WO2009114619A1

WO2009114619A1 - Shear cell for determining physical properties of materials

Info

Publication number: WO2009114619A1
Application number: PCT/US2009/036812
Authority: WO
Inventors: Thomas G. Mason
Original assignee: The Regents Of The University Of California
Priority date: 2008-03-11
Filing date: 2009-03-11
Publication date: 2009-09-17

Abstract

A system for determining a physical property of a material includes a baseplate; a second plate arranged proximate and substantially parallel to the baseplate with a space reserved between the baseplate and the second plate that is suitable to accommodate the material; a drive system attached to the second plate, the drive system having a structure suitable to drive the second plate in an unsteady motion substantially in a plane parallel to the baseplate such that a separation distance between the baseplate and the second plate remains substantially constant during the unsteady motion; an illumination system arranged to illuminate the material during operation with illumination radiation having an illumination spectrum; and a detection system arranged to detect scattered radiation from the material. The physical property of the material is determined based on scattered radiation detected by the detection system while the drive system causes the second plate to move in the unsteady motion.

Description

SHEAR CELL FOR DETERMINING PHYSICAL PROPERTIES OF MATERIALS

CROSS-REFERENCE OF RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No. 61/064,551 filed March 11, 2008, the entire content of which is hereby incorporated by reference.

BACKGROUND

1. Field of Invention

[0002] The current invention relates to systems for altering and/or determining physical properties of materials, and more particularly systems having a shear cell for altering and/or determining physical properties of materials.

2. Discussion of Related Art

[0003] Over the past century, much attention has been paid to the rupturing of single isolated droplets by a shear flow. In a set of classic experiments in the 1930's, G.I. Taylor studied the rupturing of droplets in a device, known as a "four roll mill", which creates a controllable extensional shear flow and provides optical access to examine the shape of the droplet. From these studies, Taylor showed that a droplet of one simple liquid in another immiscible liquid could be stretched out by a shear flow, and the stretched droplet would then undergo a capillary instability driven by surface tension to rupture into smaller droplets. The size of the smaller droplets was governed by balancing the applied viscous stress with the Laplace pressure required to deform a droplet. Since the viscous stress is equal to the viscosity times the strain rate, and the Laplace pressure scale is simply given by the surface tension divided by the droplet radius, Taylor showed that the ruptured droplet size is inversely proportional to the applied shear rate.

[0004] Although Taylor's studies, and many other subsequent investigations, have provided a very clear picture of the rupturing of isolated droplets in Newtonian viscous liquids, a big gap remains in our understanding of how rupturing occurs in concentrated emulsions. By contrast to dilute emulsions, in which the assumption of isolated droplets is reasonable, in concentrated emulsions, the droplet volume fraction is large enough that droplets interact strongly with their neighbors and can even deform. As a result of these interactions, which can store energy, concentrated emulsions are soft viscoelastic materials that possess a substantial shear rigidity and a yield stress. Previous investigations (Emulsification in Viscoelastic Media, T.G. Mason and J. Bibette, Phys. Rev. Lett. 11, 3481-3481 (1996); Shear Rupturing of Droplets in Complex Fluids, T.G. Mason and J. Bibette, Langmuir 13, 4600-4612 (1997); Osmotic Pressure and Viscoelastic Shear Moduli of Monodisperse Emulsions, T.G. Mason, M. -D. Lacasse, D. Levine, G.S. Grest, J. Bibette, and D. A. Weitz, Phys. Rev. E 56, 3150-3166 (1997)) on the rheology of concentrated microscale emulsions have shown that the onset of elasticity can be associated with random close packing, which occurs at a droplet volume fraction above roughly 0.64. In these prior studies, the shear rates were always so low that the possibility of droplet rupturing was precluded. Therefore, the droplet size distribution really didn't change as a result of the applied shear. However, it is quite likely that the non-Newtonian rheology of concentrated emulsions would cause a strong modification to the inverse scaling relationship between droplet size and shear rate that Taylor deduced for isolated droplets. At present, a physical fluid dynamics problem of this complexity, which includes free-boundary flow and deformation of many curved interfaces, is presently beyond the reach of simulations.

