High-temperature polymer polybenzoxazole

Studies of uniaxial extension on noncrystallizable elastomer, poly(phenyl methyl siloxane) showed results which are consistent and comparable with those obtained for PDMS, suggesting that the crystallization is not important for this type of reinforcement [20]. Other examples for reinforcement effects achieved with the addition of silica fillers include polyisobutylene [24], poly(ethyl acrylate) [3], poly (tetra methylene oxide) [29,30], and some high-temperature polymers such as aromatic polyamides [14,33,34], polyi-mides [15,38,39], polybenzoxazoles [16,17], and polyben-zobisthiazoles [16,17]. Results indicated that the modulus increases with increase in silica content while the tensile... 

Both negative and positive tone aqueous developable materials have been introduced. Negative tone materials have been derived from tbe covalent-type polyamic ester precursors through the use of additives that enhance solubility of the unexposed film in aqueous developers (53). Positive tone materials are based on either polyamic ester precursors containing carboxylic acid (54) or phenolic oxygen substituents (55,56) or on aromatic poly(ortho-hydroxyamides) as precursors to polybenzoxazoles (57,58), a class of high temperature stable, heterocyclic polymers with thermal and mechanical film properties similar to polyimides (Fig. 18). In both approaches, the acid-base reaction of the phenolic or carboxylic... 

Successful construction of textile fabrics as substrates for the integration of solar cells has to take into account the type and grade of polymer used, the type of fibre extruded from it, and subsequent fabric construction. Fibre selection is very much determined by its ability to withstand successfully the elevated temperatures required for the deposition of the thin layers comprising a solar cell. Where these temperatures are as high as 400 °C or more, as in the deposition of many types of solar cell, selection is restricted to high-performance fibres, such as glass fibres, polyimides, polybenzimidazoles and polybenzoxazoles, but these types of fibre are expensive. However, it has been demonstrated that nanocrystalline silicon films can be successfully laid down at temperatures as low as 200 °C [4, 5], a factor that then broadens fibre choice to include a range of commodity fibres. 

In this paper we report the synthesis of new AB monomers which have potential for forming polybenzoxazoles with backbone alkane and alkene moities. Application to monomers of the previously developed low-temperature, high-yield condensation procedure (8) employing triphenylphosphine, hexachloroethane and pyridine is described. The soluble aryl-alkyl and aryl-alkenyl polyamides thus obtained were characterized and converted to polybenzoxazoles. Comparisons are presented between polymers obtained by this two-step method and those prepared by traditional methods. 

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