Preparation of poly(ethylene glycol)-polystyrene block copolymers using photochemistry of dithiocarbamate as a reduced cell-adhesive coating material

This article reports a novel preparation method of poly(ethylene glycol) (P EG)-polystyrene (PST) amphiphilic block copolymers with well-defined block lengths by using photopolymerization of an iniferter, benzyl N,N-diethyldit hiocarbamate. PEG macroiniferters, which were prepared by end-capping of PE G monomethyl ethers with benzyl N,N-diethyldithiocarbamate group at one end , were irradiated with UV light in the presence of styrene (ST). NMR analys es showed that the PST block was chain-extended from the PEG block, resulti ng in the preparation of PEG-PST block copolymers. The number-average molec ular weights of the copolymers increased almost linearly with irradiation t ime, light intensity, and concentration of ST. The polydispersities of the copolymers remained relatively small throughout the reaction (M-w/M-n, appr oximate to 1.3). The composition of two PEG-PST block copolymers thus obtai ned was as follows: PEG (M-n; 1.9 x 10(3) g mol(-1))-PST (3.0 x 10(3) g mol (-1)) and PEG (4.9 x 10(3) g mol(-1))-PST (2.6 x 10(3) g mol(-1)). These co polymers were coated onto a poly(ethylene terephthalate) film surface. X-ra y photoelectron spectroscopy analyses and water wettability measurements sh owed that the PST block was enriched at the outermost layer as cast in air, whereas upon immersion into water, the PEG block was oriented toward water . Enhanced wettability was observed for the diblock copolymer with a higher PEG content. Significantly reduced cell adhesion was observed on both the coated surfaces. Thus, the PEG-PST block copolymer may function as a cell a dhesion-resistant coating which reduced cell-substrate interaction. (C) 199 9 Published by Elsevier Science Ltd. All rights reserved.