DE3107542A1 - Forming blood contacting polymer surface of biomedical device - Google Patents

Abstract

Process comprises (a) thoroughly dispersing no more than 5 vol. % of a polymer additive (I) throughout at least 95 vol.% of a base polymer (II), (I) and (II) being in fluid form and (b) solidifying the polymer mixt. to form the surface. (I) comprises (i) a first homopolymer chain component chemically bonded to (ii) a second homopolymer chain component of a different type. The additive has a lower surface free energy characterised by Zisman's critical surface tension (gamma.c) than the polymer (II). The polymer mixt. has a gamma.c value of 10-35 dyne/cm. Pref. component (i) has a gamma.c value of below 30 dyne/cm. and tends to exudate whereas (ii) lowers this tendency. (I) lowers the gamma.c value of (II) to render it blood compatible. Biomedical devices include auxiliary ventricles, intra-aortic balloons and blood pumps.

Description

Polymer surfaces for contact with blood

standing surfaces of a biomedical device and methods for their Manufacturing Description A widely accepted hypothesis on compatibility with blood means that this is maximized within a narrow range at surface free energies, creating a beneficial interaction with plasma protein is caused.

A common measurement of the surface free energies is carried out by the critical surface energy (yc) according to Zisman. The optimal value became empirical determined and lies in the range of the values for Yc of about 20 to 30 dynes / cm (cf. e.g., R.A.Baeir, Ann. N.Y.

Acad. Sci. 17, p. 283 (1977)).

Above all polymers (e.g. polyurethanes) which have the desired physical Properties for blood-contacting biomedical surfaces Devices often do not fall into this critical surface tension range.

It is known that polysiloxanes have a particularly low value for possess the critical surface tension and it has therefore been proposed to use them in polyurethanes to improve the surface properties of such materials to improve.

However, it is also known that polysiloxanes themselves have a tendency to to be precipitated from the polyurethane base polymer, as in U.S. Patent 3,243 475 was described.

Polysiloxane-polyurethane block copolymers were disclosed in U.S. Patent 3,562,352 Suggested for use to measure the surface properties of blood in contact to modify stationary surfaces of facilities of biomedical devices. The technique described for this use involves the manufacture of the whole blood contact device made of such block copolymers or the Coating these devices with the copolymers. The block copolymers have themselves poor structural characteristics due to the high content of polysiloxane. on the other hand the coated materials are particularly expensive in the Shaping, because they cannot be processed by thermoplastic processes, such as by an injection molding process or by extrusion. The production of pipes, Catheters and other devices made of such materials which can be exposed to contact with blood is particularly expensive due to the need to apply the techniques of Solution manufacturing.

Some experimental work has been published on the problem of blending block copolymers of polydimethylsiloxane with homopolymers of higher critical surface tension. These materials are known to be films with high siloxane surface concentrations. It will do so on the following Publications referenced: D.G.Legrand and R.L. Gaines, Jr., Polym.Prepr. 11 Page 442 (1970); D.W.Dwight et al., Polym.Prepr. 20, (1), - page 702 (1979); J.J. O'Malley, Polym.Prepr. 18, (1977), However, all of these literatures describe the polymer blends from a scientific point of view without any indication that these materials bring an advance in application in a biomedical field of application.

An object of the invention is to use a new form of polymer create lower surface free energy for use as a surface a medical device in contact with blood. The new polymer form should be inexpensive and quickly processable and have excellent technical properties exhibit. Other objects and features of the invention will be apparent from the following Description of the preferred embodiments clearly.

In accordance with the aforementioned objects of the invention a new technique was created for training those subject to contact with blood Surface of a biomedical device or part thereof. In one embodiment becomes a minor part of a polymer additive in the base polymer dispersed, while both are in the liquid state, thereby forming a polymer blend will. The polymer additive comprises at least two different honey polymer chains, preferably in the form of a graft or block copolymer; One of the chains owns a low surface free energy (e.g. a polysiloxane), while the other chain is characterized by the ability to tilt this material to reduce the excretion from the base polymer. The base polymer is preferably made and the second component of the polymer additive made of the same material (e.g. made of polyurethane). The polymer addition serves to reduce the critical surface tension of the base polymer to make it compatible with blood.

