Zhihua Gan1 and Yoshiharu Doi1,2
1SORST Group of Japan Science and Technology Corporation (JST),
Polymer Chemistry Laboratory, RIKEN Institute, Hirosawa 2-1, Wako-shi, Saitama 351-0198, Japan
2Department of Innovative and Engineered Materials, Tokyo Institute of Technology, Nagatsuta 4259, Midori-ku, Yokohama 226-8502, Japan
Among the various physical properties of biodegradable polymers, biodegradability is the most essential and important property. The biodegradability of polymer is determined by the chemical structure, and also greatly influenced by the solid-state structure, especially the crystal structure, crystal size and crystallinity. Therefore, clear demonstration of the relationship among the chemical structure, physical properties, and biodegradation behavior is of great significance for the property improvement and molecular design of biodegradable polymers. This paper reviews our previous works on the crystallization kinetics, crystal structure and morphology of biodegradable polyesters: poly(ethylene succinate) (PES), poly(butylene succinate-co-ethylene succinate) [P(BS-co-ES)] aliphatic copolyester, and poly(butylene adipate-co-butylene terephthalate) [P(BA-co-BT)] aliphatic-aromatic copolyesters, and discusses the influence of solid-state structure on the biodegradation behavior. The morphologies of lamellar crystals before and after enzymatic degradation have been visualized by atomic force microscopy, and the results reveal that although the enzyme is able to initiate the degradation of a lamellar crystal from its chain-folded surface and laterally chain-packing edges, the successive degradation of the lamellar crystal is determined mainly by the crystal structure and the crystal growth mechanism. Investigations on the aliphatic-aromatic P(BA-co-BT) copolyesters have indicated that the copolyesters are biodegradable only when short BT chain sequences are located in the amorphous phase or in the crystalline phase. The influence of BT content on the crystal structure, crystal size and crystallinity as well as the thermal properties of P(BA-co-BT) copolyesters has been examined here and a correlation to biodegradability is shown.
論文來源：In Commemoration of The 50 Years of Polymer Education and Research at Peking University,May,2004
