Fabrication of Novel Biointerfaces Using High-Density Polymer Brushes

Living radical polymerization has been applied to surface-initiated graft polymerization, allowing controlled grafting of well-defined polymers from various solid surfaces with dramatically high surface densities. This density was more than 1 order of magnitude higher than those of typical semidilute brushes, going deep into the concentrated brush regime. This project aimed at clarifying the properties of concentrated polymer brushes as novel biointerfaces. The main results are as follows.(1) The protein adsorption as well as the cell adhesion could be much reduced on the concentrated brushes of hydrophilic polymers because of their size-exclusion effect and dynamic properties. This excellent inertness of the concentrated brush in the interaction with the proteins should afford the system long-term stability against biofauling.(2) Photo-induced organotellurium-mediated living radical polymerization successfully applied to the preparation of the hydrophilic brushes.(3) Combinatorial technique was established to fabricate a brush surface with continuous variation of graft density and chain length, clarifying the crossover density of concentrated/semi-dilute brushes.(4) An excellent frictional property was macroscopically demonstrated fix the system of a concentrated-brush and gel surfaces.(5) The concentrated brushes of poly (N-isopropylacrylamide) were synthesized and studied on their properties of swelling/deswelling, friction, and protein adhesion.(6) A new and novel technique was established to immobilize initiators on polymeric substrates as well as various metal surfaces.