A main feature of the invention is to provide a technique for Reducing the surface free energy of a well structured polymer in order to a surface formed from this material is of an incompatible state transferred to a compatible state. The term "base polymer" used here refers to the polymer whose surface properties are modified in this way are. Typical base polymers, the surfaces of which by means of the technique according to the invention can be improved are, for example, polyurethanes, polysulfones, polycarbonates, Polyester, polyethylene, polypropylene, polystyrene, poly (acrylonitrile-butadiene-styrene), Polybutadiene, polyisoprene, styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene -Block copoly'-mers, poly-4-methylpentene, polyisobutylene, polymethyl methacrylate, Polyvinyl acetate, polyacrylonitrile, polyvinyl chloride, polyethylene terephthalate, cellulose and their esters and derivatives.

The base polymer is of a type that becomes a self-supporting structural Body or self-supporting film can be molded or as a coating can be applied to a self-supporting body. The ultimate use The end product is its use as the surface of a biomedical device or a part.

Another property of the base polymer is that its critical surface tension (µ) is above that which is desirable for a surface in contact with blood and is also higher than the critical one Surface tension of the polymer additive described below and which one reduces the c value of the base polymer. Measurements of c are used in this application carried out by the direct method using a measuring device for Measurement of the contact angle according to Kernco or Rame-Hart and a sequence of seven Solvents in accordance with the Zisman method as described is from A.W. Adamson, Physical Chemistry for Surfaces, pages 339 to 357, 351 (3. Output). The measurements were carried out at room temperature using increasing angle of solutions cast into films that have been annealed at 60 ° C for 4 hours became. The main contact angles were combined to form a Zisman curve below -Use of a computer program for linear regression.

According to the invention there is provided a base polymer of the type previously described with a polymer addition, as described below, to reduce its surface free energy mixed.

This polymer additive with a significantly lower value for than as the base polymer, is thoroughly dispersed in the base polymer while it is is in liquid form to form a liquid polymer mixture. Then the polymer mixture solidifies and becomes a surface in contact with blood a biomedical device or a part thereof. A suitable broad range of surface free energy of the polymer mixture is from 10 to 35 dynes / cm, with a range of 20 to 30 dynes / cm being preferred. Particularly preferred is the range from 20 to 25 dynes / cm.

The polymer additive comprises at least two different homopolymer chain components with different functional properties. A homopolymer chain, which hereinafter as first component "has a relatively low value for Ycs which is lower than the corresponding value of the Base polymer and the second component -and causes the decrease in value for v, c of the polymer mixture described below. Such a material typically has a tendency to segregate from the base polymer in the blend.

In order to prevent excretion, at least a second homopolymer chain, hereinafter referred to as the "second component" to the first component chemically bound in the polymer additive to reduce the tendency to precipitate. The second component can be selected from the group of "hard block" polymer segments be used in the manufacture of thermoplastic block copolymers (see A.Noshay and J.E. McGrath, Block Copolymers Overview and Critical Survey, flcademic Press 1977 ». The hard blocks made by a crystalline melting point greater than 37 "C and / or a glass transition temperature also greater than about 37 "C. The second component has a higher surface free energy than the first component. For reasons the compatibility, the second component is preferably made of a polymer of the of the same type as the base copolymer.

It was found that the homopolymer component of the additive with the lowest value for c determines the c value of the total polymer addition. Has thus, for example, the first component has a c value of 25 and the second component a value of 35, the total yc value of the associated addition is approximately 25; Suitable Homopolymers for the first component are those with a c value in the desired one Range to decrease the value of the base polymer to the desired value for the blood tolerance. So it is preferred that such first Component has a yc value of less than 30 dynes / cm. A particularly effective one Homopolymer for this purpose is a polydimethylsiloxane with a y value in the Size of 22 dyn / cm. The techniques for forming siloxane copolymers for use in the invention are known, for example from W. Noll, Chemistry and Technology of Silicones (Academic Press, 1968). Suitable homopolymers for the first component are other polydialkylsiloxanes, polyfluoroalkylalkylsiloxanes, polyalkylene oxides, Polyolefins, polydienes, and polyfluorocarbons.