[0005] In previous work by many researchers in the field of complex fluids, time- averaged light, neutron, and x-ray scattering observations of concentrated dispersions of uniformly sized spherical colloids, such as hard spheres, charged spheres, microgel beads, and multi-lamellar vesicles when subjected to unidirectional steady shear, commonly show peaks in the scattered intensity characteristic of positional ordering. These observations apply to systems in which shear banding can be neglected and in which the gap between the solid surfaces of the shearing device is typically at least one order of magnitude larger than the diameter of the colloids. For more highly confined hard sphere dispersions excited by oscillatory shear, optical confocal microscopy has revealed stripe-like lines and voids of spheres aligned along the direction of shear with periodicities resulting from the self-avoidance of moving chains of hard spheres (Shear- Induced Configurations of Confined Colloidal Suspensions, I. Cohen, T.G. Mason, and D.A. Weitz, Phys. Rev. Lett. 93 046001/1-4 (2004)). In all of these systems, deformation of the dispersed objects was not directly observed and therefore could not be connected to changes in positional structure. Although droplet ordering has been observed in concentrated emulsions created by controlled unidirectional shear flows (Shear Rupturing of Droplets in Complex Fluids, T.G. Mason and J. Bibette, Langmuir 13, 4600-4612 (1997); Osmotic Pressure and Viscoelastic Shear Moduli of Monodisperse Emulsions, T.G. Mason, M.- D. Lacasse, D. Levine, G.S. Grest, J. Bibette, and D.A. Weitz, Phys. Rev. E 56, 3150-3166 (1997)) the dynamic changes to droplet shape and coordination that can occur during oscillatory shear flows remains unexplored. Therefore, there remains a need for improved systems for determining physical properties of materials.

SUMMARY

[0006] A system for determining a physical property of a material according to some embodiments of the current invention includes a baseplate; a second plate arranged proximate and substantially parallel to the baseplate with a space reserved between the baseplate and the second plate that is suitable to accommodate the material; a drive system attached to the second plate, the drive system having a structure suitable to drive the second plate in an unsteady motion substantially in a plane parallel to the baseplate such that a separation distance between the baseplate and the second plate remains substantially constant during the unsteady motion; an illumination system arranged to illuminate the material during operation with illumination radiation having an illumination spectrum; and a detection system arranged to detect scattered radiation from the material. The physical property of the material is determined based on scattered radiation detected by the detection system while the drive system causes the second plate to move in the unsteady motion.

[0007] A system for producing a fine emulsion from a coarse emulsion according to some embodiments of the current invention includes a baseplate; a second plate arranged proximate and substantially parallel to the baseplate with a space reserved between the baseplate and the second plate that is suitable to accommodate an emulsion for processing; a drive system attached to the second plate, the drive system having a structure suitable to drive the second plate in an unsteady motion substantially in a plane parallel to the baseplate such that a separation distance between the baseplate and the second plate remain substantially constant during the unsteady motion; and a material supply system connected to at least one of the baseplate and the second plate so that it can supply the emulsion to the space reserved between the baseplate and the second plate. The unsteady motion of the second plate relative to the baseplate provides shear flow to stretch and rupture droplets of the coarse emulsion, thereby producing a fine emulsion having a smaller average droplet size than an average droplet size of the coarse emulsion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Further objectives and advantages will become apparent from a consideration of the description, drawings, and examples.

[0009] Figure 1 is a schematic illustration of a system for determining a physical property of a material according to an embodiment of the current invention. A first transparent window attached to the lower baseplate is opposite a second transparent window attached to the upper second plate.

[0010] Figure IA is a photograph of a system for determining a physical property of a material according to an embodiment of the current invention. It is a view of the apparatus looking down from the top showing the clear glass windows and the cross-roller bearings (pairs of silver rails). The large silver circle is a holder for the screen (and the screen is not shown). The image is taken from the CCD camera in the schematic (Figure 1) with the screen removed. Normally the CCD has a lens that focuses on the screen, but here the focus is on the plates and windows. One can see a small circle with a piece of tubing showing the injection place in the lower window attached to the fixed baseplate. The emulsion is injected into the gap through this hole and tubing.

[0011] Figure 2 shows an example of a scattering pattern of laser light detected on a screen after shearing an oil-in-water emulsion stabilized by a non-ionic surfactant according to an embodiment of the current invention. The shear direction is horizontal with respect to the scattering pattern as shown on the page. In this image, the scattered light intensity of a red laser is denoted by red color since a color camera was used to record the image, and the image has been digitally altered to turn the black background to a white background. Here, the white background indicates that no scattered laser light intensity was measured in those regions that are white. [0012] Figure 3 are scattering patterns taken during shear of the emulsion that show anisotropy in the peak intensities characteristic of droplet ordering, deformation, and tilting according to an embodiment of the current invention. The arrows indicate the direction of instantaneous shear and shear rates that are given below each panel. Computer calculations of intensities from these images can be used to determine the average droplet diameter, polydispersity in the diameter, degree of ordering or disordering of the positions of the droplets, and the deformation and tilt of the droplets. Here the emulsion droplet volume fraction is 0.70. In this image, since a monochrome camera was used to record the image, the scattered light intensity is denoted by white color, and the black background indicates that no scattered light intensity was measured in those regions that are black.

DETAILED DESCRIPTION

[0013] Some embodiments of the current invention are discussed in detail below, hi describing embodiments, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. A person skilled in the relevant art will recognize that other equivalent components can be employed and other methods developed without departing from the broad concepts of the current invention. All references cited herein are incorporated by reference as if each had been individually incorporated.

