Melt-crystallized crystal morphology and enzymatic degradation mechanism of aliphatic polyester

Crystal morphology of melt-crystallized poly(ethylene succinate) (PES) thin film with a thickness of –100 nm was studied by atomic force microscopy (AFM). The fibril-like and wide or lozenge-shaped PES lamellar crystals under different crystallization conditions are thought to be corresponding to the crystal growth kinetics based on the secondary nucleation theory that there are two regimes of regime II and regime III with a transition temperature around 71◦C. The enzymatic degradation was conducted on the surface of melt-crystallized PES thin film by a PHB depolymerase from P.stutzeri and the lamellar crystal morphologies before and after degradation were examined by AFM. Lamellar crystals were found to degrade into many small fragments which have the same thickness with that of crystal before degradation. The involved degradation mechanism was discussed.