If the polymer mixture according to the invention by mixing a pre-formed Polymer additive of the type mentioned above is formed with a base polymer, such a polymer additive is expediently made from block copolymers or alternating first and second components, which are interconnected by chemical Links are linked' formed according to known techniques. For example, can such block copolymers in accordance with the aforementioned publications formed by Noshay and McGrath. A suitable number of recurring Units of each- homopolymer of the first component is that which leads to Maintaining the value of the homopolymer is sufficient as by maintaining it about the same glass transition temperature as that of the pure homopolymer will. Typically this number is on the order of 5 to 10 units or above. Similarly, there should be a sufficient number of recurring Units of the second component may be present in a segment, so that the polymer additive is solid at room temperature.

The production of block copolymers (or multipolymers) can according to different procedures are carried out, which differ from each other in extent, in which the structure of the product obtained can be defined.

One method involves coupling two (or more) preforms Blocks made in two separate reactions before the coupling reaction have been. This procedure results in a very well defined structure, though the linking reaction excludes the implementation of blocks with itself and only enables the linking of different blocks with one another.

A structure that is only slightly worse defined results when two preformed blocks have the ability (via a linkage reaction) with themselves even how to react with different blocks.

An even more poorly defined structure results when a single (or more) preformed block with a second block, which during the linking reaction originated, is connected. In this case the starting length is the preformed one Blocks known (due to the separate reaction used in its manufacture was), but the sequence distribution of the copolymer is not exactly known because both linkage and chain growth are possible in the second reaction which creates the second block. Appropriate method of training the one or other types of these copolymers for use in the invention are from US Pat known from the aforementioned publication by Noshay and McGrath.

A single special mixture according to the invention comprises a block or graft copolymer of a polydialkylsiloxane, in particular a polydimethylsiloxane, as the first component and a polyurethane as the second component. The following The term "polyurethane" used includes polyurethane ureas, polyether urethanes, Polyester urethanes and other known polyurethanes, as described for example are in U.S. Patent 3,562,352 (column 2, line 66 through column 3, line 37). This Copolymer can be made with any base polymer with the desired physical Properties are mixed. According to the invention, it is particularly effective for mixing the same way to use basic poiyme.r as the second component, which means improved compatibility is achieved.

If desired, three or more types of polymer chains can be used can be used in a sequence as long as at least one species is a low one Has value for u, c. An excellent tar polymer additive comprises a block copolymer segment from the first and second components. The second component is with a segment connected, which is specifically made of either polyethylene oxide or polyethylene oxide-copolypropylene oxide is produced and is hereinafter referred to as the "hydrophilic component". In in this case the second component is a hard block with a crystalline melting point above 37 "C or a glass transition temperature above 37" C. In one Terpolymer of this type connects the second component to the first component and the hydrophilic component. In an excellent terpolymer is the first component a polydialkylsiloxane, the second component is a compound from the broad Group comprising polyurethane and polyurea urethane and the hydrophilic component is either polyethylene oxide or polyethylene oxide-copolypropylene oxide. This terpolymer provides an unexpectedly superior improvement in blood compatibility for a base polymer with the desired structural properties, such as a hard polymer of the same Kind-as the second component; Other forms of linked first and second Homopolymers are of the graft copolymer type. Either the first or that second copolymers can serve as a substrate on which the pendant chains of the other homopolymer are grafted on. The way of formation of Graft copolymers are known to those skilled in the art of polymer chemistry. It will continue to be on pages 13-23 of the aforementioned publication referenced by Noshay and McGrath. The third Mechanism in table 2-1- illustrates a framework structure suitable for grafting a polydimethylsiloxane with hydroxyalkyl end groups (e.g. by using a urethane linkage of a diisocyanate).

The ratio of the first and second components in the polymer additive can vary to a remarkable extent as long as a sufficient amount of the first component is present in order to reduce the c value, and a sufficient one Amount of second homopolymer is present to prevent precipitation of the polymer additive to prevent. It is preferred that the polymer additive be at least about 20% by volume the first component comprises. A suitable ratio is in the range of 20 up to 80% by volume of the component of the first type and about 20 to 80% by volume of the component of the second type of polymer.

