A novel surface photo-graft polymerization method for fabricated devices.

This paper presents a new photo-graft polymerization method that permits surface modification of complex shaped devices. The principle is based on photochemistry of the dithiocarbamate group, as a polymerization initiator-transfer agent-terminator (iniferter), which is capable of photochemical dissociation into a radical pair. The procedure is as follows: first, coating of a photosensitive polymer on a substrate, and subsequent ultraviolet (UV) light irradiation in the presence of a monomer. The photosensitive polymer prepared was a radical copolymer of styrene and vinylbenzyl N,N-diethyldithiocarbamate. Surface graft polymerization of a water soluble monomer (N,N-dimethylacrylamide) on poly(ethylene terephthalate) pre-coated with the photosensitive polymer was achieved. Because the photopolymerization proceeded via a living radical polymerization, the control of molecular weight of the grafted polymer was feasible. This was quantitatively observed by graft polymerization on a quartz crystal microbalance (QCM) that can detect the weight increase with the sensitivity of ng-order. Two-dimensional patterning of cultured cells was demonstrated to show how surface grafted polymerization is limited on UV light irradiation portions with dimensionally micron order precision.