Surface modification of natural substrates by atom transfer radical polymerization

Surface modification of various solid polysaccharide substrates was conducted by grafting methyl acrylate (NU,) and styrene via atom transfer radical polymerization (ATRP) to produce well-defined polymer grafts. The hydroxyl groups on the surfaces of the substrates were reacted with 2-bromoisobutyryl bromide followed by graft copolymerization under ATRP conditions. The studied substrates were filter paper, microcrystalline cellulose, Lyocell fibers, dialysis tubing, and chitosan films. The modified Substrates were analyzed by FT-IR, water contact angle measurements, TGA, and SEM. FT-IR characterization of the grafted substrates showed significant differences between the different substrates in the amount of grafted polymer. Higher amounts of polymer seem to be possible to graft from native cellulose substrates than from regenerated cellulose substrates. To investigate whether the grafted polymers were living after a longer time period, a second layer of polystyrene was grafted from a filter paper modified with PMA one year ago. FT-IR characterization of the filter paper showed a peak corresponding to styrene, indicating that a block copolymer had been formed on the surface. Graft copolymerization can be used to change and tailor the surface properties of the polysaccharide substrates. (c) 2006 Wiley Periodicals, Inc.