The total amount of polymer added to reduce the c value of the base polymer to the desired value for the polymer mixture is required, is very low. For example, it has been found to be less than 5% by volume and preferably less than 1 to 2 volume% of the total polymer additive for silicone than the first Component fulfills this function, albeit the first component in a typical manner contains about half or less of the polymer additive. A suitable relationship of polymer addition to base polymer is in the range from 0.00002 to 2 volume - *% Polymer addition based on the total polymer mixture.

Experimental results have shown that even with original Mixing the polymer additive in bulk in the base polymer, this to the surface migrates and forms an extremely thin (monomolecular) film, which provides the desired surface properties. There should be enough polymer addition exist to provide this uniform layer. The presence an adequate amount of polymer addition is achieved by a dramatic drop in c The value of the polymer mixture is shown approximately on the value of the first component.

While the required amount varies from system to system is, so it is generally less than 1% by volume of the first component on the entire polymer mixture.

It is advantageous to add such small amounts of the polymer additive use as large amounts of the first component for physical properties of the polymer mixture can be disadvantageous.

It has been found that the minimum amount of polymer additive required can be approximated by knowing the film thickness of a polymer additive monolayer and the ratio of surface area to mass volume of the manufactured Materials. This approximation is based on the simplifying assumption that before saturation Essentially all of the polymer additive migrates to the surface of the surface. This minimum amount can be calculated simply on the basis of this Knowledge can be calculated in advance.

A number of techniques can be used for blending the polymer additive can be used with the base polymer according to the invention. According to one technique Both the base polymer and the polymer additive are thermoplastic and at melted at elevated temperatures to allow mixing. The following is the polymer solidifies by cooling. If desired, the mass polymer can mer simultaneously processed into the desired final shape. Alternatively for this purpose, the material can be solidified for the subsequent formation of the material to the desired shape by thermoplastic methods such as injection molding and extruding.

Another technique for mixing the polymer additive and base polymer sees the dissolution of both in a solvent and the subsequent evaporation of the solvent, whereby the solid product of the invention is formed. This product can subsequently, if so desired, also by techniques processed in the field of thermoplastics.

A third technique for forming the polymer blend of the present invention is the polymerization in place (polymerize-in place) with a-large excess (e.g. of at least 95 volume-) of the base polymer and a lesser amount (e.g. a maximum of 5 volumes) of a homopolymer additive of the type of the first component, such as it was previously described. For example, one is terminated with hydroxypropyl groups provided polydimethylsiloxane of low molecular weight instead of a low one Amount of polyether glycol used in the synthesis of a typical polyether urethane. Here the reaction product can contain enough silicone / polyurethane block copolymer to provide the desired surface properties. The concentration of the polymer addition is so small that the large excess (for example at least 95% by volume) of the base polymer is not linked to the additional polymer.

The polymer additive of the present invention must be thorough in the base polymer be dispersed. For this purpose it is preferred that the polymer additive be thermoplastic, is soluble in organic solvents and is relatively poorly crosslinked.

For most biomedical applications, the invention Base polymers can be thermoplastic so that they can be quickly if so desired can be processed.

However, there are areas of application in which the polymers in liquid-r Shape - can be processed and subsequently to the shape of the manufactured parts can be solidified, which are not returned to the liquid form can be.

For example, such a base polymer can be thermosetting systems contain which hardened or immediately after the dispersion of the polymer additive to be vulcanized. These systems can be 2-component polyurethane or epoxy resin systems include.

A system preferred according to the invention comprises a mixture of a polymer additive from a polydialkylsiloxane segment, which chemically to a polyurethane segment is bound (for example in a block or graft copolymer) and with a suitable base polymer is mixed, for example of the type of polyurethane as in the copolymer. A particularly effective system comprises a polymer additive, which is a Block copolymer with about 50% by weight of polydimethylsiloxane and 50% by weight of polyurethane (especially polyester urethane) in a base polymer made of polyurethane (especially Contains polyester urethane. A suitable ratio is 99.9% polyester urethane Base polymer and 0.1% block copolymer.

