Poly(ester-anhydrides) with controlled molecular weight and structure

Abstract

We report on the synthesis of a series of poly(ester-anhydride) composed of the following dicarboxylic acids: adipic, suberic, sebacic, dodecanedioic acids; and hydroxyalkanoic acids: ricinoleic and 12-hydroxystearic acid with control molecular weight approaching from a new method in which well-defined ester monomers are first synthesized by stepwise addition of hydroxyalkanoic acids molecules into melted dicarboxylic acids. The key advantage of the synthesis of ester monomers in this modified method is the full consumption of hydroxy acid devoid of any self-condensation. The ester monomers are then activated using variable amounts of acetic anhydride followed by melt condensation polymerization. The molecular weights of the synthesized poly(ester-anhydride) are highly controllable depending upon the degree of activation of the ester monomers; hence the amount of acetic anhydride. All the synthesized poly(ester-anhydrides) are thoroughly characterized by 1H NMR, Fourier transform infrared, and gel permeation chromatography.