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PubMed2006

Effect of permeability on aqueous biopolymer interfaces in spinning drop experiments.

In this paper we show that interfaces in aqueous phase-separated biopolymer mixtures are permeable for all components present in the system. In spinning drop experiments, droplets of the low-density phase decreased up to 90% in volume over a time span of days to weeks, when inserted in a matrix of the high-density phase. We propose an expression for this change of volume in time in terms of diffusion coefficients of the components. From the magnitude of these coefficients, we conclude that the transfer of gelatin from inside the droplet to the outer phase was the rate-determining step in this process. Since the interfaces are permeable to all components, the properties of the system change in time. Therefore, the spinning drop technique is not an accurate method for the measurement of the equilibrium interfacial tension of these aqueous phase-separated systems.

Animals↗

PubMed2006

Strongly interacting Fermi gases with density imbalance.

We consider density-imbalanced Fermi gases of atoms in the strongly interacting, i.e., unitarity, regime. The Bogoliubov-de Gennes equations for a trapped superfluid are solved. They take into account the finite size of the system, as well as give rise to both phase separation and Fulde-Ferrel-Larkin-Ovchinnikov-type oscillations in the order parameter. We show how radio-frequency spectroscopy reflects the phase separation, and can provide direct evidence of the FFLO-type oscillations via observing the nodes of the order parameter.

Journal Article↗

PubMed2005

Coupling of solid-phase microextraction and capillary isoelectric focusing with laser-induced fluorescence whole column imaging detection for protein analysis.

A coupling method of solid-phase microextraction (SPME) and capillary isoelectric focusing (CIEF) with laser-induced fluorescence (LIF) whole column imaging detection (WCID) was developed for the analysis of proteins. Unlike other liquid-phase separation methods and conventional CIEF, proteins are focused into stationary bands within a pH gradient in CIEF-WCID. Thus, CIEF-WCID is the most compatible liquid-phase separation method for coupling with SPME, which can effectively resolve the problems associated with the slow desorption kinetics of SPME in a liquid phase. By combining SPME and CIEF-WCID, the desorption time can be as long as necessary, allowing complete desorption without any band broadening and analyte carryover. By using this method, R-phycoerythrin in water can be extracted by SPME in 10 min, and subsequently analyzed by CIEF-LIF-WCID within 20 min, providing a limit of detection of 3.5 x 10(-12) M (S/N = 3). The feasibility of the SPME-CIEF-LIF-WCID method was demonstrated by extracting and analyzing extracellular phycoerythrins in cultured cyanobacteria samples. Extracellular phycoerythrins at the nanomolar level were extracted and analyzed in 30 min, while avoiding the interference of the cyanobacteria cells.

Fluorescence↗

PubMed2002

Cyclodextrin-induced lipid lateral separation in DMPC membranes: (2)H nuclear magnetic resonance study.

Cholesteryl cyclodextrins, obtained by grafting a cholesterol moiety on the oligosaccharide core, combine the size selectivity of the cyclodextrin cavity with the carrier properties of model membrane systems such as micelles or liposomes. The cholesteryl cyclodextrins were incorporated as guests in chain perdeuterated dimyristoyl phosphatidylcholine (DMPC-d54) membranes. The deuterium nuclear magnetic resonance (NMR) spectra obtained with the A form of cholesteryl-beta-cyclodextrin (beta CC(A)), with a succinyl spacer inserted between the cholesterol moiety and the cyclodextrin headgroup, indicated that this compound induces a lateral phase separation of DMPC-d54, into a pure lipid phase and a cholesteryl cyclodextrin-rich phase. The lipid exchange rate between the two phases was slow on the NMR timescale (>10(-5) s), and two well-resolved spectral components could be detected. The laterally segregated mixed phase was observed at various membrane concentrations of cholesteryl cyclodextrin, even with dispersions containing only 5% of the derivative. The dePaked spectra allowed the determination of the relative amount of DMPC-d54 molecules contained in each phase, giving approximately 1 to 1.5 DMPC molecules per unit of beta CC(A). This ratio was found to be independent of the total membrane concentration of beta CC(A). The cholesteryl cylodextrin-rich phase was detected on a large range of temperature from -12 degrees C to 25 degrees C and exhibits a smooth transition from a fluid environment to a more ordered state, occurring approximately 0 degrees C. A boundary phase between the pure lipid and cyclodextrin-rich phase was detected at 19 degrees C just below the fluid-to-gel transition. The average orientational order was reduced in the cholesteryl cyclodextrin-rich phase, and quasi-independent of temperature, as opposed to the order parameters measured for the NMR signals of the pure lipid phase. However, the NMR data obtained with beta CC(A) deuterated on the cyclodextrin headgroup indicated that the latter was quasistatic, with very large order parameters (approximately 120 kHz) at all temperatures, suggesting strong interactions between neighboring cyclodextrin headgroups. The interactions of DMPC-d54 membranes with the B form of cholesteryl-beta-cyclodextrin, lacking the succinyl spacer, was also investigated in a parallel study. No lateral phase separation was found with this compound, indicating that the spatial location and a precise positioning (allowed by the spacer) of the cyclodextrin headgroup at the membrane interface was crucial for the stability of the cholesteryl cyclodextrin lamellar phase.

