Poly salts

The melt behavior of sulfonated polystyrene ionomers was studied by Lundberg and coworkers41. As was shown in the case of a sulfonated elastomer30, sulfonation of polystyrene leads to an increase in the melt viscosity (measured at 250 °C) of the SPS upon neutralization, indicating increased association of the sodium poly-(salt). A sudden jump of the melt viscosity occurs at the point of complete neutralization, where a critical concentration of Na polystyrenesulfonate is reached, apparently resulting in a sharp phase separation between the ionic and hydrophobic domains (Figure 5). 

Ihe quest for interactive or bioactive dental restorative materials is not a totally new endeavor in dental materials. For example, as a general concept, glass ionomer cements (GICs) have been endorsed as a bioactive material because of their dynamic release of fluoride, as well as their unique mineral-based poly-salt matrix composition that is claimed to also contribute to the ability to remineralize calcium-depleted tooth structure. The continuous release of fluoride by GICs and resin-modified glass ionomers (RMGIs) has also been positioned as a potential mechanism to delay or inhibit secondary caries at teeth restored with these materials at the margins of the restorations [47,48]. 

The simplest method to use is reversible salt formation polarimetric and spectropolari-metric studies of salts of optically inactive polyacids (such as polyacrylic, polyitaconic or poly-p-vinylbenzoic acids) with OA bases (like quinine or nicotine) as well as optically inactive bases (polyvinylpyridines) with OA acids (tartaric, mandelic, t/-camphor-/3-sulfonic or with L-menthylbromoacetate) have been reported by Schulz et al f 176, 177]. They found that the optical activity of the poly-salts affected by the microconfiguration of the polymer chain are quite different from the corresponding salts of OA low-molecular weight compounds the ORD curves of isotactic and atactic poly-2-vinylpyridine salts with D-tar-taric acid were found to be anomalous, with a higher value of rotation for the isotactic polymeric salt but in the case of methacryloylnicotine salts it seems that the observed differences can be explained by the assumption of increased specific rotation of the associated nicotine cations in the polymeric salt [178] and not by a conformational effect. 

When 4-vinyl jyridine was reacted with poly (st5rrene sulfonic add) 82), poly (vinyl sulfonic add) 83) or poly(methacrylic add) 83) insoluble, poly(salts) consisting of stoichiometric quantities of vinyl pyridine and the poly(acid) were obtained. The a regate obtained when solutions of poly(methacrylic add) and poly(vinyl pyridine were mixed had an infrared spectum almost identical with that obtained by reaction of 4-vinyl pyridine with poly(methacrylic acid). Further, when the last-... 

The reports were that water condensed from the vapor phase into 10-100-/im quartz or pyrex capillaries had physical properties distinctly different from those of bulk liquid water. Confirmations came from a variety of laboratories around the world (see the August 1971 issue of Journal of Colloid Interface Science), and it was proposed that a new phase of water had been found many called this water polywater rather than the original Deijaguin term, anomalous water. There were confirming theoretical calculations (see Refs. 121, 122) Eventually, however, it was determined that the micro-amoimts of water that could be isolated from small capillaries was always contaminated by salts and other impurities leached from the walls. The nonexistence of anomalous or poly water as a new, pure phase of water was acknowledged in 1974 by Deijaguin and co-workers [123]. There is a mass of fascinating anecdotal history omitted here for lack of space but told very well by Frank [124]. 

When dealing with esters of water-soluble, non steam-volatile, poly-hydric alcohols e.g., ethylene glycol or glycerol), the distillate consists of water only (density 1 00). The water soluble, non-volatile alcohol may be isolated by evaporation of the alkahne solution to a thick syrup on a water bath and extraction of the polyhydric alcohol from the salt with cold ethyl alcohol. 

Dichromated Resists. The first compositions widely used as photoresists combine a photosensitive dichromate salt (usually ammonium dichromate) with a water-soluble polymer of biologic origin such as gelatin, egg albumin (proteins), or gum arabic (a starch). Later, synthetic polymers such as poly(vinyl alcohol) also were used (11,12). Irradiation with uv light (X in the range of 360—380 nm using, for example, a carbon arc lamp) leads to photoinitiated oxidation of the polymer and reduction of dichromate to Ct(III). The photoinduced chemistry renders exposed areas insoluble in aqueous developing solutions. The photochemical mechanism of dichromate sensitization of PVA (summarized in Fig. 3) has been studied in detail (13). 

Two inorganic water-soluble polymers, both polyelectrolytes in their sodium salt forms, have been known for some time poly(phosphoric acid) (12) and poly(siHcic acid) (13). A more exciting inorganic water-soluble polymer with nonionic... 

