EPOXIDATION OF BACTERIAL POLYESTERS WITH UNSATURATED SIDE-CHAINS - I - PRODUCTION AND EPOXIDATION OF POLYESTERS FROM 10-UNDECENOIC ACID

y(3-hydroxyoctanoate-co-3-hydroxy-10-undecenoate)s (PHOUs) with contro lled amounts of unsaturated side chains were produced by Pseudomonas o leovorans from various mixtures of 10-undecenoic acid and octanoic aci d. Epoxidation of the unsaturated side chains in PHOU, by reacting the polymer with m-chloroperbenzoic acid (MCPBA) in homogeneous solution, was readily carried out. After complete epoxidation, changes in the m olecular weights and thermal transitions of the PHOUs were investigate d by gel permeation chromatography (GPC) and differential scanning cal orimetry (DSC), respectively, and the thermal stabilities of the initi al and epoxidized polymers were measured by thermogravimetric analysis (TGA). The acidic conditions used for the epoxidation reaction did no t result in a significant decrease in molecular weight of the PHOUs. T he epoxidized PHOUs were completely soluble, indicating that cross-lin king did not occur, but transformation of the vinyl groups in PHOU int o epoxide groups caused a decrease in the melting temperature and the enthalpy of melting. In contrast, the glass transition temperatures in creased in a linear manner with epoxide group content in the product p olymer, and the thermal degradation behavior of the epoxidized polymer was considerably different from that of the initial polymer.