Biophysical Phenomena↗

PubMed1988

Globoside with spin-labelled fatty acid: bilayer lateral distribution and immune recognition.

We have critically addressed the question of lateral distribution of glycolipids in bilayer membranes, and the effect of glycolipid fatty acid chain length upon such distribution. For this purpose we synthesised the complex neutral glycosphingolipid, globoside, with spin-labelled fatty acid. Base hydrolysis to remove the natural fatty acid was found to deacetylate the GalNAc residue concomitantly, necessitating application of the synthetic route described for gangliosides by Neuenhofer et al. (Biochemistry 24, 525-532 (1985)). Globosides were produced with 18-carbon and 24-carbon fatty acids bearing a spin label at the C-16 position. Spin-labelled globosides were incorporated at 2 and 10 mol% into rigid, highly cooperative bilayer matrices of 1,2-dipalmitoylglycerophosphocholine (DPPC) and also into semi-fluid, non-cooperative membranes of DPPC/cholesterol. Recorded electron paramagnetic resonance (EPR) spectra were analysed by comparison with a library of standards representing samples of known composition. Spectra were manipulated using a computer program which permitted linear combination of standards to stimulate coexistence of laterally separated domains of different composition. The most important conclusions were as follows: (1) at least 80% of the globoside was definitely not confined to domains highly enriched in glycolipid, although there was evidence of binary-phase separation in the rigid DPPC/globoside matrix; (2) the presence of 33 mol% cholesterol reduced the evidence of globoside phase separation; (3) there was remarkably little difference in results whether the globoside fatty acid chain length was similar to that of the phospholipid host matrix or eight carbons longer. Temperature profiles derived over the phase-transition region of DPPC using spin-labelled globoside or an unattached amphiphilic spin label were consistent with these findings. The same systems lent themselves to consideration of the role of glycolipid fatty acid chan length and cholesterol in determining glycolipid crypticity in membranes: (1) polyclonal anti-globoside IgG bound to globoside in DPPC liposomes without inducing agglutination. (2) The same antibodies did agglutinate DPPC/cholesterol liposomes bearing globoside. (3) The effect of cholesterol probably was upon glycolipid dynamics or attitude in the membrane, rather than upon distribution. (4) These observations were basically unaffected by the choice of 18-carbon vs. 24-carbon glycolipid fatty acids.(ABSTRACT TRUNCATED AT 400 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1987

Hydrophobic properties of the beta 1 and beta 2 subunits of the rat brain sodium channel.

