Control of Environmental Responses on the Surface of Multiphase Polymers for Molecular Design of Biomaterials

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The surface study is very important for molecular design of polymeric biomaterials because the materials interact with organism on their surface but not in the bulk. In particular, the polymer surface may be changeable by responding to environment because of its low surface energy and flexible molecules. The purpose of this study is to clarify the mechanism of the formation and environmental responses of the surface for multiphase polymers and to establish synthesis methods of the functional polymers having environmental responsibility. The results obtained in this study are as follows :Various multiphase copolymers were synthesized in the techniques of telechelic polymers and macromonomers. In formation of the polymer surface in an air atmosphere the surface was covered by the low surface energy component, but in immersion in water the surface composition was rearranged rapidly to be covered almost completely by another component, and such compositional rearrangement was reversible. This ability was greater for graft copolymers than for block copolymers. For the three-component graft copolymers having a block copolymer as a graft three-layr structure was observed in the vicinity of the surface. This suggests that the graft component chains have a unique conformation near the surface owing to the surface energy difference between their components. Furthermore, environmental responses were studied for the copolymers having glassy and crystalline component chains. The glassy component showed environmental responsibility on the surface. This may mean that the glass transition temperature on the surface is lower than that in the bulk. On the other hand, the crystalline components were rigid for responsibility.