Polymers phase separation

Phase-separated polymers, 215 Phase separation, 217-222 Phase transfer catalysts, 288, 563-564 Phase-transfer-catalyzed alkaline hydrolysis of nylon-4,6, 570 of nylon-6,6, 569-570 PHB. See Poly(3-hydroxybutanoic acid) (PHB)... 

Micro-composites are formed when the polymer chain is unable to intercalate into the silicate layer and therefore phase separated polymer/clay composites are formed. Their properties remain the same as the conventional micro-composites as shown in Figure 2(a). Intercalated nano-composite is obtained when the polymer chain is inserted between clay layers such that the interlayer spacing is expanded, but the layers still bear a well-defined spatial relationship to each other as shown in Figure 2(b). Exfoliated nano-composites are formed when the layers of the day have been completely separated and the individual layers are distributed throughout the organic matrix as shown in Figure 2(c). 

This document is organized into three sections. The first defines terms basic to the description of polymer mixtures. The second defines terms commonly encountered in descriptions of phase-domain behaviour of polymer mixtures. The third defines terms commonly encountered in the descriptions of the morphologies of phase-separated polymer mixtures. 

Particle nuclei Precipitate including no Phase-separated polymer containing... 

Fig. 37. Theoretical predictions for thin film morphology of a phase-separating polymer mixture. Case I yA where yA and yB are the surface tensions of components A and B, respectively, and yAB is the interfacial tension. Case II yA

Two effects attributed to long-chain molecules cause features of the coarsening processes taking place in phase-separating polymer systems ... 

Network Structure of Micrometre-Scale Cavity Obtained from Phase-Separated Polymer Blends as Characterised by Using... 

NETWORK STRUCTURE OF MICROMETRE-SCALE CAVITY OBTAINED FROM PHASE-SEPARATED POLYMER BLENDS AS CHARACTERISED BY USING PROBE MOLECULES... 

The most popular way to synthesize microgel particles is via emulsion polymerization. Each micelle acts as a separate microreactor, preventing macrogelation during the reaction. Another way to obtain microgel particles is the irradiation of phase-separated polymer solutions (Fig. 5). Phase separation can be achieved by heating (for temperature-sensitive polymers) or mixing with non-solvents. 

Young, T-H., Lin, D.-J., Gau, J.-J., Chuang, W.-Y., and Cheng, L.-P. (1999), Morphology of crystalline Nylon-610 membranes prepared by the immersion-precipitation process Competition between crystallization and liquid-liquid phase separation, Polymer, 40, 5011-5021. 

Consider a phase-separated polymer solution, where one phase is rich in polymer while the other is poor in this component (Figure 11-18). JThings never phase-separate into their pure components even in grossly phase-separated systems, like oil and water, there is always a little bit of one in the other]. 

Phase separated polymer mixtures are important in many practical applications, such as confectionery and low-fat foods. Values of the fraction (x) of a component can be replaced by those of the fraction of solvent (Sx) associated with polymer (Morris, 1998) so that Figure 6-22 may be used also to understand the role of solvent partitioning. A key assumption is that there is complete separation of the two polymers in to their respective phases, so that the relative phase volumes (hence, the polymer concentration in each phase) may be characterized by the p-factor, defined as ... 

The main purpose of this paper is to demonstrate the striking similarity between the behavior of particulate filled polymers and phase separated polymers. The changes in mechanical proper-... 

Phase-separated polymers are of practical importance. An example is the way that a brittle polymer such as polystyrene may be toughened by the addition of an incompatible rubber that undergoes phase separation. Provided that this is done with attention to the interface between the two phases, a rubber-toughened high-impact polystyrene (HIPS) will result. 

The definition of compatibility has been differentiated from miscibility since it is concerned with phase-separated polymers and is approached through the attainment of optimum properties for the blend (Bonner and Hope, 1993). Two of the main technologies used to achieve it are the addition of a third component (as discussed above) and reactive blending. The target in using a compatibilizer is the control of the interfacial tension between the components in the melt, translating to interfacial adhesion in the blend after processing. 

TABLE 3 Range of diameter of soluble complexes as determined by quasi-elastic light scattering upon variation of pH from pHc (incipient association) to pH (phase separation). Polymer acronyms see the title of Table 1. (Reprinted with permission from Ref. 15. Copyright 1993 American Chemical Society.)... 

Of all the characterization methods employed to study the morphologies of polymerized vesicles, cryo TEM is perhaps the most powerful. SEM, freeze fracture TEM, QLS, and probe diffusion studies alone cannot adequately distinguish between the polymer morphologies that have been proven to occur such as between hollow polymer shells and phase separated polymer-vesicle systems. 

Figures la and Ic show the structure of the phase-separated polymer blend films obtained by dip coating from a PS-COOH/PMMA (30 70 weight ratio) solution. The morphology of the as-deposited films of two different (15 and 30 nm) thicknesses agreed well with their PS content of 30%. Indeed, the minor PS phase was dispersed in the major PMMA phase. However, after the anneahng and extraction of PMMA, the grafted PS layer demonstrated a rather different type of surface structures for the PS-COOH /PMMA films of different...

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