Additives, homogenization mixing with polymers

In the preparation of adhesive patches by direct milling on a two-roll mill, the drug and the bioadhesive are homogeneously mixed with or without the aid of a solvent. The polymer/drug mixture may then be compressed to its desired thiekness and patches of appropriate size may be cut or punched out. The polymer/drug mixture prepared with a solvent may require an additional drying step by air or in an oven. 

To form cholesteric liquid crystalline polymers, one either polymerizes cholesteric monomers or mixes low molecular mass cholesteric liquid crystals with polymers. In the latter case, two components may be mixed homogeneously or in such a way that the polymers act as a matrix while the small molecular mass cholesteric liquid crystals are in droplets, known as the polymer-dispersed liquid crystals (PDLC) (Doane et al., 1988) or the nematic curvilinear aligned phase (NCAP) (Fergason, 1985). In addition, there are many polymers in nature exhibiting the cholesteric phase such as PBLG, cellulose, DNA, etc. 

The involvement of pre-synthesized metal NPs in the formation of CP-based nanocomposites offers the possibility to incorporate metallic species with defined characteristics, e.g. size and stabilization shell, in the polymer material. An additional important advantage is the opportunity to achieve a homogeneous distribution of the metal particles in three dimensions that is usually not the case for metal deposition in pre-synthesized supported CPs. The synthesis of nanocomposites by means of pre-synthesized metal NPs [46-87] has been approached in several ways by carrying out electrochemical [46—59,70,71] or chemical [60-69] polymerization in their presence by simple mixing with dissolved CPs [73—76] by NPs adsorption on pre-synthesized CP layers [77-83] by layer-by-layer (LbL) adsorption using dissolved CPs [84—87] (Table 7.2, A and B). 

Okumus et al. (1994) developed a mixed-matrix polymer-zeolite memljrane for PV. In the preparation of these manbranes, cellulose acetate (CA) as base polymer, AC, or DMF as solvent, and 13X or 4A zeolites as fillers were used. It was observed that the addition of zeolite to the membrane matrix improved the flux value twofold with respect to its homogeneous manbranes with some loss in their selectivity. For example, for a feed concentration of 74% EtOH at SO C and 1 mmHg, the flux value for the unfilled membrane was 0.6 1/m h, and for a 30% zeolite-filled man-brane, the flux was increased to 1.33. For these cases, the selectivities were 7.76 and 5.0 for the unfilled and filled membranes, respectively. 

Further addition of surfactant results in each polymer hydrophobe associating with its own surfactant micelle and the solution viscosity diminishing as the cross-linking breaks down (Fig. 28d). Two-phase systems may or may not return to homogeneous mix-... 

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