Heterocyclic polyarylenes

There are only a few communications in the literature on the fabrication of fibers from LC polymers of a different chemical structure than aromatic polyamides and heterocyclic polyarylenes of the type of PBT or PBO, and they primarily concern aromatic polyhydrazides. These polymers can be considered polyamides prepared with hydrazine as the diamine. LC solutions of polyhydrazides based on terephthalic and oxalic acids have been prepared in both aqueous solutions of organic bases (secondary amines or quaternary ammonium bases) and in concentrated sulfuric acid [57]. In sulfuric acid, polyhydrazides are unstable and undergo hydrolytic decomposition, but the copolyhydrazide based on oxalic, chloro-, and terephthalic acids form relatively stable LC solutions in sulfuric acid... 

The first heterocycle-based systems that had some relevance in the development of new types of fuelcell membranes were sulfonated polyarylenes ° and... 

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