The Influence of Ozone on the Structure of Biodegradable Matrices Based on Mixtures of Poly(3-Hydroxybutyrate), Polylactide, and Chitosan

Changes in fibrous and film materials based in mixtures of biodegradable polyesters of polyhydrobutyrate, polylactide, and chitosan polysaccharide were studied using structural-dynamic method EPR involving a stable nitroxyl radical-a TEMPO probe-during ozonolysis. The fibers and films were obtained from solutions in chloroform using methods of electroforming and pouring on glass, respectively. It was shown that lower density of packing in amorphous regions of the mixture samples determines an increased rate of their oxidation with ozone as compared with homopolymers. A two-stage kinetic mechanism of ozonolysis was demonstrated, which includes the formation of side groups and subsequent destruction of the polymer chain. It was established that the probe rotation activation energy depends on the amount of the polymer in the mixture, while the activation barrier is minimal for mixtures of polyesters in the same range of concentrations, where the constants of ozonolysis are maximal. It was shown that the presence of chitosan in ternary compositions leads to an increase in the degree and rate of ozonolysis.