[0014] To overcome these and/or other limitations, we introduce a method of phase- resolved light scattering (PR-LS) of soft colloids subjected to oscillatory shear according to some embodiments of the current invention. Depending upon the shearing conditions, the observed PR-LS patterns can be highly anisotropic and can exhibit rings and peaks characteristic of glassy and ordered positional structures, respectively. These phase-resolved scattering patterns clearly reveal that the deformation of the droplets as well as their ensemble-average positional structure depend upon the phase of the oscillation. Moreover, by abruptly stopping the shear at different phases during an oscillation, it is possible to quench-in different degrees of order or disorder that depend primarily on the shear rate and not on the frequency.

[0015] Figure 1 provides a schematic illustration of a system 100 for determining a physical property of a material according to some embodiments of the current invention (see also Figure IA). The system 100 has a baseplate 102, a second plate 104 arranged proximate and substantially parallel to the baseplate 102 with a space reserved between the baseplate and the second plate that is suitable to accommodate the material 106, and a drive system 108 attached to the second plate 104. The drive system 108 has a structure that is suitable to drive the second plate 104 in an unsteady motion substantially in a plane parallel to the baseplate 102 such that a separation distance between the baseplate 102 and the second plate 104 remains substantially constant during the unsteady motion. The system 100 for determining a physical property of a material also has an illumination system 110 arranged to illuminate the material 106 during operation with illumination radiation having an illumination spectrum and a detection system 112 arranged to detect scattered radiation from said material 106. The physical property of the material 106 is determined based on scattered radiation detected by the detection system 112 while the drive system 108 causes the second plate 104 to move in the unsteady motion.

[0016] The baseplate 102 can have a first solid window 114 that is substantially transparent to the illumination radiation and the second plate 104 can have a second solid window 116 that is substantially transparent to the scattered radiation according to some embodiments of the current invention. The term "substantially transparent" to the illumination radiation is intended to mean enough radiation passes through the first solid window 114 to illuminate the material 106 which results in scattered radiation that passes through the second window 116 in a sufficient amount to be detected and used in the system 100. In some embodiments of the current invention, the elastic shear modulus of the material 106 can be less than an elastic shear modulus selected for the first solid window 114 and/or the second solid window 116.

[0017] The illumination radiation can be at least one of electromagnetic radiation, x-ray radiation, neutron radiation, electron radiation, positron radiation, or ion radiation according to some embodiments of the current invention. Consequently, the first solid window 114 and second solid window 116 can be selected of appropriate materials and of appropriate structure to be substantially transparent for the particular type of radiation that is provided by the illumination system 110. Figure 1 shows only one example in which the illumination system 110 provides electromagnetic radiation. The illumination system 110 can also be constructed to provide a substantially collimated beam of coherent radiation having a substantially monochromatic energy spectrum according to some embodiments of the current invention. For example, illumination system 110 can provide light from a laser 118 and thus the first solid window 114 and second solid window 116 can be glass windows. The illumination system can also include beam shaping, focusing, and/or beam reflecting components, depending on the particular application.

[0018] The concepts of the current invention are not limited to only electromagnetic sources, are not limited to only optical sources and are not limited to only laser sources. In addition, the scattered radiation can be forward scattered radiation and/or backward scattered radiation according to some embodiments of the current invention. Figure 1 shows an example of forward scattered radiation in the form of forward scattered electromagnetic radiation being detected. The scattered radiation can consist essentially of singly scattered and/or multiply scattered radiation in some embodiments of the current invention. The illumination system can also be arranged and/or the detection system structured or arranged so that unscattered, direct radiation is not detected along with scattered radiation in the detection system.

[0019] The drive system 108 can include a motor 120 with a suitable linking assembly

122 to connect the motor 120 to the second plate 104 in an embodiment of the current invention. However, the broad concepts of the current invention are not limited to only this particular example of a drive system. For example, other drive systems can include, but are not limited to, linear motors, piezoelectric transducers, resonant piezoelectric motors, non-resonant piezoelectric motors, rotary motors with mechanical couplings to convert to linear motion, hydraulic actuators, electromechanical actuators, magnetic actuators, moving coil actuators, and actuators involving a lead screw, ball screw, segmented spindle, and/or worm gear. The drive system 108 can drive the second plate 104 in a periodic motion relative to the baseplate 102 according to some embodiments of the current invention. Furthermore, the periodic motion can be substantially sinusoidal motion according to some embodiments of the current invention. According to some embodiments, the drive system 108 can actuate motion of the second solid window 1 16 in a transverse, substantially linear displacement relative to the first solid window 114. However, the broad concepts of the invention are not limited to only linear, one- dimensional motion of the second plate 104 relative to the baseplate 102. For example, other embodiments can include two-dimensional motion of the second plate 104 relative to the baseplate 102. The motion of the second plate 104 relative to the baseplate 102 can cause the material 106 to be sheared in a substantially uniform shear flow according to some embodiments of the current invention. The broad concepts of the invention are not limited to a fixed separation distance between the second plate 104 and the baseplate 102. For example, other embodiments can include a mechanical system for varying the separation between the second plate 104 and the baseplate 102 that can be used to substantially alter the separation distance.

