ABIOTIC AGING OF WATER-SOLUBLE 3-HYDROXYBUTYRIC ACID OLIGOMERS AS MONITORED BY CAPILLARY-ZONE-ELECTROPHORESIS

Oligomers of poly(3-hydroxybutyric acid) (P(3-HB)) were prepared by pa rtial degradation of high molecular weight P(3-HB) dissolved in 1,2-di chloroethane/water mixture in the presence of p-toluene sulfonic acid (p-TSA). The water-soluble fraction of the resulting oligomers was ext racted from the mixture with neutral sodium phosphate buffer. Capillar y zone electrophoresis showed that the aqueous extracts were composed of two series of oligomers. The first one was composed of one to seven P(S-HB) oligomers (O(3-HE)). In contrast, the second series was compo sed of four oligomers characterized by the presence of a terminal C=C bond [O'(3-HB)]. Both series of oligomers behaved differently insofar as their fate in aqueous medium was concerned. The O(3-HE) compounds w ere stable over a period of 2 months. On the other hand, the populatio n of the O'(3-HE) oligomers varied, the proportion of oligomers increa sing with aging time.