (the color changes are reversible).
The cloud point data in FIG. 8 reveal a series of curves which are essentially parallel and shifted to higher pressures as the amount of ethane in the mixture increases. These data are replotted as cloud point density versus temperature in FIG. 9. Densities for pure ethane and propane were taken from the literature, those for the 80.4/19.6 mixture were measured, and those for the other mixtures were calculated using the Starling variant of the Benedict-Webb-Rubin equation of state with literature values for the ethane and propane parameters.18) FIG. 6 also suggests that increasing the temperature increases the stability of the emulsion since the continuous phase density at the clearing point decreases. However, this trend does not continue indefinitely; above 72C this system is one phase yet turbid. Decreasing stability of microemulsions as temperature increases has been observed frequently in systems at atmospheric pressure.23 24 These data show that for these lower alkanes it is the bulk property of continuous phase density rather than the structure of the fluid, that governs the phase behavior of the surfactant mixture/AM/water/ethane/propane system. Thus, a microemulsion polymerization reaction can be performed in these systems over a wide range in temperature, yet close to the continuous phase critical point, by varying the amount of ethane in the mixture (see FIGS.
EMPLOYING NOVEL MICROEMULSION SYSTEMS
BACKGROUND OF THE INVENTION
This invention relates to methods for the polymerization of monomers, and to novel microemulsion systems for conducting such polymerizations.
Emulsion polymerization is an important commercial process because, in contrast to the same free-radical polymerization performed in the bulk, molecular weight and reaction rate can be increased simultaneously.l Furthermore, the lower viscosity of an emulsion system compared to that of the corresponding bulk process provides better control over heat transfer. Commercial emulsion processes usually use a surfactant-water-monomer system which is stabilized by vigorous stirring. The dispersed phase contains micelles, approximately 10 to 50 nm in diameter, as well as monomer droplets. In the absence of agitation, these monomer droplets will coagulate and separate as a second phase. If, as is the usual practice,l a continuous-phase soluble initiator is used, polymerization commences at the micelle interface and proceeds within the micelles. During the reaction, monomer diffuses from the large droplets into the micelles. Exhaustion of these monomer reservoirs signals the end of the polymerization.
Recently " 2 ~ polymerization in microemulsions has been studied. In contrast to the emulsion system described above, a microemulsion is thermodynamically stable, and thus one-phase and optically clear in the absence of agitation. Microemulsion polymerization has been used to produce stable lattices with a very fine (approx. 50 nm) particle size.4 Most emulsion polymerization systems employ an oil-soluble monomer dispersed in an aqueous continuous d~
~r ~ 1 3333 1 ~
phase. Recent work2 8 describes polymerizing water-soluble monomers in an inverse emulsion (a water in oil emulsion). However, conventional inverse emulsions are even less stable than conventional water-in-oil emulsions,l. Although an inverse microemulsion polymerization is an efficient way to produce high molecular weight polymer, there remains the problem of separation of the polymer from a large volume of oil.
SUMMARY OF THE INVENTION
The processes and systems relating to microemulsions of the present invention overcomes the above problems associated with the prior art, and more particularly provide processes and systems for polymerizing a monomer, in which a microemulsion system is formed and employed.
The microemulsion system comprises a first phase including a low-polarity fluid material which is a gas at standard temperature and pressure, and which has a cloud-point density. It also includes a second phase including a polar fluid, typically water, a monomer, preferably a monomer soluble in the polar fluid, and a microemulsion promoter for facilitating the formation of micelles including the monomer in the system. In the subject process, micelles including the monomer are formed in the first phase.
A polymerization initiator is introduced into the micelles in the microemulsion system. The monomer is then polymerized in the micelles, preferably in the core of the micelle, to produce a polymeric material having a relatively high molecular weight. More specifically, polymeric product material preferably has a weight average molecular weight of at least about 100,000, and more preferably at least about 200,000.
Preferably, the weight average molecular weight can be up to about 1,000,000, and more preferably up to at ~ 3 ~
about 2,000,000, and most preferably up to about 5,000,000.
Moreover, the weight average molecular weight of the polymeric material polymerized at a temperature about the supercritical temperature of the fluid material is preferably at least 25~, more preferably at least 50~, and most preferably at least 100~ greater than the weight average molecular weight of the polymeric material produced under substantially the same reaction conditions except that the polymerization is conducted at a temperature below the supercritical temperature of the fluid material.
Supercritical fluids, materials at temperatures and pres-sures above their critical values, display physical prop-erties which are intermediate to those of liquids andgases.9 The density of a supercritical fluid, and conse-quently the whole range of density-dependent properties (viscosity, solvent power, dielectric constant, etc.) can be readily varied over more than an order of magnitude by varying pressure.
The microemulsion system of the present invention preferably comprises a substantially stable inverse emul-sion which includes a second phase comprising a substan-tially discontinuous phase and a first phase comprising a substantially continuous phase. The system can be main-tained at a pressure and temperature such that the density of the low-polarity fluid exceeds its cloud-point density thereof. Moreover, the polymerization is preferably conducted at a temperature which is at least equal to the supercritical temperature of the low-polarity fluid ma-terial.
The process of the present invention typically employs a water-soluble monomer. This water-soluble monomer generally comprises at least one of acrylamide, methacrylamide, acrylic acid, methacrylic acid, an acrylic acid salt, vinyl pyrolidone, and vinyl acetate.
B
- /
4 l 3333 ~ 6 However, the acrylamide and methacrylamide monomers are most preferred.