[0020] The system 100 for determining a physical property of a material 106 according to some embodiments of the current invention can further comprising a control system (not shown in Figure 1) constructed and arranged to control at least one of a time-dependent relative motion of the second plate 104 relative to said first platelO2, an amplitude of an applied strain, an amplitude of an applied stress, a frequency of an applied strain, a frequency of an applied stress, a detector position, a detector sensitivity, an illumination position, an illumination power, an illumination spectrum, a volume injection rate of the material 106, and/or a gap separation between the second plate 104 and the baseplate 102. In some embodiments of the current invention, the separation distance between the first solid window 114 and the second solid window 116 can be uniform to within about ten percent of the separation distance. The separation distance between the baseplate 102 and the second plate 104 can be at least about 10 nm and less than about 1 mm according to some embodiments of the current invention.

[0021] The detection system 112 can include an imaging detector to provide a sequence of two dimensional images of scattering patterns of the scattered radiation over a period of time while the drive system 108 causes the second solid window 116 to move relative to the first solid window 114 according to some embodiments of the current invention. For example, the detection system 112 can include a screen 124 and a video camera 126 according to some embodiments of the current invention. The video camera can be a digital video camera, a charge coupled device (CCD) camera, a CMOS camera, a fast camera, or any other kind of array detector that is sensitive to the scattered radiation and can provide an image. According to some embodiments of the current invention, the camera can detect and store individual two- dimensional images of the pattern of scattered radiation at a rate that is typically much larger than the frequency of oscillation of the second plate, providing a time-resolved movie of the scattering pattern. The screen can include a portion of material that is at least one of absorbing, opaque, and reflective to the radiation to block out unscattered radiation in some embodiments of the current invention. [0022] The system 100 for determining a physical property of a material 106 according to some embodiments of the current invention can further include a material supply system 128 connected to the baseplate 102 to supply material 106 into the space reserved between the baseplate 102 and the second plate 104. The material supply system 128 can include a syringe pump 130 and suitable tubing 132 in some embodiments. In some embodiments, the material supply system 128 can include a plurality of syringe pumps (not shown in Figure 1) and suitable tubing, for example. In other embodiments, the material supply system 128 can include at least one of a progressing cavity pump, a peristaltic pump, a gear pump, a centrifugal pump, a piston pump, a diaphragm pump, a hydraulic pump, and a dispensing pump. In some embodiments, the syringe pump 130, or plurality of syringe pumps, can be operated by a controller and/or computer. The material supply system 128 is suitable to deliver a fluid material 106 to the space reserved between the baseplate 102 and the second plate 104. The fluid material 106 can be, but is not limited to, a simple liquid, a suspension, a slurry, a liquid material, a viscoelastic material, a viscoplastic material, a thixotropic material, a pseudoplastic material, a dilatant material, a plastic material, a complex fluid, a dispersion, a nanoparticulate dispersion, a microparticulate dispersion, an emulsion, a nanoemulsion, a foam, a lyotropic liquid crystalline phase, a liquid crystal, a polymer solution, a polymer blend, a polymer melt, a micellar solution, a protein solution, a co-polymer material, a biological material, and a non-Newtonian fluid, or a combination thereof.

[0023] The system 100 for determining a physical property of a material 106 according to some embodiments of the current invention can further include a signal processing system that is in communication with said detection system 112, the drive system 108, the illumination system 110 and/or the material supply system 128. The signal processing system can process signals based on scattered radiation detected by the detection system 112 to provide the physical property of the material 106. The material 106 can be a fluid material that comprises colloidal objects in at least one of a suspension or an emulsion according to some embodiments of the current invention and the physical property determined can correspond to at least one of a deformability, a fission, a fusion, a disaggregation, an aggregation, a rotation, a vibration, and a positional rearrangement of the colloidal objects.

[0024] The system 100 for determining a physical property of a material 106 according to some embodiments of the current invention can further include a tracking system arranged to track motion of the second plate 104 relative to the first plate 102 while the second plate 104 is driven in an unsteady motion by the drive system 108. The tracking system can be in communication with the signal processing system to determine the physical property taking into account at least one of a relative position and a motion of the second plate 104 relative to the baseplate 102. The material supply system 128 can be in communication with the signal processing system to be controlled based on information obtained from detected signals of radiation scattered from the material 106 in the space reserved between the baseplate 102 and the second plate 104.

[0025] The system 100 can also be adapted to provide a system for processing material.

Various combinations of the components of the system 100 can be included for processing material, as is suitable for the particular application. The apparatus can alter the structure of a soft material, such as an emulsion, through flow-induced effects, and also simultaneously probe a physical property, such as the structure, of the soft material as it is being altered by the flow. The apparatus is particularly suited for generating a transverse shear flow through the relative motion of the plates, but, in addition, a component of extensional flow may also be present due to the injection of the soft material into the space reserved (i.e. gap) between the plates. Although many types of unsteady shearing flows can be created, a periodic shear flow is typically employed, and in particular a periodic sinusoidal shear flow. In some embodiments of the current invention, to generate droplet rupturing, the maximum strain amplitude of the shear flow is greater than unity, and typically it is much greater than unity. It is possible to efficiently recover the fine emulsion, and typically the injection rate is adjusted so that at least several cycles of oscillation have occurred before an injected volume of coarse emulsion leaves the space reserved as a fine emulsion.

