Preparation of aromatic polyesters by using fractional polycondensation under shearing condition

We have found that poly(p-oxybenzoyl) (POB) was selectively prepared by the fractional polycondensation of p-acetoxybenzoic(p-ABA) acid and m-acetoxybenzoic acid in poor solvents by using the phase separation of oligomers, and shearing was of importance for the fractionability. In this study, fractional polycondensation of POB was examined in the copolymerization of p-ABA and 3-(4-acetoxyphenyl)propionic acid (p-APPA) to clarify the shearing effect on the fractionability. This copolymerization had also fractionability and the precipitates rich in p-oxybenzoyl moiety were selectively obtained. The shearing enhanced the fractionability and the content of p-oxybenzoyl moiety of the precipitates prepared at the content of ABA in feed of 70mol% was 92.6%, which was almost POB. The shearing increased the solubility of cooligomers and therefore, this provided the suitable circumstance that homo-oligomers were selectively phase-separated.