Voltage-sensitive sodium channels purified from rat brain in functional form consist of a stoichiometric complex of three glycoprotein subunits, alpha of 260 kDa, beta 1 of 36 kDa, and beta 2 of 33 kDa. The alpha and beta 2 subunits are linked by disulfide bonds. The hydrophobic properties of these three subunits were examined by covalent labeling with the photoreactive hydrophobic probe 3-(trifluoromethyl)-3-(m-[125I]iodophenyl)diazirine [( 125I]TID) which labels transmembrane segments in integral membrane proteins. All three subunits of the sodium channel were labeled by [125I]TID when the purified protein was solubilized in mixed micelles of Triton X-100 and phosphatidylcholine (4:1). The half-time for photolabeling was approximately 7 min consistent with the half-time of 9 min for photolysis of TID under our conditions. Comparable amounts of TID per mg of protein were incorporated into each subunit. Purified sodium channels reconstituted in phosphatidylcholine vesicles were also labeled by TID with comparable incorporation per mg of protein into all three subunits. The efficiency of photolabeling of the three subunits was reduced from 39 to 44% by a 2-fold expansion of the hydrophobic phase of the reaction mixture but was unaffected by a 2-fold expansion of the aqueous phase, confirming that the photolabeling reaction took place in the lipid phase of the vesicle bilayer. The hydrophobic properties of the sodium channel subunits were examined further using phase separation in the nonionic detergent Triton X-114. Under conditions in which beta 1 is dissociated from alpha, the beta 1 subunit was preferentially extracted into the Triton X-114 phase, and the disulfide-linked alpha beta 2 complex was retained in the aqueous phase. When the disulfide bonds between the alpha and beta 2 subunits were reduced with dithioerythritol, the beta 2 subunit was also preferentially extracted into the Triton X-100 phase leaving the free alpha subunit in the aqueous phase. A preparative method for isolation of the beta 1 and beta 2 subunits was developed based on this technique. Considered together, the results of our hydrophobic labeling and phase separation experiments indicate that the alpha, beta 1, and beta 2 subunits all have substantial hydrophobic domains that may interact with the hydrocarbon phase of phospholipid bilayer membranes. Since the alpha subunit is known to be a transmembrane protein with many potential membrane-spanning segments, we conclude that the beta 1 and beta 2 subunits are likely to also be integral membrane proteins with one or more membrane-spanning segments.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2001

Creating porous tubes by centrifugal forces for soft tissue application.

Chemically crosslinked poly(2-hydroxyethyl methacrylate) (PHEMA) tubes were synthesized by applying centrifugal forces to propagating polymer chains in solution. Initiated monomer solutions, with a composition typical for PHEMA sponges, were placed into a cylindrical mold that was rotated about its long axis. As polymerization proceeded, phase separated PHEMA formed a sediment at the periphery under centrifugal action. The solvent remained in the center of the mold while the PHEMA phase gelled, resulting in a tube. By controlling the rotational speed and the formulation chemistry (i.e., monomer, initiator and crosslinking agent concentrations), the tube dimensions and wall morphology were manipulated. Tube manufacture was limited by a critical casting concentration [M]c, above which only rods formed. All tubes had an outer diameter of 2.4 mm, reflecting the internal diameter of the mold and a wall thickness of approximately 40-400 microm. Wall morphologies varied from interconnecting polymer and water phases to a closed cell, gel-like, structure. Concentric tubes were successfully prepared by using formulations that enhanced phase separation over gelation/network formation. This was achieved by using formulations with lower concentrations of monomer and crosslinking agent and higher concentrations of initiator. This technique offers a new approach to the synthesis of polymeric tubes for use in soft tissue applications, such as nerve guidance channels.

Biocompatible Materials↗

PubMed2006

Nondestructive technique for the characterization of the pore size distribution of soft porous constructs for tissue engineering.

Polymer scaffolds tailored for tissue engineering applications possessing the desired pore structure require reproducible fabrication techniques. Nondestructive, quantitative methods for pore characterization are required to determine the pore size and its distribution. In this study, a promising alternative to traditional pore size characterization techniques is presented. We introduce a quantitative, nondestructive and inexpensive method to determine the pore size distribution of large soft porous solids based on the on the displacement of a liquid, that spreads without limits though a porous medium, by nitrogen. The capillary pressure is measured and related to the pore sizes as well as the pore size distribution of the narrowest bottlenecks of the largest interconnected pores in a porous medium. The measured pore diameters correspond to the narrowest bottleneck of the largest pores connecting the bottom with the top surface of a given porous solid. The applicability and reproducibility of the breakthrough technique is demonstrated on two polyurethane foams, manufactured using the thermally induced phase separation (TIPS) process, with almost identical overall porosity (60-70%) but very different pore morphology. By selecting different quenching temperatures to induce polymer phase separation, the pore structure could be regulated while maintaining the overall porosity. Depending on the quenching temperature, the foams exhibited either longitudinally oriented tubular macropores interconnected with micropores or independent macropores connected to adjacent pores via openings in the pore walls. The pore size and its distribution obtained by the breakthrough test were in excellent agreement to conventional characterization techniques, such as scanning electron microscopy combined with image analysis, BET technique, and mercury intrusion porosimetry. This technique is suitable for the characterization of the micro- and macropore structure of soft porous solids intended for tissue engineering applications. The method is sensitive for the smallest bottlenecks of the largest continuous pores throughout the scaffold that contributes to fluid flow.