EXAMPLE

[0026] The system 100 can provide a PR-LS apparatus according to an embodiment of the current invention that combines a time-resolved light scattering apparatus with a transparent parallel -plate oscillatory shear cell (see Figure 1). The first solid window 114 and the second solid window 116 of the system 100 provide a transparent parallel-plate oscillatory shear cell in this example. In this example, optically flat glass plates (i.e. the second and first solid windows, respectively) are held by upper and lower metal frames (i.e. the second plate and baseplate, respectively); the stationary lower plate is mounted to the upper plate using crossed roller bearings attached to a rail-in-groove system with a compressible plastic spacer and a series of screws that provide tip-tilt and separation control and that maintain parallelism. A computer- controlled brushless motor rotates at frequency/and a slider linkage attached to the shaft provides an independent control over the maximum excursion of sinusoidal oscillations of the upper plate, x_maκ, thereby setting the maximum strain χ_max = x_mαx/h, where h is the separation between the upper and lower plates in which the complex fluid is injected. Thus, through the independent control over/and x_max, the maximum instantaneous strain rate that is generated is Error! Objects cannot be created from editing field codes.= 2πfχ_max. The separation h between the upper and lower plates is tuned by a tip-tilt adjustment to be 100 ± 10 μm typically, and usually between 30 μm and 1 mm. Although other optical sources, such as light emitting diodes could be used, a helium-neon laser beam of about 0.5 mm beam waist is reflected by a mirror up through the complex fluid that is injected between the plates by a syringe that can be controlled by a computer-controllable syringe pump, and the scattered light illuminates a screen. A charge-coupled device (CCD) camera (or other camera such as a high-speed CMOS camera) connected to a computer-controlled frame grabber simultaneously records the scattering intensity / as a function of spatial coordinates (x,y) of the area imaged on the screen, and also the position of the upper plate, through a reflection due to a second kind of optical illumination that reflects off of a reflector mounted on the upper plate. Thus, a movie of the changing scattering patterns can be directly associated with the instantaneous phase ψ = 2τφ:, where t is the time (e.g. t = 0 at the start of the oscillations), of the imposed shear oscillations. We have verified the linearity of the intensities in the recorded patterns. Alternatively, the screen is optional, and the scattered radiation can be detected directly by the array detector without the need for a translucent screen.

[0027] Although we have used a simple rotary motor and a crank-shaft mechanism to create oscillatory motion of the upper plate along one linear direction, other means of actuation could also be used, including piezoelectric actuation and linear positioning stages and actuators that are commonly sold. Likewise, the helium-neon (He-Ne) laser source could be another source of a collimated light beam, including a different type of laser at a different wavelength (e.g. wavelength-tunable diode laser), multiple lasers at different wavelengths, light emitting diodes, or even optical parametric oscillators. Likewise, many types of cameras, camera- computer interfaces, computers, and image processing software could be used to implement various embodiments of the current invention.

