Substituent effects in surface-initiated ATRP of substituted styrenes

Surface initiated atom transfer radical polymerization (ATRP) of substituted styrenes leads to rapid synthesis of uniform and thick substituted polystyrene brushes (>100 nm in 1 h) from gold surface. High growth rates were observed for styrenes substituted with electron withdrawing groups in meta/para positions. The effects seen in surface and solution polymerizations are similar for styrenes with electron withdrawing groups, and for electron donors in ortho and para positions. However, electron donors at meta sites have surprisingly fast growth rates, which may be due to steric inhibition of termination. The overall surface polymerization rates for substituted styrenes was analyzed and found to follow the Hammett relation with rho = 0.51. The ratio of k(p) to k(t), is as an indicator of the likelihood that a reaction will reach high degrees of polymerization before termination. (C) 2015 Elsevier B.V. All rights reserved.