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

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 unsaturated, 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 γ-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.