A series of aliphatic polybenzoxazoles of high molecular weights was prepared in three steps by the low-temperature solution polycondensation of tetrakis(trimethylsily1)-substituted 4,4'diamino-3,3'-dihydroxybiphenyl with aliphatic diacid chlorides with 7 to 12 methylene units yielding trimethylsilyl-substituted poly(o-hydroxyamide) precursor polymers, which were subjected to desilylation with methanol giving the poly(o-hydroxyamide)s, followed by thermal cyclodehydration. The aliphatic polybenzoxazoles had melting points in the 172 to 246OC range with glass transition temperatures of 55-97OC. They were stable in the melt state up to 40O0C in nitrogen. These polybenzoxazoles and the corresponding bisbenzoxazole model compounds exhibited no liquid cryst allinit y .
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