Surface Enrichment of Hydrophilic or Hydrophobic Segment for Fine Biointerfaces

Poly(trimethylene carbonate) (PTMC) is of great interest from the viewpoint of applications in various biomedical materials. Ring-opening polymerization of trimethylene carbonate (TMC) can yield PTMC by the activation of the hydroxyl group in the presence of organic catalysts. By using hydrophilic or hydrophobic compounds as initiation points, we can evaluate a state of surface enrichment for each initiation compound. In the present study, cholesterol derivatives and a series of poly(ethylene glycol) were selected as initiation points. Cholesterol derivatives, including cholesterol, lithocholic acid, and cholic acid, were used. A series of poly(ethylene glycol), including hydroxyl groups on both terminals and monomethyl ether, were used. The resulting polymers were coated on a substrate. By measuring the static contact angle, we observed that PTMC including a hydrophobic segment, had a hydrophobic surface. On the other hand, PTMC including hydrophilic initiation points had a hydrophilic surface. This paper reports the surface enrichment of the hydrophilic or hydrophobic segment by changing the surrounding environment. For fine connecting biointerfaces, initiation points, including carboxyl groups, may be used to synthesize new materials by connecting with another molecule with an amino group via an amide bond.