UV free-radical polymerization for micropatterning poly(ethylene glycol)-containing films

We have developed novel techniques for the preparation of micropatterned structures from thin films prepared by the block copolymerization of monomers using UV free-radical polymerizations. The process involves polymerizing the first monomer layer in the presence of an iniferter (initiator-transfer agent-terminator) with a dithiocarbamate group to make a photosensitive polymer. Upon application of a second monomer layer on the first polymer layer and irradiation, a copolymer is formed between the two layers. Patterns are created on the films by applying a mask and selectively irradiating the surface. We have successfully polymerized poly(ethylene glycol) (PEG) onto a highly crosslinked material of poly(ethylene glycol) dimethacrylate. Various patterns have been created to determine the precision that can be achieved with this method. Preliminary results show that the patterns in the second monomer layer can be from 5 mum to 100 mum thick, with feature size as small as 5 mum, allowing the use of this material to high aspect ratio structures for micro-fluidics. In addition, applications of this type of material are also in bioMEMS, biomaterials, and biosensors for the selective adhesion of cells and proteins.