Surface Patterned Graft Copolymerization of Hydrophilic Monomers onto Hydrophobic Polymer Film Upon UV Irradiation

A random copolymer [p(MMA/DMAB)] composed of methyl methacrylate (MMA) and 2,2-dimethoxy-1,2-di(4-methacryloyloxy) phenylethane-1-one (DMAB), which can simultaneously act as a photoradical initiator and crosslinkable monomer, was prepared by free radical random copolymerization. A hydrophobic film on quartz glass was prepared using p(MMA/DMAB) by a spin-coating technique. Hydrophilic methacrylic acid (MA) and 2-methacryloyloxyethyl phosphorylcholine (MPC) were graft-copolymerized from the hydrophobic p(MMA/DMAB) film in water by photo-cleavage of the DMAB unit. The graft copolymer of MA and MPC was characterized by infrared and X-ray photoelectron spectroscopies and contact angle measurements. To confirm that MPC can be grafted onto the surface of the film selectively at only UV-irradiated sites, photoinduced graft copolymerization of MPC using a photomask was performed to prepare a pMPC patterned p(MMA/DMAB) film. The film was stained using a rhodamine 6G dye that can absorb specifically to pMPC to confirm the pMPC pattern. The p(MMA/DMAB) film can be applied to various fields including photolithography and biomedical applications, because the film surface properties can be controlled using various vinyl monomers selectively on UV-irradiated sites. (C) 2014 Wiley Periodicals, Inc.