Chemical and microbiological degradation of polycaprolactone prepared under different synthesis conditions

Polycaprolactone (PCL) polymer samples with different molecular weights (30–33 000) were synthesized using gallium-containing catalysts for ring-opening polymerization of ε-caprolactone. The synthesized polymer samples were characterized by a set of physicochemical methods (GPC, IR spectroscopy, NMR). The processes of chemical degradation of the synthesized polymers were studied. The complete dissolution and degradation of polymer molecules, including to 6-hydroxycaproic acid, in an aqueous-ethanol solution (1: 1 v/v) of caustic soda (1 M NaOH) was shown to be achieved at 65 °C within 30 h with permanent stirring (300 rpm). The compositions of the prepared solutions were studied by IR spectroscopy and ¹H and ¹³C NMR spectroscopy. The solutions obtained after the destruction of various PCL were tested as components of culture media for growth of various microorganisms and biocatalytic transformation into diverse products: biogas, bacterial nanocellulose, biomass of oil-degrading bacterial cells, and microalgae. The two-stage process was proposed for PCL waste processing, which corresponds to requirements of the modern environmental standards from the viewpoint of safety and resource saving.