The subject microemulsion promoter generally comprises a surfactant. Particularly, the microemulsion promoter is one which is substantially soluble in the second phase. The microemulsion promoter preferably comprises at least one of a non-ionic surfactant and an anionic surfactant. Moreover, a non-ionic surfactant can be chosen which has an HLB of from about 5 to 10, preferab-ly 6 to 8, and most perferably from 6.5 to 7.5. Further-more, in some instances, the monomer can act as a microe-mulsion co-promoter. Typically this occurs when such co-promoter is a water-soluble monomer in the second phase.
It is preferred that the molar ratio of the microemulsion promoter to the polar fluid is at least about 1, more preferably at least about 3, and most preferably at least about 5. It is also preferred that the microemulsion promoter chosen substantially solubilizes the polar fluid at pressures up to about 500 bar.
The low-polarity fluid is preferably a non-polar fluid. The non-polar fluid material is preferably at least one lower alkane. More preferably, the fluid material is a lower alkane which is one of ethane, propane and butane.
The process typically includes a polymerization initiator capable of passing through the continuous phase into the discontinuous phase for catalyzing the polymeriz-ation of the monomer within the interstices of the micel-les. The polymerization initiator is typically activatedby at least one of thermal and radiation means. Further-more, the polymerization initiator preferably comprises at least one of an azo, peroxide, and disulfide initiator compound.
1 3~s316 Unexpectedly, in the process of the present invention, the pressure required to form the microemulsion system can be reduced as the amount of the second phase in the microemulsion system is increased. The volume fraction dispersal phase in the microemulsion system is defined as the total volume of the microemulsion promoter, the polar fluid and the monomer as a fraction of the total volume of the microemulsion system. As the volume fraction dispersed phase increases up to about 0.30, the clearing pressure is measured at various intervals by comparing the difference in pressure values at a volume fraction dispersed phase (VPFP) of 0.10 with pressure valve at a VPFP of 0.15 to 0.03, dividing that value by the VPFP at 0.10, and multi-plying that quantity by 100, the reduction in pressure was at least 20~, more preferably at least 25~, and most preferably at least 30~.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment which proceeds with reference to the drawlngs .
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a graphical representation of cloud point curves of an anionic surfactant (AOT) and a super-critical fluid (propane) system with a water to surfactant ratio (W) of 5.0 for monomer (acrylamide) to surfactant ratios up to 0.40. (See Table 1 for data.) FIG. 2 is a graphical representation of the critical temperature of ethane/propane mixtures versus composition. (See Table 2 for data.) FIG. 3 is a graphical representation of cloud point curves of non-ionic surfactant (Brij 52 ("B52")/Brij 30 ("B30) 80/20 by weight mixtures, having a water to surfactant ratio of 5.0, a monomer (acrylamide) to surfactant ratio of 1.0, a total dispersed phase volume fraction of 0.136, at seven continuous phase ethane concentrations (weight %).
(See Table 3 for data.) FIG. 4 is a graphical representation of data from FIG. 3 replotted as density of continuous phase at cloud point versus temperature; the symbols in FIG. 4 being the same as in FIG. 3. (See Table 4 for data.) FIG. 5 is a graphical representation of the solubility of an 80/20 by weight non-ionic surfactant (B52/B30) mixture in an 80.4/19.6 supercritical fluid (ethane-propane) blend at 500 bar versus temperature.
(See Table 5 for data.) FIG. 6 is a graphical representation of a water to non-ionic surfactant (B52/B30) ratio of 80.4/19.6 with a supercritical fluid (ethane-propane) mixture at 30C
and 500 bar versus monomer (acrylamide) to surfactant ratio. (See Table 6 for data.) FIG. 7 is a graphical representation of the cloud point of non-ionic surfactant (B52/B30) in 80.4/19.6 supercritical fluid (ethane-propane) mixtures with a water to surfactant ratio of 5.0 and a monomer (acrylamide) to surfactant ratio of 1.0 versus dispersed phase volume fraction FIG. 8 is a graphical representation of cloud point curves of non-ionic surfactant (B52/B30) in 80.4/19.6 supercritical fluid (ethane-propane) mixtures with a water to surfactant ratio of 5.0 and a monomer (acrylamide) to surfactant ratio of 1.0 at five dispersed phase volume fractions.
FIG. 9 is a graphical representation of the data from FIG. 10 replotted versus continuous phase density.
FIG. 10 is a graphical representation of the cloud point temperatures of non-ionic surfactant (B52/B30) mixtures in 80.4/19.6 supercritical fluid (ethane-propane) mixtures with a water/surfactant ratio of 5.0 and a monomer (acrylamide) to surfactant ratio of 1.0 versus dispersed phase volume fraction.
FIG. 11 is the graphical representation of FIG. 2 including points representing the ethane-propane mixture levels employed in the experiments set forth in Example 1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring to FIGS. 1-11, various properties of the microemulsion system of the present invention are graphically represented which define certain relationships between the components forming the subiect system. Exemplary component materials were used in these experiments to produce the data which forms such graphical representations. Such materials include nonionic surfactants Brij 52*(B52) and Brij 30*
(B30) which were obtained from the Sigma Chemical Company and used as received. Although nominally C16E2 and C12E4, respectively, these surfactants are each composed of a mixture of species of differing chain lengths. Furthermore, Aerosol AOT,* i.e., sodium bist2-ethyl hexyl) sulfosuccinate, was obtained from Fluka Chemical (purum grade) and purified according to - Kotlarchyk, et al.ll Acrylamide (AM) was obtained from the Aldrich Chemical Company (Gold Label 99~%) and recrystallized twice from chloroform. Water was doubly de-ionized. Propane was obtained from Union Carbide Linde Division (CP Grade), ethane from Air Products (CP
Grade), and all were used without further purification.