[0028] We have performed PR-LS experiments on nonionically stabilized oil-in-water emulsions that are injected between the two plates. The concentrated emulsion consists of a dispersed droplet phase of silicone oil (polydimethylsiloxane, 350 cP) and a continuous phase of nonionic surfactant Tergitol NP-7 at 40 wt% in water. At room temperature 22 °C, the continuous phase has a measured viscosity h_c= 600 cP and is Newtonian. The surfactant concentration is chosen so that shear banding is eliminated (Shear Rupturing of Droplets in Complex Fluids, T.G. Mason and J. Bibette, Langmuir 13, 4600-4612 (1997); Osmotic Pressure and Viscoelastic Shear Moduli of Monodisperse Emulsions, T.G. Mason, M. -D. Lacasse, D. Levine, G.S. Grest, J. Bibette, and D.A. Weitz, Phys. Rev. E 56, 3150-3166 (1997)). Moreover, the two phases have nearly matching refractive indices n = 1.40 so the emulsion is somewhat transparent and can be probed by light scattering techniques. In order to probe shear-induced rupturing of strongly interacting droplets in concentrated emulsions, we have created an injection parallel-plate oscillatory shear cell with light scattering or other optical probes to examine the droplet structures while an oscillatory shear is applied (see Figure 1). A computer- controlled syringe pump injects a crudely premixed emulsion of very large droplets (e.g. up to 50 micron size). The composition of the emulsion can be silicone oil-in-water, stabilized by a variety of surfactants: ionic, nonionic, and zwitterioinic. We tested the shear cell with nonionic surfactants such as ethoxylated NP-7 in water as the continuous phase surrounding dispersed droplets of poly-dimethylsiloxane (PDMS) silicone oil. The large droplets are injected between the two plates and a camera records videos of the scattering pattern of laser light falling onto a screen. These videos are processed by the computer connected to the frame grabber (or other camera input device e.g. USB, firewire, etc.), and calculations based on the patterns of the data can reveal the degree of droplet size (position of a ring or spots), degree of droplet positional order or disorder (spot intensities vs ring intensities), droplet stretching and tilting (through left- right anisotropy in intensity during shear at particular phases). This information can be rapidly calculated and estimated, and the results can be provided to the user typically after only a few oscillations. As far as droplet rupturing is concerned, we can obtain droplets with diameters in the range from a few tenths of a micron to about ten microns, well within the range that small angle light scattering (SALS) can probe. Index matching liquids, such as glycerol, in the continuous aqueous phase can be used in order to facilitate single scattering experiments. [0029] After rupturing droplets at a higher frequency, subsequently shearing the emulsion at lower/can order the droplets to varying degrees after just a few oscillations, creating more complex scattering patterns that can show primary peaks that are hexagonally arranged and are effectively mirror symmetric with respect to the shear direction (Figure 2); the upper and lower halves of the scattering pattern are practically mirror images. During the oscillations, the intensities of the right and left pairs of peaks become alternatively stronger and weaker periodically (Figure 3). Middle peaks dominate as the velocity of the upper plate is near its maximum, and left and right peaks alternate in dominance when the upper plate is moving in left and right directions, respectively. (See also, Shear oscillation light scattering of droplet deformation and reconfiguration in concentrated emulsions, J. -R. Huang and T. G. Mason, EPL, 83 (2008) 28004, the entire contents of which are incorporated herein by reference.)

[0030] Some embodiments of this invention can be used for detecting the deformability, orientation, jamming, interaction, and anisotropy of dispersed colloidal objects, such as emulsions and lithographic particles that are at high concentrations through the shear-induced response of the light scattering patterns. This method can provide advantages over confocal microscopy techniques that are typically not capable of reaching high enough speeds to be useful for determining these properties of the particles or droplets at very large flow rates required to observe some of these phenomena.

[0031] The zone of maximal shear is the region between the second plate and the baseplate wherein the separation distance between the two plates is minimal and highly uniform, and the material experiences the maximum shear rate. The instantaneous shear rate is the ratio given by the instantaneous velocity of the second plate relative to the baseplate divided by the separation distance between the second plate and the baseplate. The zone of maximal shear lies substantially in the space reserved between the two plates. Although the minimal separation distance between the second plate and the baseplate corresponding to the zone of maximal shear is typically between 10 nm and 1 mm, it is not necessary and frequently even not desirable for the separation distance over the entire surface area of the second plate to lie in this range. Typically, it is more convenient to mount a first solid window in the baseplate and a second solid window in the second plate, and to use a tip-tilt mechanism, compressive spring element, or other means of mechanical adjustment to control the separation distance and degree of parallelism between the first solid window and the second solid window before injecting the material. Typically the surfaces of the first solid window and the second solid window are very smooth and flat, and they are attached to the baseplate and second plate, respectively, without creating stresses that could cause the windows to deform significantly.

[0032] When processing and altering a material, while simultaneously detecting a change in the structural properties of the material, it can be desirable to further control the flow of the material in the zone of maximal shear by inserting two strips of low-friction teflon film, which has a thickness that is highly uniform, between the first solid window and the second solid window. These strips can be used to inhibit the flow of any injected material out of the side gaps between the edges of the windows that lie parallel to the shear direction, and channel the flow of material out of the end gaps between the edges of the windows that lie perpendicular to the shear direction. When operating the device using a continuous volume flow rate of material injection, the material altered by the unsteady flow emerges from the end gaps and is collected and retained. For an embodiment wherein the baseplate is made of metal, it can be useful to machine slots or holes in the baseplate in order to allow the material altered by the unsteady flow to gravitationally drop into a collection reservoir.

