Phenyl substituted polyphenylene

Billow and Miller [187] also reported fairly similar results for poly(phenylene)s prepared from mixtures of terphenyls. Poly(m-phenylene) [188], phenyl-substituted polyphenylene [189] and perfluoropolyphenylene [190] have thermal and oxidative stabilities similar to that of poly(p-phenylene). Polyphenylenes synthesized by Wurtz-Fittig and Ullmann reactions were reported to withstand heating up to 500°-550°C [187,191,192]. Electrically conductive azo derivatives of polyphenylene (cTo= l-40ohm cm ) were stable up to 300°C without any noticeable decomposition, whereas the conductive block co-polymer of poly-phenylene with p-diethynylbenezene could withstand heating for many hours at 400°-450°C [I], Poly(p-phenylene) as well as poly(tetrafluoroethylene) have been reported to withstand a similar temperature without any thermal degradation and may be used safely up to similar... 

This information is obtained from a single sample by high resolution oligomer GPC coupled with a diode array detector. As shown in figure 1 the absorption maximum of phenyl substituted polyphenylene vinylene is approached at a polymerization degree 7-8. 

Methyl substituted polyphenylene has a limited thennal stability. The phenyl substituted polyphenylene is soluble in chloroform, anisol and toluene (26). DSC shows a step at 180 °C. The melting point of 280 °C is observable only during the first heating. The material solidifies to an anisotropic glass from anisotropic melt... 

An established technique for preparing soluble derivatives of intractable polymers is to add solubilizing substituents to the monomer. Thus, insoluble polyphenylenes have been rendered soluble (75) in common solvents such as chloroform by phenyl substitution. Similarly, a wide range of substituted pyrroles and thiophenes have been investigated to improve the tractability of these relatively stable conducting polymers. The chemical and electropolymerization of N-substituted pyrroles (76) gave polymers with substantially decreased conductivities, generally by a fector of 10 compared to polypyrrole. However, monomers substituted at the 3 and 4 positions of... 

In the search for the gas separation membrane materials of improved permeability and selectivity, various chemical modifications of PPO have been investigated - e.g. carboxylation [4, 5], fluorination [6], nitration [7] bromination [8-10] and sulfonation [11]. In this chapter though we shall focus on the investigations of gas transport through the membranes of unmodified 2,6-substituted polyphenylene ethers - both homo- and copolymers - with the repeat unit represented by the formula (1). In this formula, R stands for methyl, phenyl or allyl group. 

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