Phase transitions were observed visually using a high pressure view cell (volume = 47 cm3), capable of pressures to 600 bar, whose design has been previously described. Material was introduced to the magnetically stirred call which was then sealed and * trade-mark A
~ 3~3 1 ~
pressurized with the fluid of choice using a Varian 8500 syringe pump. Gas mixtures were prepared by weight (composition +/- .25%) in a 400 cm3 lecture bottle, stirred for 15 minutes, then transferred to the syringe pump head. Temperature in the cell was controlled to within 0.1C using an Omega thermocouple-temperature programmer. Pressure was measured using a Precise Sensor 0 to 10,000 psi transducer and readout calibrated to within +/- 10 psi using a Heise Bourdon-tube gauge.
Regarding the microemulsion of this invention, themost efficient surfactant for the polymerization of a particular monomer is a function of the choice of the continuous phase, the monomer structure, and the polar solvent content. The correct choice is not necessarily apparent, particularly in the case where the continuous phase is a supercritical fluid. A study of the inverse emulsion polymerization of acrylamide (AM) within a toluene continuous phase,l4 below the cloud point density of toluene, showed that acrylamide acts as a co-surfactant with AOT.
However, since the critical temperature of aromatic hydrocarbons benzene and toluene are about 250-300C, the surfactant would be thermally destroyed if such polymerization were conducted about that Tc.
In the AOT/water/propane system, of the present invention, the addition of small amounts of acrylamide significantly reduces the size of the one-phase region (see FIG. 1). By contrast, in the absence of acrylamide, a stable microemulsion at a water/surfactant ratio of 5 can be formed at pressures as low as 10 bar in propane (at 25C). For AM to function as a co-surfactant, it should partition preferentially to the interface. In the AOT/toluene system, the attraction of the AM for the AOT head group, the toluene continuous phase, and the surfactant tails is therefore assumed to be appropriately balanced. In the AOT/alkane system, the AM is apparently biased towards the AOT headgroup (solubility of AM in alkanes is extremely low)12 and thus may remain largely associated with the core region.
In addition to the effects upon phase behavior, the presence of AOT, despite purification, initiates polymerization in acrylamide. Thus, while AOT has been the subject of numerous studies of reverse micelles in both sub- and supercritical fluids, it was not considered the best choice for acrylamide-containing micelles in an alkane continuous phase.
The empirical HLB processl5'16 was used to guide selection of an appropriate non-ionic surfactant. HLB, a means by which to categorize nonionic surfactants, normalizes the weight fraction of hydrophilic groups in a molecule to a 0 to 20 scale. While HLB is usually calculated from the surfactant structure alone, the behavior of a surfactant in an emulsion is governed by the continuous phase composition and monomer concentration as well.17'22 This is because the emulsion stability depends on the proper balance of lipophile-oil and hydrophile-water interactions.38 In addition, as mentioned above, acrylamide can act as a cosurfactant when particular oil-surfactant combinations are used. Preliminary screening of mixtures of the Brij 52 and Brij 30 (B52/B30) nonionic surfactants (which cover an HLB range of approximately 6 to 12) in non-supercritical pentane/AM/water system at atmospheric pressure showed the highest allowable AM
concentrations were attained at an 80/20 ratio of the surfactants, a calculated HLB value of approximately 7.5. Similar results were obtained in liquid propane at 25C and 50 bar.
To maximize the amount of product yielded by inverse emulsion polymerization, it would be desirable to solubilize as much acrylamide as possible in the microemulsion while using the minimum amount of surfactant. Because water is merely a solvent which must eventually be removed from the product, the ideal water content of the microemulsion would be zero.
The solubility of either acrylamide or water in ethane/propane mixtures is extremely low.12'13 The solubility of the surfactant mixture B52/B30 is also low. However, mixing acrylamide with the B52/B30 blend allows significantly larger amounts of both components to be solubilized in the alkane continuous phase so that the acrylamide monomer is a co-surfactant in this system. The B52/B30 mixture will solubilize acrylamide up to a AM:molar ratio of 1:4; larger ratios of AM lead to precipitation of an apparently solid phase. This acrylamide concentration is lower by a factor of 5 to 10 than that used by Leong and Candau2 in the inverse microemulsion polymerization of acrylamide within a toluene continuous phase.
The addition of water significantly increases the amount of acrylamide which can be solubilized by the B52/B30/ethane/propane system. Accurate determination of cloud point curves of microemulsions with AM levels higher than 1.5 is difficult since the reddish-purple color which is evident upon clearing (see previous section) darkens significantly as the acrylamide level increases .
Although water allows for greater uptake of acrylamide by the microemulsion, water alone (AM=0) will not produce a one-phase system with the Brij 52/30 blend in an ethane/propane continuous phase.
Acrylamide behaves as a co-surfactant with the B52/B30 blend, as evidenced by the results in FIG. 6. When more than the maximum allowable water level is added at a particular AM content, the system becomes turbid followed by the appearance of small droplets on the 1 ~33 1 6 view cell windows (i.e., phase separation). Co-surfactant behavior by acrylamide depends both on the choice of continuous phase and primary surfactant structure.
As the water concentration is raised at constant AM ratio, the clearing pressure decreases. The decrease is approximately 10 to 15 bar for each increase of 1.0 in the water/surfactant ratio up to the maximum water ratio as shown in FIG. 6.
In the application of these microemulsion systems to polymerization processes, it would be desirable to maximize polymer yield, which can be accomplished by r~x;m; zing the acrylamide ratio at constant surfactant loading. In addition, of course, the acrylamide ratio (as well as the water ratio) to the surfactant can be fixed and the total amount of surfactant in the system increased. Therefore, the effect of total dispersed phase concentration on the phase behavior was investigated. The dispersed phase concentration (the volume dispersed fraction) is equal to the total volume of surfactants + monomer + water divided by the total volume.
Results shown in FIG. 7 reveal that increasing the dispersed phase volume fraction significantly reduces the pressure required to form a stable microemulsion.