Under conditions of extreme acidity or alkalinity, acryhc ester polymers can be made to hydroly2e to poly(acryhc acid) or an acid salt and the corresponding alcohol. However, acryhc polymers and copolymers have a greater resistance to both acidic and alkaline hydrolysis than competitive poly(vinyl acetate) and vinyl acetate copolymers. Even poly(methyl acrylate), the most readily hydroly2ed polymer of the series, is more resistant to alkah than poly(vinyl acetate) (57). Butyl acrylate copolymers are more hydrolytically stable than ethyl acrylate copolymers (58). 

Suitable protective coUoids for the preparation of acryhc suspension polymers include ceUulose derivatives, polyacrylate salts, starch, poly(vinyl alcohol), gelatin, talc, clay, and clay derivatives (95). These materials are added to prevent the monomer droplets from coalescing during polymerisation (110). Thickeners such as glycerol, glycols, polyglycols, and inorganic salts ate also often added to improve the quahty of acryhc suspension polymers (95). 

Halex rates can also be increased by phase-transfer catalysts (PTC) with widely varying stmctures quaternary ammonium salts (51—53) 18-crown-6-ether (54) pytidinium salts (55) quaternary phosphonium salts (56) and poly(ethylene glycol)s (57). Catalytic quantities of cesium duoride also enhance Halex reactions (58). 

Sintering has been used to produce a porous polytetrafluoroethylene (16). Cellulose sponges are the most familiar cellular polymers produced by the leaching process (123). Sodium sulfate crystals are dispersed in the viscose symp and subsequently leached out. Polyethylene (124) or poly(vinyl chloride) can also be produced in cellular form by the leaching process. The artificial leather-tike materials used for shoe uppers are rendered porous by extraction of salts (125) or by designing the polymers in such a way that they precipitate as a gel with many holes (126). 

Membranes and Osmosis. Membranes based on PEI can be used for the dehydration of organic solvents such as 2-propanol, methyl ethyl ketone, and toluene (451), and for concentrating seawater (452—454). On exposure to ultrasound waves, aqueous PEI salt solutions and brominated poly(2,6-dimethylphenylene oxide) form stable emulsions from which it is possible to cast membranes in which submicrometer capsules of the salt solution ate embedded (455). The rate of release of the salt solution can be altered by surface—active substances. In membranes, PEI can act as a proton source in the generation of a photocurrent (456). The formation of a PEI coating on ion-exchange membranes modifies the transport properties and results in permanent selectivity of the membrane (457). The electrochemical testing of salts (458) is another possible appHcation of PEI. 

Alkoxide-Type Initiators. Using the guide that an appropriate initiator should have approximately the same stmcture and reactivity as the propagating anionic species (see Table 1), alkoxide, thioalkoxide, carboxylate, and sUanolate salts would be expected to be usehil initiators for the anionic polymeri2ation of epoxides, thikanes, lactones, and sUoxanes, respectively (106—108). Thus low molecular weight poly(ethylene oxide) can be prepared... 

In addition to providing fully alkyl/aryl-substituted polyphosphasenes, the versatility of the process in Figure 2 has allowed the preparation of various functionalized polymers and copolymers. Thus the monomer (10) can be derivatized via deprotonation—substitution, when a P-methyl (or P—CH2—) group is present, to provide new phosphoranimines some of which, in turn, serve as precursors to new polymers (64). In the same vein, polymers containing a P—CH group, for example, poly(methylphenylphosphazene), can also be derivatized by deprotonation—substitution reactions without chain scission. This has produced a number of functionalized polymers (64,71—73), including water-soluble carboxylate salts (11), as well as graft copolymers with styrene (74) and with dimethylsiloxane (12) (75). 

Applications. Polymers with small alkyl substituents, particularly (13), are ideal candidates for elastomer formulation because of quite low temperature flexibiUty, hydrolytic and chemical stabiUty, and high temperature stabiUty. The abiUty to readily incorporate other substituents (ia addition to methyl), particularly vinyl groups, should provide for conventional cure sites. In light of the biocompatibiUty of polysdoxanes and P—O- and P—N-substituted polyphosphazenes, poly(alkyl/arylphosphazenes) are also likely to be biocompatible polymers. Therefore, biomedical appHcations can also be envisaged for (3). A third potential appHcation is ia the area of soHd-state batteries. The first steps toward ionic conductivity have been observed with polymers (13) and (15) using lithium and silver salts (78). 

Table 3. Properties of Poly(ethylene-co-acrylic acid) Salts ...

A number of cationic muds have been developed and used. These ate formulated around quaternary amines or positively charged polymers (108,109). The polymer in some iastances may be a cationic polyacrylamide. Poly(dimethylarnine-fi9-epichloiohydrin) is another material that has been used successfiiUy for drilling shale formations (110,111). Some of these additives may requite a salt such as sodium or potassium chloride for best results. 

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