A way of pretreating a base polymer to reduce its Surface free energy is believed to be effective on a base polymer which Includes high energy end groups, particularly for hydrogen bonding or reaction end groups capable of protein. In this case, the base polymer is first fractionated to separate a fraction of lower molecular weight and this can reduce the ability of the remaining base polymer to hydrogen bond be reduced. Appropriate techniques for performing this method are out the literature by Manfred J.R. Cantow, Polymer Fractionation, Academic Press (New York - London 1967) known. These techniques include liquid chromatography, especially gel chromatography.

It has been found that changes in process conditions, which would affect the surface free energy to a significant extent, in Systems that can be minimized by the present invention as a factor the application of a brief heat treatment following surface formation.

For example, in a system with a base polymer made of polyether urethane and a block copolymer of polyether urethane / polyalkylsiloxane, heating for 4 hours to 75 0C to a t c value which approximately corresponds to that of the pure polysiloxane, while it takes a remarkably longer time to complete this task at room temperature perform.

It was also found that the polarity of the environment of the formation affects the # c value of the surface. So provides a surface balanced with air a lower c value than a water-leveled surface Polymer blends are particularly effective when used in contact with blood standing surfaces of a biomedical device or a part thereof.

Such devices include auxiliary ventricles, intra-aortic recipients and different types of blood pumps.

A further exposition of the nature of the present invention is provided by means of of the following specific exemplary embodiments are set out in practice. the The data given serve only as an example and do not restrict The invention.

Example 1 Typical synthesis of a polydimethylsiloxane-polyurethane block copolymer.

In a 500 ml, with a stirrer, a -Dean-Stark separating funnel, a dropping funnel, a drying tube, a thermometer and an inlet for inert gas equipped four-necked flask was a mixture of 50 ml of dimethylformamide and 140 ml of tetrahydrofuran added. The mixture was heated to reflux and about 40% ml of tetrahydrofuran were distilled off.

The reaction mixture was cooled and 12.513 g (0.05 mol) of methylene bis (4-phenyl) isocyanate (MDI) were added. A clear solution was obtained. Above the dropping funnel 15,000 9 (0.015 mole) polydi-methylsiloxane terminated with 3-hydroxypropyl groups (Molar weight ~ 1000) added drop by drop. The reaction mixture was 1 hour heated to 105 to 100 ° C, then were added dropwise 3.15 9 (0.035 Mol) 1,4-butanediol was added within 45 minutes. The polymerization was Carried out for 15 minutes or more, followed by cooling and pouring precipitated in water in a mixer.

The light yellow polymer was washed with water and finally washed with ethanol and dried in a vacuum drying cabinet at 50 ° C. It Approx. 30 to 31 g of polymer (98 to 100%) were obtained. The value [q] in tetrahydrofuran at 25 "C was 0.19.

Example 2 By replacing part of the polydimethylsiloxane with Hydroxypropyl end groups through polyethylene glycol became a polydimethylsiloxane / polyethylene oxide / polyurethane terpolymer manufactured.

Example 3 By replacing the DMF solvent with dimethylacetamide and replacement of the butanediol by ethylenediamine in Example 2 was polydimethyl sil oxane / polyethylene oxide / polyurea urethane terpolymer produced.

EXAMPLE 4 This example illustrates the manufacture the solution.

A solution was prepared which contained about 10% by weight mixture in a solvent system of 90% tetrahydrofuran (volume / volume) and 10% dimethylformamide contained. The mixture consisted of 99.9% by weight of purified polyester urethane and 0.1% by weight silicone / polyurethane block copolymer. The block copolymer consisted of about 50% by weight of polydimethylsiloxane and 50% by weight of polyurethane from diphenylmethane diisocyanate and butanediol.

The solution was made of corrosion-resistant tapered mandrels Steel applied by multiple dips. The solvent evaporated and the film was pulled from the mandrel. The "balloon" obtained was pre-drilled onto a Catheter pulled up and was suitable as a heart locking device (cardiac arrest device) when inserted into the descending aorta and was inflated with CO2 and sank again with counterpulsation (counterpulsation) to the heart The y value of the balloon film was 20 to 22 dynes / cm.