At a volume fraction of 0.09, a one phase system will not form at any pressure up to 550 bar, whereas increasing volume fraction to 0.15 will produce a stable microemulsion at less than 300 bar. Apparently, specific interactions between micelles contribute to this effect, as shown by the cloud point curves in FIGS. 8 and 9.
If the temperature is increased to a certain point, these microemulsion systems will remain turbid above the pressure at which they become one phase.
This ceiling temperature decreases as the dispersed ~ 3333 ~ 6 phase volume fraction increases (see FIG. 10).
Apparently, a certain degree of micelle-micelle interaction is useful in improving the stability of this microemulsion (FIGS. 7-9) but if such interactions become too strong, as by raising the temperature as shown in FIG. 10, clustering and finally phase separation can occur. Thus a proper balance between micelle-micelle and micelle-continuous phase interactions must be achieved for maximum stability.
In order to broaden the temperature range in which a microemulsion acrylamide polymerization could be conducted within a supercritical alkane continuous phase, the phase behavior of the Brij mixture/water/AM
system in mixtures of propane (Tc = 97C) and ethane (Tc = 32C) was investigated. The ethane/propane mixture displays near-ideal mixture behaviorl3'19 as evidenced by the linearity in the critical temperature-concentration curve in FIG. 6. In this series of experiments the water concentration was fixed at W=5.0 and that for the acrylamide at 1.0 (water and acrylamide concentrations are reported as molar ratios to the surfactants; the nominal molecular weights of 330 for Brij 52 and 360 for Brij 30 were used. The volume fraction of the dispersed phase (volume of surfactants + water + acrylamide divided by the total system volume) in this series of experiments was 0.136.
The phase behavior in FIG. 5 is given in terms of clearing points (or cloud points where the one phase region is above each curve), i.e., the pressure where the system becomes one phase was determined. Clearing points for the system under investigation here can easily be determined to within 1-2 bar using the view cell. As the pressure in the view cell is raised to the clearing point, the B52/B30/AM/water system turns from opaque to a transparent reddish-purple color. As pressure is increased beyond the clearing point, the -1 3~33 1 6 color changes progressively to red-orange to orange to yellow (the color changes are reversible).
The cloud point data in FIG. 8 reveal a series of curves which are essentially parallel and shifted to higher pressures as the amount of ethane in the mixture increases. These data are replotted as cloud point density versus temperature in FIG. 9. Densities for pure ethane and propane were taken from the literature, those for the 80.4/19.6 mixture were measured, and those for the other mixtures were calculated using the Starling variant of the Benedict-Webb-Rubin equation of state with literature values for the ethane and propane parameters.18) FIG. 6 also suggests that increasing the temperature increases the stability of the emulsion since the continuous phase density at the clearing point decreases. However, this trend does not continue indefinitely; above 72C this system is one phase yet turbid. Decreasing stability of microemulsions as temperature increases has been observed frequently in systems at atmospheric pressure.23 24 These data show that for these lower alkanes it is the bulk property of continuous phase density rather than the structure of the fluid, that governs the phase behavior of the surfactant mixture/AM/water/ethane/propane system. Thus, a microemulsion polymerization reaction can be performed in these systems over a wide range in temperature, yet close to the continuous phase critical point, by varying the amount of ethane in the mixture (see FIGS.
2-4).
One of the independent variables is the choice of initiator, and consequently, the polymerization temperature. Initiation in a true inverse emulsion or microemulsion polymerization occurs in the continuous phase, usually due to degradation of an oil-soluble -1 3~33 1 6 compound. The rate at which these compounds produce radicals is temperature-dependent. A variety of free-radical initiators are available thus allowing reaction to proceed at a reasonable rate at temperatures from 50 to 120C. However, trace oxygen will prompt thermal initiation at higher temperatures, which, in the interests of good control over the reaction, is undesirable. Application of radiation will permit a fast reaction at lower temperatures, and can even preclude the need for a chemical initiator, but again could lead to initiation at sites other than in the continuous phase. Therefore, the initiator azo bisisobutyrnitrile (AIBN), which is usually used at temperatures between 50 and 70C,l was chosen. In order to obtain the process advantages inherent in using a supercritical continuous phase while minimizing the required operating pressure, it would be desirable to run the polymerization reaction as close to the critical temperature of the fluid as possible.
Fortunately, rather than searching for a fluid with a critical temperature in the 50-70C range, a mixture of ethane and propane can be used. The phase behavior of this microemulsion system in ethane/propane mixtures appears to depend on the fluid density, and not on the fluid structure. If the polymerization is to be run in the temperature range of 50-70C, while remaining approximately 5C above the continuous phase Tc, the alkane mixture should be 50 to 80 weight percent ethane (see FIG. 6).
Setting the reaction temperature will also determine the maximum dispersed phase volume fraction which will permit a transparent, stable microemulsion.
As shown in FIG. 12, the ceiling temperature for stability of this microemulsion system decreases sharply as the dispersed phase volume fraction is increased. The minimum dispersed phase volume fraction t 3333 1 6 is set by the selection of the maximum operating pressure allowed for a given reaction vessel. Results in FIG. 7 show the surprising result that the clearing pressure for this microemulsion system increases rapidly below approximately 10%. Thus, once the maximum and minimum volume fractions are set, the actual volume fraction for the reaction can be chosen, and thus the operating pressure range (between the clearing pressure and the safe maximum for the reaction vessel).
The selection of acrylamide and water concentrations are also regulated by the phase behavior. Because acrylamide is a cosurfactant in the non-ionic surfactant-water-ethane/propane system, as the acrylamide is consumed during the polymerization, a point may be reached where the microemulsion will become turbid and begin to phase-separate. This situation can be postponed by setting the acrylamide ratio to 1.25, which is at the maximum of the AM-water curve (FIG. 11).