Polyurethanes↗

PubMed2005

(R)-phenylacetylcarbinol production in aqueous/organic two-phase systems using partially purified pyruvate decarboxylase from Candida utilis.

Aqueous/organic two-phase systems have been evaluated for enhanced production of (R)-phenylacetylcarbinol (PAC) from pyruvate and benzaldehyde using partially purified pyruvate decarboxylase (PDC) from Candida utilis. In a solvent screen, octanol was identified as the most suitable solvent for PAC production in the two-phase system in comparison to butanol, pentanol, nonanol, hexane, heptane, octane, nonane, dodecane, methylcyclohexane, methyl tert butyl ether, and toluene. The high partitioning coefficient of the toxic substrate benzaldehyde in octanol allowed delivery of large amounts of benzaldehyde into the aqueous phase at a concentration less than 50 mM. PDC catalyzed the biotransformation of benzaldehyde and pyruvate to PAC in the aqueous phase, and continuous extraction of PAC and byproducts acetoin and acetaldehyde into the octanol phase further minimized enzyme inactivation, and inhibition due to acetaldehyde. For the rapidly stirred two-phase system with a 1:1 phase ratio and 8.5 U/mL carboligase activity, 937 mM (141 g/L) PAC was produced in the octanol phase in 49 h with an additional 127 mM (19 g/L) in the aqueous phase. Similar concentrations of PAC could be produced in the slowly stirred phase separated system at this enzyme level, although at a much slower rate. However at lower enzyme concentration very high specific PAC production (128 mg PAC/U carboligase at 0.9 U/mL) was achieved in the phase separated system, while still reaching final PAC levels of 102 g/L in octanol and 13 g/L in the aqueous phase. By comparison with previously published data by our group for a benzaldehyde emulsion system without octanol (50 g/L PAC, 6 mg PAC/U carboligase), significantly higher PAC concentrations and specific PAC production can be achieved in an octanol/aqueous two-phase system.

Acetone↗

PubMed1984

The effect of phospholipids on the activity of mitochondrial pyrophosphatases. Lipidized soluble mitochondrial pyrophosphatase: the coupling factor for oxidation and phosphorylation.

The effect of temperature on the hydrolase activity of mitochondrial pyrophosphatases, i.e. soluble (PPase I) and membrane (PPase II), has been studied. In contrast to the soluble species, the membrane form has inflexions in the Arrhenius curves. However, after lipidization of PPase I by various phospholipids, the curves also acquire inflexion points, which prove similar or identical with the phase separation points of the lipids used. The closeness of the inflexion points of PPase II, containing phosphatidylcholine, and PPase I lipidized by mitochondria phosphatidylcholine, to the phase separation points of this lipid indicates that the inflexions on the PPase II curves should be ascribed to this phospholipid. It has been shown that the hydrolysis of PPi by SMP is affected by the cooperative rearrangements of the entire lipid component of the membrane rather than by the change of the phase state of PPase II phosphatidylcholine. Reconstitution experiments on the PPi synthesis system have shown that after lipidization PPase I is able to incorporate into SMP and become a coupling factor for respiration and PPi synthesis, like PPase II.

Animals↗

PubMed1998

Morphology and surface properties of blends of Eudragit RS with different poly(ethylene glycol)s.

The purpose of this study was to investigate the morphology and surface properties of blends of Eudragit RS, a hydrophobic polymer mainly used for film coating, and poly(ethylene glycol)s (PEG), amphiphilic polymers used as softeners for films. Blends of Eudragit RS and PEGs were prepared as films using the casting technique from methylene chloride. The morphology of those films was evaluated by scanning electron microscopy before and after treatment with water. Sessile drop technique was used to measure solid/liquid contact angles in order to calculate surface free-energy parameters and to investigate phase separation using the Cassie-Baxter approach. Films containing 20, 40, 50, and 60% PEG 3400 and PEG 6000 appeared morphologically unchanged after treatment with water; no phase separation was noticed. Films containing PEG 14,000 after treatment with water showed the presence of a solid emulsion in the range 40, 50, and 60% PEG; a multiple solid emulsion was shown for films containing 60% PEG 20,000. The presence of two-phase systems was shown using contact angle measurements and results were in agreement with microscopic analysis. Calculated surface free-energy parameters indicated that PEG 3400 and 20,000 in a critical concentration of 10% can modify surface parameters of Eudragit RS: for PEG 6000 and 14,000 this critical concentration was found to be between 10 and 20%. The surface polarity of PEG 3400, 6000, and 14,000 was found to be drastically reduced upon addition of 5% Eudragit RS; spontaneous surface layering of Eudragit RS could be reasonably hypothesized for PEG 3400. This study revealed that surface parameters of a polymer can be modified in the presence of a relatively small amount of a second material.