EXAMPLE 1 5 Small test tubes were attached to their inner surfaces with two different polymer solutions (in THF) in a concentration of 10 % By weight coated. One solution contained polyether urethane in the solvent. The second solution contained 90% by weight solvent, 9.9% by weight polyether urethane and 0.1% by weight copolymer additive. The copolymer consisted of about 50% polydimethylsiloxane and 50% polyethylene oxide / copolypropylene oxide available from Petrarch Systems is sold under the trade name PS 072.

After evaporation of the solvent and about 16 hours of equilibration in distilled water, fresh pure blood was poured into the three tubes of each type brought in.

The tubes coated with the unmodified polyether urethane showed, on average, total blood clotting within 39 minutes. Those coated with polyether urethane with the addition of the block copolymer additive Tubes showed, on average, that the whole blood coagulated after more than 70 minutes.

The y value of the unmodified polyurethane urethane is around 28 dyn / cm. The c value of the polyether urethane with the addition of the block copolymer additive is about 20 dynXcm; Example 6 This example illustrates thermoplastic manufacture.

A thermoplastic polyurethane was made in a screw extruder at about 204 "C (4000F) with a block copolymer additive of about 50 weight percent polydimethylsiloxane and 50 wt .-% polyether urethane mixed so that the total silicone Kanzentration of the mixture was 0.01% by weight. The mixture was extruded into one for the Suitable tube system for blood transfer. The tube system has a yC value of approx 21 dynes / cm after heating at 60 "C for 6 hours.

Example 7 This example illustrates 2-component vulcanization.

A prepolymer with polyether urethane isocyanate end groups the company 'DuPont (Adipren L-167) was made according to the manufacturer's recommendations for a polyol cure shown using a low stoichiometric Deficiency of butanediol / trimethylolpropane mixture. Still in the liquid state 0.1% by weight of the block copolymer additive according to Example 1 was mixed with the reactants and an amine catalyst mixed.

The resulting mixture was applied to a previously primed titanium connector applied and cured in an oven at 100 ° C.

The coated connector had a Yc value of about 20 dy-n / cm and was brought into contact with blood to form a management to connect to an auxiliary device in the left ventricle, which is used for treatment the low cardiac output is used (low cardiac output syn-drome).

Example 8 A 4 mm tubular prosthesis was formed by Coating of a mandrel made of corrosion-resistant steel with a polymer mixture 99.9% by weight of polyether urethane urea and 0.2% by weight of polydimethylsiloxane / polyurethane block copolymer from 50% polydimethylsiloxane and 50% polyurethane in a solution of dimethylacetamide. After evaporation of the solvent, the tube obtained was removed from the mandrel, Extracted for 16 hours at 60 ° C with distilled water, dried and 4 hours heated at 60 ° C. After sterilization with ethylene oxide, the tube was inserted into the large carotid artery of a goat sewn in.

Using an established technique for using radioactive labeled platelets did not accelerate platelet conversion measured relative to a simulated experiment. A corresponding experiment detected slight changes in platelet conversion in polyvinyl chloride tubes, it is known that polyvinyl chloride is poorly tolerated by blood owns.

Claims (40)

