Construction of hydroxyl‐terminated poly(N‐isopropylacrylamide) brushes on silicon wafer via surface‐initiated atom transfer radical polymerization

Abstract

AbstractSurface‐initiated atom transfer radical polymerization (SI‐ATRP) of N‐isopropylacrylamide (NIPAM) on silicon wafer in the presence of 2‐mercaptoethanol (ME) chain transfer agent was conducted in attempt to create controllable hydroxyl‐terminated brushes. The initiator‐immobilized substrate, was prepared by the esterification of hydroxyl groups on silicon wafer with 2‐bromopropionyl bromide (2‐BPB); followed by the ATRP of NIPAM using a catalyst system, that is, Cu(I)Br/2,2′‐bipyridine (2,2′‐bpy) and a chain transfer agent, that is, ME. The formation of homogeneous tethered poly(N‐isopropylacrylamide) (poly(NIPAM) brushes with hydroxyl end‐group, whose thickness can be tuned by chancing ME concentration, is evidenced by using the combination of grazing angle attenuated total reflectance‐Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, ellipsometry, atomic force microscopy, gel permeation chromatography, and water contact‐angle measurements. The calculation of grafting parameters from experimental measurements indicated the synthesis of densely grafted poly(NIPAM) films with hydroxyl end‐group on silicon wafer and allowed us to predict a ME concentration for forming a “brush” conformation for the chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3880–3887, 2010