Polymer types using sodium salts

The phase behavior of the polymers is also dependent on the type and concentration of salt present. Many times a sufficiently high concentration of salt in a single polymer solution can induce phase separation to form one salt-rich and one polymer-rich phase. Sodium and potassium phosphate are commonly used salts. 

Metal/polymer nanocomposites were prepared by Chen and co-workers (55) using dispersion of metal chlorides in polyurethane. Both pol5nirethane and metal salts were dissolved in iV,A( -dimethylacetamide, followed by film casting and reduction of the metal salts by sodium borohydrate. The metal particle size depended on the type of metal salt used and on its concentration. 

Herrero and Acosta (80) investigated the microstmcture of poly(ethylene oxide)-poly[(octafluoropentoxy)(trifluoroethoxy)phosphazene] blends. Limited miscibility of both components was inferred, based on the observed shift of the components glass-transition temperatures. Wycisk and co-workers (81) prepared membranes from blends of sulfonated poly[bis(3-methylphenoxy)phosphazene] with polyimides, polyacrylonitrile, and Kynar FLEX PVDF. Morphology, electrochemical performance, and methanol permeabilities of the membranes were then evaluated as part of a program to investigate such blends in direct methanol fuel cells. The polymers were immiscible and a domain-type structure was observed. The best compatibility resulted when the tetrabutylammonium or sodium salt of the polyphosphazene was used (82). 

Two types of stabilizers are used, one of which is basically the type of water-soluble polymers (often in the presence of an electrolyte or a buffer) and the other is a type of water-insoluble inorganic compounds. The former type includes polyvinyl alcohol (PVA), hydroxypropyl cellulose, sodium poly(styrene sulfonate), and sodium salt of acrylic acid-acrylate ester copolymer. The latter type includes magnesium silicate hydroxide (TALC), hydroxyapatite, barium sulfate, kaolin, magnesium carbonate and hydroxide. 

Generally speaking, hydrophilic pol5miers indicate those made of linear poljmiers with hydrophilic side chains or hydrophilic main chains. As shown in Table 1, there are natural and synthetic polymers. They are nonionic-, anionic-, cationic-, and betaine-type polymers. Depending on the type of polymer adopted, the water absorption characteristics differ greatly. The number of polymers actually produced and used is highly limited. In terms of production, alkali metal salt-crosslinked poly(acrylic acid) (sodium salt-crosslinked poly(acrylic acid)) dominates world production. 

As discussed previously in the section on primary batteries, an acrylate is often used as a crosslinkable monomer to form a polymer matrix for a nonaqueous electrolyte. The salt-in-polymer type polymer electrolyte made by dissolving trifluoroethylene glycol methacrylate into methoxy poly(ethylene glycol methacrylate) forms a comb-like network structure at the covalently bonded portion. The ethylene oxide chain consists of 22 monomer units, and the ionic conductivity at room temperature is reported to be 10 S/cm. If sodium thiocyanate is used [30] instead of lithium trifluoromethane sulfonate, the ionic conductivity reduced to 10 S/cm. However, by adding 50 wt% of PC as a plasticizer, the ionic conductivity reaches 10 " S/cm. 

Polyion complexes between acid derivatised polythio-phene (poly(thiophene-3-acetic acid)), PTAA (Figure 14.39), and a stable surface active cation have been used to construct conductive LB films. In this case, the formation of a polyion complex renders PTAA surface active and provides additional control over the molecular orientation of the polymer within the monolayer. The monolayer assembly thus obtained has a structure composed of a well ordered condensed monolayer of the surface active molecule onto which is a single monolayer of PTAA ionically bound. For example, the sodium salt of PTAA can be readily absorbed onto a monolayer of dimethyldioctadecylam-monium bromide. The monolayer assembly of the polyion complex was successfully transferred into LB film in a Z-type manner [294]. 

Latex Types. Latexes are differentiated both by the nature of the coUoidal system and by the type of polymer present. Nearly aU of the coUoidal systems are similar to those used in the manufacture of dry types. That is, they are anionic and contain either a sodium or potassium salt of a rosin acid or derivative. In addition, they may also contain a strong acid soap to provide additional stabUity. Those having polymer soUds around 60% contain a very finely tuned soap system to avoid excessive emulsion viscosity during polymeri2ation (162—164). Du Pont also offers a carboxylated nonionic latex stabili2ed with poly(vinyl alcohol). This latex type is especiaUy resistant to flocculation by electrolytes, heat, and mechanical shear, surviving conditions which would easUy flocculate ionic latexes. The differences between anionic and nonionic latexes are outlined in Table 11. 

Examples of the Michael-type addition of carbanions, derived from activated methylene compounds, with electron-deficient alkenes under phase-transfer catalytic conditions have been reported [e.g. 1-17] (Table 6.16). Although the basic conditions are normally provided by sodium hydroxide or potassium carbonate, fluoride and cyanide salts have also been used [e.g. 1, 12-14]. Soliddiquid two-phase systems, with or without added organic solvent [e.g. 15-18] and polymer-supported catalysts [11] have been employed, as well as normal liquiddiquid conditions. The micellar ammonium catalysts have also been used, e.g. for the condensation of p-dicarbonyl compounds with but-3-en-2-one [19], and they are reported to be superior to tetra-n-butylammonium bromide at low base concentrations. 

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