P a t e n t a n s p r ü c h e II jlProcess for forming a with Blood-contacting surface of a biomedical device or parts thereof, characterized in that (a) at most about 5% by volume of a polymer additive be thoroughly dispersed in at least 95% by volume of a base polymer while the polymer additive and the base polymer are in liquid form, and a polymer mixture is formed, the polymer additive being a first HoIr (oleopolymer chain component contains at least one second homopolymer chain component other than the first is chemically bound, and the polymer additive has a value for the critical Surface tension uc which is below the corresponding value for the Base polymer is and the polymer mixture has a value pc between about 10 and 35 dynes / cm and (b) the polymer mixture solidifies and becomes one with blood surface of a medical device or part that is in contact of which is trained. 2. The method according to claim 1, characterized in that the first Component has a critical surface tension c of less than 30 dynes / cm and has a tendency to excrete and the second component has this tendency decreased for excretion. 3. The method according to at least one of claims 1 and 2, characterized characterized in that the first component is a homopolymer from the group olydialkylsiloxanes, polyfluoroalkylalkyl'-siloxanes, Polyalkylene oxides, Polyolefins, polydienes and polyfluorocarbons. 4. The method according to at least one of claims 1 to 3, characterized characterized in that the first component is polydimethylsiloxane. 5. The method according to at least one of claims 1 to 4, characterized characterized in that the first component is a polydialkylsiloxane and the second Component is a polyurethane. 6. The method according to at least one of claims 1 to 4, characterized characterized in that the second component and the base polymer are made of the same Type of homopolymer are formed. 7. The method according to at least one of claims 1 to 6, characterized characterized in that the base polymer for hydrogen bonding or for reaction with Has protein capable end groups and the base polymer is fractionated to remove a lower molecular weight fraction to reduce hydrogen bonding ability of the remaining base polymer prior to the dispersing step 8. Procedure according to at least one of claims 1 to 7, characterized in that the polymer mixture is tempered. 9. The method according to at least one of claims 1 to 8, characterized characterized in that about 0.00002 to 2% by volume of polymer additive based on the total polymer mixture can be added to the base polymer. 1O.Method according to at least one of claims 1 to 9, 'dadurcll It indicates that the polymer additive is at least about 20% by volume of the first component contains. 11-. Method according to at least one of Claims 1 to 10, characterized in that ' characterized in that the polymer additive is about 20 to 80% by volume of the first component and contains about 80 to 20 volume percent of the second component. 12. The method according to at least one of claims 1 to 11, characterized characterized in that the polymer mixture in the form of a film on a biomedical Applied to the device or part of it. 13. The method according to at least one of claims 1 to 12, characterized characterized in that the additive and base polymer are in molten form solidify during dispersion and on cooling. 14. The method according to at least one of claims 1 to 13, characterized characterized in that the polymer mixture is in a solvent during mixing is dissolved and the solvent is removed to solidify the polymer mixture. 15. The method according to at least one of claims 1 to 14, characterized characterized in that the base polymer is a thermosetting liquid polymer, which solidifies on hardening. 16. The method according to at least one of claims 1 to 15, characterized characterized in that the polymer additive is a linear multiblock copolymer with blocks of at least the first and second components. 17. The method according to at least one of claims 1 to 16, characterized characterized in that the polymer additive contains a graft copolymer with a substrate, which is formed from the first component and side chains which are formed from the second Component are formed. 18. The method according to at least one of claims 1 to 16, characterized characterized in that the polymer additive contains a graft copolymer with a substrate, which is formed from the second component and side chains which are formed from the first Component are formed. 19. Process for forming a polymer with low surface free energy, characterized in that (a) about 0.00002 to 2% by volume of a homopolymer additive be reacted with at least 98 volume of a base polymer, with the addition of homopolymer and the base polymer is in liquid form and a liquid polymer blend form with at least 95% by volume of the pure base polymer and at most 5% by volume a copolymer made up of the base polymer and the homopolymer additive, and (b) the polymer blend is solidified, the additional polymer having a value for the critical surface tension Yc which is below the corresponding value of the base polymer and the polymer mixture has a value y between approximately 10 and 35 dynes / cm. 20. The method according to at least one of claims 1 to 19, characterized characterized in that the polymer mixture is in contact with blood Surface of a biomedical device or a part thereof is formed. 21. Biomedical device or part thereof comprising one with blood compatible surface in contact with blood made of a polymer mixture, characterized in that the polymer mixture is at least 95% by volume of a base polymer and at most 5% by volume of a polymer additive containing a first homopolymer chain component, with at least one second homopolymer chain component of others Kind as the first component is chemically linked, contains, and the polymer additive is dispersed in the base polymer and has a value for ec that is below of the corresponding value for the base polymer and the polymer mixture is one Y, c has a value between about 10 and 35 dynicm. 