Example 1 Experiments were conducted in which an acrylamide monomer was polymerized according to the process of the present invention, under the same reaction conditions, except at different ethane to propane ratios. This resulted in one experiment being conducted above the supercritical temperature of ethane-propane mixture and the other experiment being conducted at near the supercritical temperature of the ethane-propane mixture. Clearly, both reactions exceeded the cloud point density of the ethane-propane low-polarity fluid mixture.
The experimental procedure for each of these processes is as follows:
The processes were all run in a 47cc high pressure view cell at 60C. 3.622 grams of Brij 52 and 0.904 grams of Brij 30 non-ionic surfactant were weighed out and then added to the cell. 1.2 grams each of water and acrylamide were then pre-mixed to the proper proportions and added as a solution to the cell. Thus, a solution was employed which was comprised of 50/50 acrylamide water, at a water/surfactant mole ratio of 5.0, and an acrylamide/surfactant ratio of 1.25. This recipe gives a total dispersed phase volume fraction of 0.16.
The cell was then sealed and a valve opened, admitting a mixture of ethane/propane gas from a Varian syringe pump which was used to maintain the required pressure. The ethane/propane blends were mixed by weight in a 400 cc aluminum pressure vessel and then transferred to a Varian syringe pump. The temperature of the system was raised to 60 and a hand-operated syringe pump was used to inject a 2% solution in of AIBN initiator (azo-bis(isobutyrnitrile). The polymerization was conducted in about five hours.
More specifically, the experiments were conducted (see FIG. 11) at a pressure of about 5,550 psi and an initiator level of about 1.4 mg. In one experiment involving near-supercritical temperature conditions (64.5~ ethane-35.6% propane), polyacrylamide at a weight-average molecular weight of about 265,000 was produced. In another experiment involving supercritical temperature conditions (51.1% ethane, 48.9% propane), polyacrylamide having a weight-average molecular weight of 575,000 was produced.
Therefore, by employing the process of the present invention, high molecular-weight polyacrylamides can be produced, and unexpectedly, extremely high molecular weight materials can be formed by the process of this invention at temperatures which exceed the supercritical temperatures of the ethane-propane mixture.
1 33~3 1 ~
-REFERENCES
1. Odian, G., Principles of Polymerization, John Wiley & Sons, N.Y., 1981.
2. Candau, F., Y.S. Leong, J. Polym. Sci. - Polym.
Chem. Ed. 1985, 23 193.
One of the independent variables is the choice of initiator, and consequently, the polymerization temperature. Initiation in a true inverse emulsion or microemulsion polymerization occurs in the continuous phase, usually due to degradation of an oil-soluble -1 3~33 1 6 compound. The rate at which these compounds produce radicals is temperature-dependent. A variety of free-radical initiators are available thus allowing reaction to proceed at a reasonable rate at temperatures from 50 to 120C. However, trace oxygen will prompt thermal initiation at higher temperatures, which, in the interests of good control over the reaction, is undesirable. Application of radiation will permit a fast reaction at lower temperatures, and can even preclude the need for a chemical initiator, but again could lead to initiation at sites other than in the continuous phase. Therefore, the initiator azo bisisobutyrnitrile (AIBN), which is usually used at temperatures between 50 and 70C,l was chosen. In order to obtain the process advantages inherent in using a supercritical continuous phase while minimizing the required operating pressure, it would be desirable to run the polymerization reaction as close to the critical temperature of the fluid as possible.
Fortunately, rather than searching for a fluid with a critical temperature in the 50-70C range, a mixture of ethane and propane can be used. The phase behavior of this microemulsion system in ethane/propane mixtures appears to depend on the fluid density, and not on the fluid structure. If the polymerization is to be run in the temperature range of 50-70C, while remaining approximately 5C above the continuous phase Tc, the alkane mixture should be 50 to 80 weight percent ethane (see FIG. 6).
Setting the reaction temperature will also determine the maximum dispersed phase volume fraction which will permit a transparent, stable microemulsion.
As shown in FIG. 12, the ceiling temperature for stability of this microemulsion system decreases sharply as the dispersed phase volume fraction is increased. The minimum dispersed phase volume fraction t 3333 1 6 is set by the selection of the maximum operating pressure allowed for a given reaction vessel. Results in FIG. 7 show the surprising result that the clearing pressure for this microemulsion system increases rapidly below approximately 10%. Thus, once the maximum and minimum volume fractions are set, the actual volume fraction for the reaction can be chosen, and thus the operating pressure range (between the clearing pressure and the safe maximum for the reaction vessel).
The selection of acrylamide and water concentrations are also regulated by the phase behavior. Because acrylamide is a cosurfactant in the non-ionic surfactant-water-ethane/propane system, as the acrylamide is consumed during the polymerization, a point may be reached where the microemulsion will become turbid and begin to phase-separate. This situation can be postponed by setting the acrylamide ratio to 1.25, which is at the maximum of the AM-water curve (FIG. 11).
Example 1 Experiments were conducted in which an acrylamide monomer was polymerized according to the process of the present invention, under the same reaction conditions, except at different ethane to propane ratios. This resulted in one experiment being conducted above the supercritical temperature of ethane-propane mixture and the other experiment being conducted at near the supercritical temperature of the ethane-propane mixture. Clearly, both reactions exceeded the cloud point density of the ethane-propane low-polarity fluid mixture.
The experimental procedure for each of these processes is as follows:
The processes were all run in a 47cc high pressure view cell at 60C. 3.622 grams of Brij 52 and 0.904 grams of Brij 30 non-ionic surfactant were weighed out and then added to the cell. 1.2 grams each of water and acrylamide were then pre-mixed to the proper proportions and added as a solution to the cell. Thus, a solution was employed which was comprised of 50/50 acrylamide water, at a water/surfactant mole ratio of 5.0, and an acrylamide/surfactant ratio of 1.25. This recipe gives a total dispersed phase volume fraction of 0.16.
