POLYANHYDRIDES - XI - POLY(ESTER-ANHYDRIDE)S DERIVED FROM 4-HYDROXYBENZOIC ACID, VANILLIC ACID, AND ALIPHATIC DICARBOXYLIC-ACIDS

Poly(ester-anhydride)s, PEA's, built up by 50 mol% ester and 50 mol% a nhydride groups were prepared by polycondensation of 0,0'-bistrimethyl silyl 4-hydroxybenzoic acid and various alpha,omega-alkane-dicarbonylc hlorides. The polycondensations were conducted either in bulk or in 1- chloronaphthalene. High yields (up to 94%) were obtained under both re action conditions, but the higher inherent viscosities resulted from p olycondensations in 1-chloronaphthalene. IR-and C-13 NMR spectroscopy revealed that reaction temperatures above 200 degrees C cause side rea ctions such as transacylation and transesterification. Analogous serie s of polycondensations were conducted with 0,0'-bistrimethylsilyl vani llic acid. The resulting PEA's were amorphous, whereas the PEA's deriv ed from 4-hydroxybenzoic acid are semicrystalline.