CHEMISTRY AND PROPERTIES OF POLY(ARYLENE ETHER BENZOXAZOLE)S

Novel poly(arylene ether benzoxazole)s were prepared by the aromatic nucleophilic displacement reaction of two new bis(hydroxyphenyl benzoxazole)s with activated aromatic difluorides. The bis(hydroxyphenyl benzoxazole)s were prepared from either 3,3'-dihydroxy-4,4'-diaminobiphenyl or 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane and phenyl-4-hydroxybenzoate. The polymerizations were carried out in either N,N-dimethylacetamide or diphenylsulphone, depending on the bis(hydroxyphenyl benzoxazole). The polymers had glass transition temperatures ranging from 204 to 275-degrees-C and inherent viscosities from 0.25 to 1.04 dl g-1. Several of the polymers prepared from the 3,3'-dihydroxy-4,4'-diaminobiphenyl-derived bis(hydroxyphenyl benzoxazole) were semi-crystalline. Thermogravimetric analysis showed a 5% weight loss occurring at almost-equal-to 450-500-degrees-C in air and almost-equal-to 475-530-degrees-C in nitrogen. Thin films of the hexafluoroisopropylidene-containing polymers exhibited 23-degrees-C tensile strengths and moduli of 83-103 MPa and 1.9-2.4 GPa respectively, and high elongations. The chemistry and the physical and mechanical properties of these polymers are discussed.