The cell was then sealed and a valve opened, admitting a mixture of ethane/propane gas from a Varian syringe pump which was used to maintain the required pressure. The ethane/propane blends were mixed by weight in a 400 cc aluminum pressure vessel and then transferred to a Varian syringe pump. The temperature of the system was raised to 60 and a hand-operated syringe pump was used to inject a 2% solution in of AIBN initiator (azo-bis(isobutyrnitrile). The polymerization was conducted in about five hours.
More specifically, the experiments were conducted (see FIG. 11) at a pressure of about 5,550 psi and an initiator level of about 1.4 mg. In one experiment involving near-supercritical temperature conditions (64.5~ ethane-35.6% propane), polyacrylamide at a weight-average molecular weight of about 265,000 was produced. In another experiment involving supercritical temperature conditions (51.1% ethane, 48.9% propane), polyacrylamide having a weight-average molecular weight of 575,000 was produced.
Therefore, by employing the process of the present invention, high molecular-weight polyacrylamides can be produced, and unexpectedly, extremely high molecular weight materials can be formed by the process of this invention at temperatures which exceed the supercritical temperatures of the ethane-propane mixture.
1 33~3 1 ~
-REFERENCES
1. Odian, G., Principles of Polymerization, John Wiley & Sons, N.Y., 1981.
2. Candau, F., Y.S. Leong, J. Polym. Sci. - Polym.
Chem. Ed. 1985, 23 193.
3. Candau, F., Z. Zekhnini, J.P. Durand, J. Coll.
Int. Sci. 1986, 114, 398.
Int. Sci. 1986, 114, 398.
4. Leong, Y.S., S.J. Candau, F. Candau, in Surfactants in Solution, Vol. III, Eds. K.L.
Mittal, B. Lindman, Plenum Press, N.Y., 1983, p.
Mittal, B. Lindman, Plenum Press, N.Y., 1983, p.
5. Graillat, C., C. Pichot, A. Guyot, M.S. El Aasser, J. Polym. Sci. - Polym. Chem. Ed. 1986, 24, 427.
6. Vanderhoff, J.W., E.B. Bradford, M.L. Tarkowski, J.B. Schaffer, R.M. Wiley, Ad. Chem. Ser. 1962, 34, 32.
7. Baade, V., K.H. Reichert, Eur. Polym. J., 1984, 20, 505.
8. Vanderhoff, J.W., F.V. Distefano, M.S. El Aasser, R. O'Leary, O.M. Schaffer, D.G. Visioli. J.
Dispers. Sci. Tech., 1984, 5, 323.
Dispers. Sci. Tech., 1984, 5, 323.
9. McHugh, M.A., V.J. Krukonis. Supercritical Fluid Extraction, Butterworths, Boston, 1986.
10. Fulton, J.L., R.D. Smith. J. Phys. Chem., 1988, 92, 2903.
11. Kotlarchyk, M., S. Chen, J.S. Huang, M.W. Kim.
Phys. Rev. A 1984, 29, 2054.
Phys. Rev. A 1984, 29, 2054.
12. Windholz, M., S. Budavari, eds. The Merck Index, Tenth Ed., Merck and Co., Rahway, N.J., 1983.
13. Parrish, W.R., A.G. Pollin, T.W. Schmidt. Proc.
Sixty-First Ann. Conv., Gas Proc. Assoc., 1982, 164.
Sixty-First Ann. Conv., Gas Proc. Assoc., 1982, 164.
14. Leong, Y.S., F. Candau, G. Pouyet, S.J. Candau.
J. Coll. Int. Sci., 1984, 101, 167.
J. Coll. Int. Sci., 1984, 101, 167.
15. Shinoda, K. S. Friberg. Emulsions and Solubilization, John Wiley and Sons, N.Y., 1986.
133331~
-16. Griffin, W.C. J. Soc. Cosmet. Chem., 1949, 1, 311.
133331~
-16. Griffin, W.C. J. Soc. Cosmet. Chem., 1949, 1, 311.
17. Boyd, J.G. Parkinson, P. Sherman. J. Coll. Int.
Sci. 1972, 41, 359.
Sci. 1972, 41, 359.
18. Reynolds, W.C. Thermodynamic Properties in SI, Dept. of Mech. Eng., Stanford Univ., Stanford, CA
1979.
1979.
19. Matschke, D.E., G. Thodos. J. Chem. Eng. Data 1962, 7, 232 20. Schauber, C., & G. Riess. Polym. Mat. Sci. Eng.
1987, 57, 945.
1987, 57, 945.
21. Haque, E., & S. Qutubiddin. Polym. Mat. Sci. Eng.
1987, 57, 944.
1987, 57, 944.
22. Becher, P., in Surfactants in Solution, Vol. III, K.L. Mittal, B. Lindman, eds., Plenum Press, N.Y.
1983, p. 1925.
1983, p. 1925.
23. Wormuth, K.R. & E.W. Kaler, submitted to J. Phys.
Chem.
Chem.
24. Wormuth, K.R. & E.W. Kaler, J. Phys. Chem., 1987, 91, 611.
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E~ W 1~ ~ 11 0 ~1 3 ~0 OD ~ ~r N _I N O ~ 0 O Z 'P ~r ~r ~ ~r ~ ~ S a) ~D
o ~ ~ ~ a~ r ~ o o ~ o o o o o o o O
O O~ _ _I N 1 o _I N ~ ~r Ir) ~ l N ~ ~r u~ D _I N ~) ~r 11') ~ Z
1~333~6 Having illustrated and described the principles of our invention in a preferred embodiment thereof, it should be readily apparent to those skilled in the art that the invention can be modified in arrangement and detail without departing from such principles. We claim all modifications coming within the spirit and scope of the accompanying claims.
