Nonstoichiometric polycondensation of 4-acetoxybenzoic acid in the presence of monoacetate

Nonstoichiometric polycondensation of 4-acetoxybenzoic acid (ABA) was examined in the presence of three kinds of aromatic monoacetates: 4-hexyloxyphenyl acetate, 4-decyloxyphenyl acetate, and 4-octadecyloxyphenyl acetate. Polymerizations were carried out in liquid paraffin at 320 degrees C under nonstoichiometric conditions, in which the acetoxy group was in large excess of the carboxyl group. Poly(4-oxybenzoyl) (POB) was obtained as crystal at the molar ratio of monoacetates in feed (chi) of less than 80 mol%, meaning that the concentration of the acetoxy group was five times that of the carboxylic group. The obtained POB possessed much higher number average degree of polymerization (DPn), ranging from 353 to 467, than the calculated DPn on the basis of X. High molecular weight polymer was synthesized even under nonstoichiometric conditions via crystallization of oligomers and the following solid-state polymerization in the crystals. (c) 2005 Wiley Periodicals, Inc.