[0033] Typical ranges of operation of a number of controllable parameters of the apparatus are as follows. The minimum separation distance between the baseplate and the second plate is typically between about 10 nm and about 1 mm. The maximum strain amplitude generated by the unsteady relative motion of the second plate with respect to the baseplate is typically between about 10^"3 and 10⁶. The maximum strain rate generated by the unsteady relative motion of the second plate with respect to the baseplate is typically between about 10^~5 s^"1 and about 10⁷ s^"1. The maximum frequency of a periodic unsteady relative motion of the second plate with respect to the baseplate is typically between about 10^~6 Hz and about 10⁵ Hz. The volume injection rate of the material into the zone of maximal shear is typically between 0 (zero) mL/min and about 10⁵ mL/min. The frame rate of the area detector is typically between about 10^~2 Hz and about 10⁶ Hz. The exposure time of the area detector per frame multiplied by the frame rate of the detector is typically between about 10^"4 and about 1. The number of pixels of the area detector is typically between about 10² and about 10⁹. The distance between the material in the zone of maximal shear and the detection screen is typically between about 1 mm and about 10³ mm. The distance between the material in the zone of maximal shear and the array detector is typically between about 1 mm and about 10⁵ mm. [0034] In an embodiment wherein visible coherent laser light is used as the illuminating radiation, the area of the smooth and flat surface of the second solid window is typically between about 1 mm² and about 10⁵ mm². The effective diameter (i.e. beam waist) of the collimated beam of illuminating radiation is typically between about 10^~6 mm² and about 10² mm². In an embodiment wherein coherent x-ray radiation is used as the illuminating radiation, microbeam x-ray illumination can be used. In an embodiment wherein pulsed illuminating radiation is used, such as for a neutron beam generated by a spallation neutron source, a periodic unsteady motion of the second plate relative to the baseplate can be synchronized with the pulsing of the illuminating source radiation using an electronic control system in order to record scattering patterns over the entire phase of an unsteady periodic relative motion of the second plate with respect to the first plate.

[0035] In describing embodiments of the invention, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected. The above-described embodiments of the invention may be modified or varied, without departing from the invention, as appreciated by those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the claims and their equivalents, the invention may be practiced otherwise than as specifically described.

Claims

WE CLAIM:

1. A system for determining a physical property of a material, comprising: a baseplate; a second plate arranged proximate and substantially parallel to said baseplate with a space reserved between said baseplate and said second plate that is suitable to accommodate said material; a drive system attached to said second plate, said drive system having a structure suitable to drive said second plate in an unsteady motion substantially in a plane parallel to said baseplate such that a separation distance between said baseplate and said second plate remains substantially constant during said unsteady motion; an illumination system arranged to illuminate said material during operation with illumination radiation having an illumination spectrum; and a detection system arranged to detect scattered radiation from said material, wherein said physical property of said material is determined based on scattered radiation detected by said detection system while said drive system causes said second plate to move in said unsteady motion.

2. A system for determining a physical property of a material according to claim 1 , wherein said baseplate comprises a first solid window that is substantially transparent to said illumination radiation and said second plate comprises a second solid window that is substantially transparent to said scattered radiation.

3. A system for determining a physical property of a material according to claim 1 or 2, wherein said illumination radiation is at least one of electromagnetic radiation, x-ray radiation, neutron radiation, electron radiation, positron radiation, and ion radiation.

4. A system for determining a physical property of a material according to any one of claims 1 to 3, wherein said scattered radiation is at least one of forward scattered radiation and backward scattered radiation.

5. A system for determining a physical property of a material according to any one of claims 1 to 4, wherein said unsteady motion is a periodic motion.

6. A system for determining a physical property of a material according to any one of claims 1 to 5, wherein said periodic motion is substantially a sinusoidal oscillatory motion.

7. A system for determining a physical property of a material according to any one of claims 1 to 6, wherein an elastic shear modulus of said material is less than an elastic shear modulus of said solid window.

8. A system for determining a physical property of a material according to any one of claims 1 to 7, wherein said drive system actuates motion of said second solid window in a transverse displacement relative to said first solid window.

9. A system for determining a physical property of a material according to any one of claims 1 to 8, wherein said illumination system is constructed to provide a substantially collimated beam of coherent radiation having a substantially monochromatic energy spectrum.

10. A system for determining a physical property of a material according to any one of claims 1 to 9, wherein said relative motion of said second plate relative to said baseplate causes said material to be sheared in a substantially uniform shear flow.

11. A system for determining a physical property of a material according to any one of claims 1 to 10, wherein said scattered radiation consists essentially of at least one of singly scattered radiation and multiply scattered radiation.

12. A system for determining a physical property of a material according to any one of claims 1 to 11, further comprising a control system constructed and arranged to control at least one of a time-dependent relative motion of said second plate relative to said first plate, an amplitude of an applied strain, an amplitude of an applied stress, a frequency of an applied strain, a frequency of an applied stress, a detector position, a detector sensitivity, an illumination position, an illumination power, an illumination spectrum, a volume injection rate of said material into said space reserved, and a gap separation between said second plate and said baseplate.

13. A system for determining a physical property of a material according to any one of claims 1 to 12, wherein said separation distance between said first solid window and said second solid window is uniform to within about ten percent of said separation distance.

14. A system for determining a physical property of a material according to any one of claims 1 to 13, wherein said separation distance between said baseplate and said second plate is at least about 10 nm and less than about 1 mm.

15. A system for determining a physical property of a material according to any one of claims 1 to 14, wherein said detection system comprises an imaging detector to provide a sequence of two dimensional images of scattering patterns of said scattered radiation over a period of time while said drive system causes said second solid window to move relative to said first solid window in said unsteady motion.

16. A system for determining a physical property of a material according to any one of claims 1 to 15, wherein said illumination system comprises a laser arranged to illuminate said material with a beam of laser light that illuminates at least a portion of said material between said baseplate and said second plate.