Acrylic Resins↗

PubMed2002

Small angle neutron scattering measurements of synthetic polymer dispersions in matrix-assisted laser desorption/ionization matrixes.

Small angle neutron scattering (SANS) is used to measure the size and the dispersion of synthetic polymers in matrix-assisted laser desorption/ionization (MALDI) matrixes. Deuterated polystyrene (DPS) and dithranol in tetrahydrofuran were deposited by electrospray onto a substrate for small angle neutron scattering (SANS) measurements. DPS with 6050 and 27,000 g mol(-1) molecular masses were prepared at mass fractions between 0.2 and 6%. All samples contained large aggregates of DPS with characteristic sizes >200 A that represent hundreds of aggregated chains. Samples of mass fraction 1% DPS (6050 g mol(-1)) in 2,5-dihydroxybenzoic acid, all-trans-retinoic acid, and sinapinic acid also have large zero angle scattering characteristic of large aggregates. The morphological trend obtained from the SANS measurements of the DPS aggregate size in the four matrixes is dithranol > 2,5-dihydroxybenzoic acid > all-trans-retinoic acid > sinapinic acid. These measurements indicate that DPS in dithranol exhibits the most strong phase separation, while DPS in sinapinic acid shows considerable domain mixing. All of these matrixes produce MALDI signal strength under appropriate conditions, suggesting that strong phase separation does not diminish the signal-to-noise ratio. DPS (188,000 g mol(-1)) in biphenyl was used as a model system of a matrix that can be either crystalline or amorphous. SANS data shows that above the biphenyl melting point, a conventional solution is formed that has molecularly dispersed polymers. Upon crystallization, there is strong aggregation of the DPS into large domains. Therefore, the crystalline matrixes commonly used in MALDI measurements probably cause large aggregations of polymers to be present during the MALDI process.

Journal Article↗

PubMed1987

A differential scanning calorimetry study of the interaction of alpha-tocopherol with mixtures of phospholipids.

When alpha-tocopherol was included in multibilayer vesicles of dimyristoylphosphatidylcholine, dipalmitoylphosphatidylcholine and distearoylphosphatidylcholine it induced a broadening of the main transition and a displacement of this transition to lower temperatures, as seen by differential scanning calorimetry. This effect was quantitatively more important in the samples of distearoylphosphatidylcholine than in those of the other phosphatidylcholines. Alpha-Tocopherol when present in equimolar mixtures of dimyristoylphosphatidylcholine and diastearoylphosphatidylcholine, which show monotectic behaviour, preferentially partitions in the most fluid phase. The effect of alpha-tocopherol on the phase transition of dilauroylphosphatidylethanolamine and dipalmitoylphosphatidylethanolamine is qualitatively different of that observed on phosphatidylcholines, and several peaks are observed in the calorimetric profile, probably indicating the formation of separated phases with different contents in alpha-tocopherol. The effect was more apparent in dipalmitoylphosphatidylethanolamine than in dilauroylphosphatidylethanolamine. The inclusion of alpha-tocopherol in equimolar mixtures of dilauroylphosphatidylethanolamine and dipalmitoylphosphatidylcholine, which show cocrystallization, only produced a broadening of the phase transition and a shift to lower temperatures. However, in the case of equimolar mixtures of dipalmitoylphosphatidylcholine which also show cocrystallization, the effect was to cause lateral phase separation with the formation of different mixtures of phospholipids and alpha-tocopherol. Alpha-Tocopherol was also included in equimolar mixtures of phosphatidylethanolamine and phosphatidylcholine showing monotectic behaviour, and in this case alpha-tocopherol preferentially partitioned in the most fluid phase, independently of whether this was composed mainly of phosphatidylcholine or of phosphatidylethanolamine.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1988

Cell membrane, but not circulating, carcinoembryonic antigen is linked to a phosphatidylinositol-containing hydrophobic domain.

