Copolymerization effect on morphology of polymer crystals prepared from 4-acetoxybenzoic acid and 4-(4-acetoxyphenyl)benzoic acid

We had been studying a dual self-assembling polycondensation system by means of phase separation of oligomers, which is a novel polycondensation system to prepare separately the two kinds of polymer crystals having different structures. This phenomenon was induced by the difference in the oligomer interaction such as hydrogen bonding. In this study, a dual self-assembling polycondensation was found in the solution polymerization of 4-acetoxybenzoic acid (ABA) and 4-(4-acetoxyphenyl)benzoic acid (APBA). Two different kinds of crystals were simultaneously formed, of which one was needle-like crystal and another was fibrillated slab-like crystals. These morphologies resembled those of corresponding homopolymer crystals. Microscopic FT-IR analysis suggested that these two crystals had different structure. The miscibility of the oligomers prepared from APBA was quite lower than those from ABA, and this large difference in the miscibility may induce the simultaneous formation of two kinds of crystals having different crystal habit.