17. A system for determining a physical property of a material according to any one of claims 1 to 16, further comprising a material supply system connected to said baseplate to supply material into said space reserved between said baseplate and said second plate.

18. A system for determining a physical property of a material according to claim 17, wherein said material supply system is suitable to deliver a fluid material to said space reserved between said baseplate and said second plate.

19. A system for determining a physical property of a material according to claim 18, wherein said fluid material is at least one of a simple liquid, a suspension, a slurry, a liquid material, a viscoelastic material, a viscoplastic material, a thixotropic material, a plastic material, a complex fluid, a dispersion, a nanoparticulate dispersion, a microparticulate dispersion, an emulsion, a nanoemulsion, a foam, a lyotropic liquid crystalline phase, a liquid crystal, a polymer solution, a polymer blend, a polymer melt, a micellar solution, a protein solution, a copolymer material, a biological material, and a non-Newtonian fluid, or a combination thereof.

20. A system for determining a physical property of a material according to any one of claims 1 to 19, further comprising a signal processing system in communication with said detection system, wherein said signal processing system processes signals based on scattered radiation detected by said detection system to provide said physical property of said material.

21. A system for determining a physical property of a material according to claim 20, wherein said fluid material comprises colloidal objects in at least one of a suspension or an emulsion and said physical property determined corresponds to at least one of a deformability, a rotation, and a positional rearrangement of said colloidal objects.

22. A system for determining a physical property of a material according to claim 20, further comprising a tracking system arranged to track motion of said second plate relative to said first plate while said second plate is driven in an unsteady motion by said drive system, wherein said tracking system is in communication with said signal processing system to determine said physical property taking into account at least one of a relative position and a motion of said second plate relative to said baseplate.

23. A system for determining a physical property of a material according to any one of claims 17 to 22, wherein said material supply system is in communication with said signal processing system to be controlled based on information obtained from detected signals of radiation scattered from said material in said space reserved between said baseplate and said second plate.

24. A system for determining a physical property of a material according to any one of claims 1 to 23, wherein said first solid window and said second solid window are substantially optically flat with respect to light within said illumination spectrum, and wherein said first solid window and said second solid window are sufficiently transparent to light within said illumination spectrum such that said detection system can detect light that passes through at least one of said base plate or said second plate to illuminate said material and is subsequently scattered by said material, said scattered light passing through the other one of said baseplate or said second plate.

25. A system for altering and determining simultaneously a physical property of a material according to any one of claims 1 to 23.

26. A system for producing a fine emulsion from a coarse emulsion, comprising: a baseplate; a second plate arranged proximate and substantially parallel to said baseplate with a space reserved between said baseplate and said second plate that is suitable to accommodate an emulsion for processing; a drive system attached to said second plate, said drive system having a structure suitable to drive said second plate in an unsteady motion substantially in a plane parallel to said baseplate such that a separation distance between said baseplate and said second plate remain substantially constant during said unsteady motion; and a material supply system connected to at least one of said baseplate and said second plate so that it can supply said emulsion to said space reserved between said baseplate and said second plate, wherein said unsteady motion of said second plate relative to said baseplate provides shear flow to stretch and rupture droplets of said coarse emulsion, thereby producing a fine emulsion having a smaller average droplet size than an average droplet size of said coarse emulsion.

27. A system for producing a fine emulsion from a coarse emulsion according to claim 26, wherein said baseplate comprises a first solid window and said second plate comprises a second solid window.

28. A system for producing a fine emulsion from a coarse emulsion according to claim 27, wherein a separation distance between said first solid window and said second solid window is uniform to within about ten percent of said separation distance.

29. A system for producing a fine emulsion from a coarse emulsion according to claim 27 or 28, wherein said separation distance between said first solid window and said second solid window is at least about 10 nm and less than about 1 mm.

30. A system for producing a fine emulsion from a coarse emulsion according to any one of claims 26 to 29, further comprising: an illumination system arranged to illuminate said emulsion with radiation having an illumination spectrum; and a detection system arranged to detect radiation scattered from said emulsion being processed to produce said fine emulsion, wherein a physical property of said emulsion is determined based on scattered radiation detected by said detection system while said drive system causes said second plate to move in said unsteady motion.

31. A system for producing a fine emulsion from a coarse emulsion according to any one of claims 26 to 30, wherein said detection system comprises an imaging detector and a recording system to provide a sequence of two dimensional images of patterns of scattered radiation over a period of time while said drive system causes said second plate to move relative to said baseplate in said unsteady motion.

32. A system for producing a fine emulsion from a coarse emulsion according to any one of claims 26 to 31 , wherein said illumination system comprises a laser arranged to illuminate said emulsion when said emulsion is present between said baseplate and said second plate.

33. A system for producing a fine emulsion from a coarse emulsion according to any one of claims 26 to 31 , further comprising a signal processing system in communication with said detection system, wherein said signal processing system processes signals based on scattered light detected by said detection system to provide control of processing said emulsion.