Claims (36)
1. A process for polymerizing a monomer which comprises forming a microemulsion system comprising a first phase including a low-polarity fluid material which is a gas under standard temperature and pressure and has a cloud-point density, and a second phase including a polar fluid, a monomer substantially soluble in said polar fluid, and a microemulsion promoter for facilitating the formation of micelles including said monomer in said system;
maintaining the system at a pressure and temperature such that the density of the low-polarity fluid exceeds the cloud-point density thereof;
forming micelles including said monomer in said microemulsion system;
introducing a polymerization initiator into the micelles in said microemulsion system; and polymerizing said monomer in said micelles to produce a polymeric material.
maintaining the system at a pressure and temperature such that the density of the low-polarity fluid exceeds the cloud-point density thereof;
forming micelles including said monomer in said microemulsion system;
introducing a polymerization initiator into the micelles in said microemulsion system; and polymerizing said monomer in said micelles to produce a polymeric material.
2. The process of claim 1, wherein said first phase comprises a substantially continuous phase, said second phase comprises a substantially discontinuous phase, and said microemulsion comprises a substantially stable inverse emulsion.
3. The process of claim 1, wherein said poly-merization is conducted at a temperature at least equal to the supercritical temperature of said fluid material.
4. The process of claim 2, wherein said monomer comprises a water-soluble monomer.
5. The process of claim 4, wherein said water-soluble monomer comprises at least one of acrylamide, methacrylamide, acrylic acid, methacrylic acid, an acrylic acid salt, vinyl pyrolidone, and vinyl acetate.
6. The process of claim 1, wherein said microe-mulsion promoter comprises a surfactant which is substan-tially soluble in said second phase.
7. The process of claim 1, wherein the molar ratio of said microemulsion promoter to said polar fluid is at least about 5, and said microemulsion promoter substan-tially solubilizes said polar fluid at pressures up to 500 bar.
8. The process of claim 1, wherein said microe-mulsion promoter comprises at least one of a non-ionic surfactant and an anionic surfactant.
9. The process of claim 8, wherein said sur-factant has an HLB of from about 6 up to 8.
10. The process of claim 1, wherein said monomer acts as a microemulsion co-promoter in said second phase.
11. The process of claim 1, wherein said fluid material is at least one lower alkane.
12. The process of claim 1, wherein said lower alkane is at least one of ethane, propane and butane.
13. The process of claim 2, wherein said poly-merization initiator is capable of passing through said continuous phase and into said discontinuous phase for polymerizing said monomer in said micelles.
14. The process of claim 1, wherein said polymerization initiator is activated by at least one of thermal and radiation means.
15. The process of claim 1, wherein said polymerization initiator comprises any one of azo, peroxide, and disulfide initiator compounds.
16. The process of claim 1, wherein the pressure required to form said microemulsion system is reduced as the amount of said second phase in said microemulsion system is increased.
17. The process of claim 3, wherein the weight average molecular weight of said polymeric material polymerized at a temperature above the supercritical temperature of said fluid material is at least 25%
greater than the weight average molecular weight of the polymeric material produced under substantially the same reaction conditions except that the polymerization is conducted at a temperature below the supercritical temperature of said fluid material.
greater than the weight average molecular weight of the polymeric material produced under substantially the same reaction conditions except that the polymerization is conducted at a temperature below the supercritical temperature of said fluid material.
18. A microemulsion system comprising a first phase including a low-polarity fluid material which is a gas under standard temperature and pressure and has a cloud-point density, a second phase including a polar fluid, a monomer substantially soluble in said polar fluid, and a microemulsion promoter for facilitating the formation of micelles including said monomer in said system; and micelles including said monomer in said system, the system being maintained at a pressure and temperature such the density of the low-polarity fluid exceeds the cloud-point density thereof.
19. The microemulsion system of claim 18, wherein said first phase comprises a substantially continu-ous phase, said second phase comprises a substantially discontinuous phase, and said microemulsion system com-prises a substantially stable inverse emulsion.
20. The microemulsion system of claim 18, wherein said monomer comprises at least one of acrylamide, methacrylamide, acrylic acid, methacrylic acid, and acrylic acid salt, vinyl pyrolidone, and vinyl acetate.
21. The microemulsion system of claim 18, wherein said microemulsion promoter comprises a surfactant which is substantially soluble in said second phase.
22. The microemulsion system of claim 18, wherein the molar ratio of said microemulsion promoter to said polar fluid is at least about 5, and said microemul-sion promoter substantially solubilizes said polar fluid at pressures up to 500 bar.
23. The microemulsion system of claim 18, wherein said microemulsion promoter comprises at least one of a non-ionic surfactant and an anionic surfactant.
24. The microemulsion system of claim 23, wherein said surfactant has an HLB of from about 5 up to 10.
25. The microemulsion system of claim 18, wherein said monomer acts as a microemulsion co-promoter in said second phase.
26. A process for polymerizing a water-soluble monomer which comprises forming a substantially stable inverse microemulsion system comprising a first substan-tially continuous phase including a fluid material which is either one of a gas under ambient conditions and a liqui-fied gas, and a substantially discontinuous second phase including water, a water-soluble monomer and a surfactant which is substantially soluble in said second phase for facilitating the formation of micelles including said monomer in said system;
forming micelles including said monomer in said system;
introducing a polymerization initiator capable of passing through said continuous phase and into said micel-les of said discontinuous phase; and polymerizing said monomer in said micelles to produce a polymeric material.
forming micelles including said monomer in said system;
introducing a polymerization initiator capable of passing through said continuous phase and into said micel-les of said discontinuous phase; and polymerizing said monomer in said micelles to produce a polymeric material.