22. Biomedical device according to claim 21, characterized marked-ichnet, that the first component has a value for uc of less than 30 dynes / cm and has a tendency to precipitate and the second component has a tendency to precipitate decreased. 23. Biomedical device according to at least one of claims 21 and 22, characterized in that the first component is a homopolymer of the Group polydialkylsiloxanes, polyfluoroalkylalkylsiloxanes, polyalkylene oxides, polyolefins, Is polydiene and polyfluorocarbons. 24. Biomedical device according to at least one of claims 21 to 23, characterized in that the first component is polydimethylsiloxane. 25. Biomedical device according to at least one of claims 21 to 24, characterized in that the first component is a polydialkylsiloxane and the second component is a polyurethane. 26. Biomedical device according to. at least one of claims 21 to 25, characterized in that it is compatible with blood and in the form of a any device or part thereof that is in contact with blood is present. 27. Biomedical device according to at least one of claims 21 to 26, characterized in that it is compatible with blood and in the form of a layer in contact with blood which forms the surface of the adheres to the device in contact with blood> 'is present. 28. Biomedical device according to at least one of claims 21 to 27, characterized in that part of the polymer additive in the form of a continuous layer on the surface of what is in contact with blood Device is present. 29. Biomedical device according to at least one of claims 21 to 28, characterized in that part of the polymer additive is a linear multiblock copolymer with blocks of at least the first and second components on the surface a device in contact with blood. 30. Biomedical device according to at least one of claims 21 to 29, characterized in that part of the polymer additive is a graft copolymer with a substrate from the first component and side chains from the second component on the surface of a device in contact with blood. 31. Biomedical device according to at least one of claims 21'bis 29, characterized in that part of the polymer additive is a graft copolymer with a substrate from the second component and side chains from the first component on the surface of a device in contact with blood. 32. Method of forming a polymer blend with lower free Surface energy from a base polymer and a polymer additive, wherein the base polymer contains end groups capable of hydrogen bonding or reaction with protein, thereby marked that (a) the base polymer is fractionated to give Reduce the value of Yc of the remaining base polymer with a fraction separate lower molecular weight, (b) at most about 5% by volume of a polymer additive are thoroughly dispersed in at least 95% by volume of a base polymer, wherein the polymer additive and the base polymer are in liquid form, and a polymer mixture is formed, wherein the polymer additive is a first component with a homopolymer chain having at least one second component with homopolymer chain from another Kind, as the first component, is chemically bound and the polymer additive is one Has value for c which is below the corresponding value for the base polymer and the polymer mixture has a value y, c between about 10 and 35 dynes / cm; and (c) solidifying the polymer blend. 33. Polymer mixture compatible with blood, characterized in that that there is at least 95% by volume of a base polymer and at most 5% by volume of a polymer additive containing a polydialkylsiloxane segment which is chemically attached to a polyurethane segment is bound, wherein the polymer additive is dispersed in the base polymer and has a value for y, c which is below the corresponding value for the Base polymer is and the polymer mixture has a value y, c between about 10 and 35 dyn / cm. 34. Polymer mixture according to claim 33, characterized in that it in the form of a surface of a biomedical in contact with blood Device or part of it is present. 35. Polymer mixture according to claim 33, characterized in that the Polymer additive is a graft copolymer. 36. Polymer mixture according to claim 33, characterized in that the Polymer additive is a block copolymer. 37. Polymer mixture according to claim 33, characterized in that the The base polymer is a polyurethane. 38. Process for the production of a polymer mixture compatible with blood, characterized in that (a) at most 5 volumes of a polymer additive in at least 95% by volume of a base polymer can be thoroughly dispersed while adding the polymer and the base polymer is in liquid form, and a polymer blend is formed is, wherein the polymer additive contains a polydialkylsiloxane segment component, which is chemically bonded to a polyurethane segment, and the polymer additive has a value for y, c which is below the corresponding value for the base polymer and the polymer blend has a value; Yc between about 10 and 35 dynes / cm and (b) solidifying the polymer blend. 39. Compatible with blood polymer, characterized in that it is in solid form at 37 "C and is a block polymer including a sequence of block segments of the formula [A] [B] [Ci comprises, in which A is a polyalkylsiloxane, B is a hard block polymer segment with a crystal melting temperature above 37 "C or a glass transition temperature of 370 cm and C represents a hydrophile Polymer is from the group of polyethylene oxide and polyethylene oxide-copolypropylene oxide. 40. Polymer according to claim 39, characterized in that it is with a blood-incompatible base polymer in a ratio of at least 95% by volume Base polymer and a maximum of 5% by volume of polymer additive is added.