Carcinoembryonic antigen is present in the cell membrane of most tumors of colorectal origin and in the plasma of patients with colorectal cancer and other malignancies. In this paper we demonstrate that carcinoembryonic antigen can be released from HT-29 cells by phosphatidylinositol specific phospholipase C. Triton X-114 phase separation shows that phospholipase C converts the antigen into a water soluble protein. In addition, plasma carcinoembryonic antigen behaves as the cleaved antigen in phase separation experiments. This strongly suggests that carcinoembryonic antigen is attached to cell membranes by a glycosyl-phosphatidylinositol anchor and that it can be released in vivo by enzymatic cleavage of the hydrophobic tail.

Carcinoembryonic Antigen↗

PubMed1987

Role of the physical state of the hepatic microsomal membrane in the formation of bilirubin diglucuronide.

In vitro formation of bilirubin diglucuronide by rat hepatic microsomes proceeds efficiently only under specific conditions; i.e., a low level of bilirubin, temperature greater than 23-24 degrees C and treatment of the microsomes with a very specific level of perturbant (J. Biol. Chem., 258: 15028-15036). In the present study, the effect of temperature and detergents on the anisotropy of fluorescent probes in the rat hepatic microsomal membrane was used to determine the role of the physical state of the membrane in controlling the formation of bilirubin diglucuronide. A lipid phase separation that occurred at 23 +/- 2 degrees C was identified in these membranes indicating that bilirubin diglucuronide is formed efficiently only above the lipid phase separation when the phospholipids are in the liquid crystalline state. In addition, use of fluorescent probes for the surface and core of the membrane indicates that alterations in the physical state of the hydrophobic core rather than the phospholipid polar head group region of the membrane controls the in vitro formation of bilirubin diglucuronide.

Animals↗

PubMedDate not supplied

DNA-cationic surfactant interactions are different for double- and single-stranded DNA.

The stability of DNA in solution and the phase behavior in mixtures with dodecyltrimethylammonium bromide (DTAB) were investigated. By means of circular dichroism, UV absorption, and differential scanning calorimetry, we found that for dilute solutions of DNA with no addition of salt the DNA molecules are in the single-stranded conformation, whereas the addition of a small amount of NaBr, 1 mM, is sufficient to stabilize the DNA double-helix. Furthermore, at higher DNA concentrations, native DNA becomes the most stable structure, which is due to a self-screening effect. By phase diagram determinations of the DNA-surfactant system, we found that the effect of salt on phase behavior mainly relates to a difference in interaction of the amphiphile between single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA). The difference in association between ss and dsDNA with surfactants of different chain lengths can be interpreted in terms of an interplay between hydrophobic and electrostatic interactions, the latter being influenced by polymer flexibility. In this way, a nonmonotonic variation can be rationalized. A crossing of the phase separation lines with DNA concentration can be rationalized in terms of a change in relative stability of ss and dsDNA. The fact that ssDNA phase separates earlier than dsDNA in association with DTAB, may serve as a basis for a method of easily separating dsDNA from ssDNA by the addition of surfactant; this is verified as monitored by circular dichroism measurements.

Calorimetry, Differential Scanning↗

PubMed2006

Magnetically separable phase-transfer catalysts.

Magnetic nanoparticles-supported quaternary ammonium and phosphonium salts were prepared and evaluated as phase-transfer catalysts. Some of them exhibited good activities that were comparable to that of tetra-n-butylammonium iodide. The catalysts were readily separated using an external magnet and reusable without significant loss of their catalytic efficiency.

Journal Article↗

PubMed2005

Modeling the morphology and mechanical properties of sheared ternary mixtures.

Through a combination of simulation techniques, we determine both the structural evolution and mechanical properties of blends formed from immiscible ternary mixtures. In this approach, we first use the lattice Boltzmann method to simulate the phase separation dynamics of A/B/C fluid mixtures for varying compositions within the spinodal region. We also investigate the effect of an imposed shear on the phase ordering of the mixture. We assume that the fluid is quenched sufficiently rapidly that the phase-separated structure is preserved in the resultant solid. Then, the output from our morphological studies serves as the input to the lattice spring model, which is used to simulate the elastic response of solids to an applied deformation. These simulations reveal how the local stress and strain fields and the global Young's modulus depend on the composition of the blend and the stiffness of the components. By comparing the results for the sheared and unsheared cases, we can isolate optimal processing conditions for enhancing the mechanical performance of the blends. Overall, the findings provide fundamental insight into the relationship between structure, processing, and properties for heterogeneous materials and can yield guidelines for formulating blends with the desired macroscopic mechanical behavior.

Journal Article↗