Selective carboxylate induced thermal degradation of bacterial poly(3-hydroxybutyrate-co-4-hydroxybutyrate) - Source of linear uniform 3HB4HB oligomers

摘要

Study on bacterial poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P(3HB4HB)) thermal degradation employing mild reaction conditions and carboxylate salt is described. The chemical structure of the obtained oligomers was determined with the aid of ~1H NMR and ESI-mass spectrometry techniques. The comparison of a non-volatile degradation products obtained via carboxylate-induced thermal degradation of the P(3HB4HB) with products of the model polymer pyrolysis revealed significant differences in structure of the resulting oligomers. Exclusive formation of linear oligomers terminated with unsatu-rated, on one end, and carboxyl, on the other end, groups was noticed in case of base-catalyzed degradation contrary to oligomers produced via pyrolysis which contained also macrocyclic structures and y-butyrolactone. Moreover, the elaborated method demonstrates the ability to produce well-defined oligomers with controlled molar mass. The resulting oligomers have huge potential as macroinitiators or macromonomers and can be useful for further synthesis of more sophisticated polymeric materials.