Phase separating mixtures

Phase domain in a phase-separated mixture that is surrounded by a continuous phase but isolated from all other similar phase domains within the mixture. 

These observations are analogous to those of phase-separating mixtures by spinodal decomposition mechanism, leading several researchers to invoke the idea that the early stage of polymer crystallization is spinodal decomposition. 

If any of these features is not observed in the early stages of crystallization, the spinodal decomposition mechanism commonly encountered in phase-separating mixtures cannot be associated with polymer crystallization. 

Restarting of a phase-separated mixture (failed emulsion) is similar to restarting an emulsion, but the starting pressure surge is substantially greater as a result of total separation of phases. 

Emulsion (30% water) Emulsion (38% water) Phase-separated mixture (30%)... 

Fig. 38. Schematic plots of the free energy barrier for (a) the mean field critical region, i.e. / 1, and (b) the non-mean field critical region, i.e. R,l( 1 -/ /7 ) 4— V2 i. When AF /Tc is of order unity, a gradual transition from nucleation to spinodal decomposition (in a phase-separating mixture) or spinodal ordering" (in a system undergoing an order-disorder transition with non-conserved order parameter distinct from tj>) occurs. From Binder (1984b).

In contrast, lyotropic LCs (LLCs) are molecules that form ordered fluid phases that are phase-separated mixtures in which the degree of order depends on the proportion of LC mesogen relative to an added immiscible solvent such as water [3,4], In addition to morphology dependence on system composition, LLC phases are also sensitive to other external parameters... 

Gongwen Peng, Feng Qiu, Valeriy V. Ginzburg, David Jasnow and Anna C. Balazs, Forming supramolecular networks from nanoscale rods in binary, phase-separating mixtures. Science, 288 (2000), 1802-1804. 

The phase diagram in Fig. 15 is a prediction of thermodynamic equilibrium however, the process path of a sample intuitively affects the observed phase. For example, if end-functionalized polymers are miscible in the melt, then microphase separation could occur upon cooling. However, if macroscopic phase separation occurs first, then pseudo block copolymers can only form at the interface of a phase-separated mixture, further blocking the molecular transport required for structure formation. If both free and dimerized homopolymer are present during phase separation or microphase segregation, then the length scale of phase segregation/... 

Phase-separated mixtures are obtained when one tries to mix most polymers. But strangely enough, the phase-separated materials often turn out to be rather useful. They are called immiscible blends. 

For the immiscible blended polymer type, phase-separated mixtures are obtained when one tries to mix most polymers. However, strangely enough, the phase-separated materials also turn out to be sometimes useful. The examples of immiscible polymer are polystyrene and polybutadiene. When polystyrene is mixed with a small amount of polybutadiene, the two polymers do not blend. Polybutadiene separates from the polystyrene into Uttle spherical blobs. 

Furthermore, De Vries et al. reported a simple method to place target molecules specifically at two diametrically opposed positions in the molecular coating of MNPs [20,21]. This approach is based on functionalization of the polar singularities that must form when a curved surface is coated with ordered monolayers, such as a phase-separated mixture of ligands. The molecules placed at these polar defects were used as chemical handles to form ID AuNP chains. 

Piculell and Lindman [29] recently discussed the phase separation of aqueous mixtures of polymer/polymer and polymer/surfactant solutions in terms of association and segregation. When one of the phases is concentrated with both of the components, the phase separation is termed associative, and when the separating phases contain components of comparable total concentrations it is called a segregative phase separation. Mixtures of nonionic polymer and ionic surfactant mainly show an associative phase separation. However, this may be due to the fact that most studies performed in the chemical literature have been specifically concerned with systems where P—S association has been important. Systematic experiments on P—S systems where both are negatively charged are reported to show a segregative phase separation. 

When a diblock copolymer AB is added to a phase-separated mixture of homopolymers A and B, one of the following three events is likely to occur. 

Formation of surfactant coated starch nanopartides The loading of surfactant stabilized reverse micelles with starch nanospheres was studied. The surfactant-solvent systems used were AOT (sodium di-2-ethylhexylsulfosuccinate)/isooctane, CTAB (cetyl trimethyl ammonium bromideVchloroform and TritonX-100 (polyoxyethylene(10) isooctylphenylether)/toluene. These surfactants were selected due to their use by others for the solubilization of enzymes in reversed micelles(26-28). To load the reverse micelles, a concentrated (0.2Sg/mL) aqueous solution of starch nanospheres was added to the different surfactant/solvent pairs. The percent incorporation of starch in the nanospheres was determined based on the amount of the starch nanopartides that could be added to the surfactant/solvent system prior to the formation of a cloudy phase separated mixture. 

Glotzer, S.C., DiMarzio, E.A., and Muthukumar, M. (1995) Reaction-controlled morphology of phase-separating mixtures. Phys. Rev. Lett., 74, 2034-2037. 

Even in a phase separated mixture, each phase will contain a proportion of both components. Where the majority component of one of the phases is crystallizable, crystallization can occur rapidly in that phase, but extend into the phase where it is the minority component. This can be observed in blends of polypropylene with... 

Lipatov et al. used a cobalt gun to irradiate phase-separated mixtures of cholesteric liquid crystal microdomains dispersed in a polyurethane matrix, etc. 

In the first category, polystyrene (PS) and poly(vinyl methyl ether) (PVME) have been reported to be compatible when films are cast from suitable solvents.5 But phase separation can be induced in a compatible film simply by heating the mixture to about 150°C. Subsequent slow cooling of the phase-separated mixture resTilts in a compatible film. The thermally induced phase separation behavior of PS-PVME mixture indicates the existence of LOST. The presence of UCST was not reported, althoTigh, according to Patterson s theory, if LOST exists, UCST should also exist. 

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