27. The process of claim 26, wherein said polymerization is conducted at a temperature at least equal to the supercritical temperature of said fluid material.
28. The process of claim 26, wherein said water-soluble monomer comprises at least one of acrylamide, methacrylamide, acrylic acid, methacrylic acid, an acrylic acid salt, vinyl pyrolidone, and vinyl acetate.
29. The process of claim 26, wherein the molar ratio of said surfactant to said water is at least about 5, and said surfactant substantially solubilizes said water at pressures up to 500 bar.
30. The process of claim 26, wherein said surfactant comprises at least one of a non-ionic surfactant and an ionic surfactant.
31. The process of claim 26, wherein said surfactant has an HLB of from about 5 up to 10.
32. The process of claim 26, wherein said monomer acts as a co-surfactant in said second phase.
33. The process of claim 26, wherein said fluid material is at least one lower alkane.
34. The process of claim 26, wherein said polymerization initiator is activated by at least one of thermal and radiation means.
35. The process of claim 26, wherein the pressure required to form said microemulsion system is reduced as the amount of said second phase in said microemulsion system is increased.
36. The process of claim 26, wherein the weight average molecular weight of said polymeric material polymerized at a temperature above the supercritical temperature of said fluid material is at least 25%
greater than the weight average molecular weight of the polymeric material produced under substantially the same reaction conditions except that the polymerization is conducted at a temperature below the supercritical temperature of said fluid material.
greater than the weight average molecular weight of the polymeric material produced under substantially the same reaction conditions except that the polymerization is conducted at a temperature below the supercritical temperature of said fluid material.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/125,842 | 1987-11-24 | ||
| US12584287A | 1987-11-27 | 1987-11-27 | |
| US15225688A | 1988-02-04 | 1988-02-04 | |
| US07/152,256 | 1988-02-04 |
Publications (1)
| Publication Number | Publication Date |
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| CA1333316C true CA1333316C (en) | 1994-11-29 |
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ID=26824009
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| CA000584080A Expired - Fee Related CA1333316C (en) | 1987-11-24 | 1988-11-24 | Processes for microemulsion polymerization employing novel microemulsion systems |
| CA000584081A Expired - Fee Related CA1337235C (en) | 1987-11-24 | 1988-11-24 | Chemical reactions in reverse micelle systems |
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| CA000583781A Expired - Lifetime CA1337750C (en) | 1987-11-24 | 1988-11-22 | Supercritical fluid reverse micelle separation |
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|---|---|---|---|
| CA000584081A Expired - Fee Related CA1337235C (en) | 1987-11-24 | 1988-11-24 | Chemical reactions in reverse micelle systems |
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| EP (3) | EP0343233B1 (en) |
| JP (1) | JPH03503180A (en) |
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| CA (3) | CA1337750C (en) |
| DE (2) | DE3887681T2 (en) |
| WO (3) | WO1989004858A1 (en) |
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1988
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- 1988-11-22 CA CA000583781A patent/CA1337750C/en not_active Expired - Lifetime
- 1988-11-22 US US07/274,558 patent/US5238671A/en not_active Expired - Lifetime
- 1988-11-22 EP EP89900727A patent/EP0343233B1/en not_active Expired - Lifetime
- 1988-11-22 DE DE89900727T patent/DE3887681T2/en not_active Expired - Lifetime
- 1988-11-23 DE DE3856403T patent/DE3856403T2/en not_active Expired - Lifetime
- 1988-11-23 WO PCT/US1988/004226 patent/WO1989004844A1/en not_active Application Discontinuation
- 1988-11-23 EP EP89903542A patent/EP0387307B1/en not_active Expired - Lifetime
- 1988-11-23 AT AT89903542T patent/ATE191739T1/en not_active IP Right Cessation
- 1988-11-23 WO PCT/US1988/004230 patent/WO1989005336A1/en active IP Right Grant
- 1988-11-23 JP JP1501093A patent/JPH03503180A/en active Pending
- 1988-11-23 EP EP19890901167 patent/EP0395714A4/en not_active Withdrawn
- 1988-11-24 CA CA000584080A patent/CA1333316C/en not_active Expired - Fee Related
- 1988-11-24 CA CA000584081A patent/CA1337235C/en not_active Expired - Fee Related
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1989
- 1989-06-06 AT AT89900727T patent/ATE101186T1/en not_active IP Right Cessation
Also Published As
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| WO1989005336A1 (en) | 1989-06-15 |
| EP0343233B1 (en) | 1994-02-02 |
| DE3887681D1 (en) | 1994-03-17 |
| EP0343233A4 (en) | 1990-01-11 |
| DE3856403T2 (en) | 2000-10-26 |
| CA1337235C (en) | 1995-10-10 |
| ATE101186T1 (en) | 1994-02-15 |
| EP0387307A4 (en) | 1991-01-02 |
| US5238671A (en) | 1993-08-24 |
| EP0343233A1 (en) | 1989-11-29 |
| ATE191739T1 (en) | 2000-04-15 |
| DE3856403D1 (en) | 2000-05-18 |
| WO1989004844A1 (en) | 1989-06-01 |
| EP0395714A1 (en) | 1990-11-07 |
| EP0387307B1 (en) | 2000-04-12 |
| DE3887681T2 (en) | 1994-05-11 |
| EP0387307A1 (en) | 1990-09-19 |
| CA1337750C (en) | 1995-12-19 |
| JPH03503180A (en) | 1991-07-18 |
| EP0395714A4 (en) | 1991-01-09 |
| WO1989004858A1 (en) | 1989-06-01 |
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