Influence of sulphonation on polymer and polymer blend surfaces studied by atomic force microscopy

Films of immiscible blends of polystyrene (PS) and poly(methyl methacrylate) (PMMA) on silicon wafers were prepared by spin-coating and subsequently modified by sulphonation with sulfuric acid. The weight ratios of the polymer blends were 1:3 and 3:1. The increase of the PS fraction combined with chemical treatment of the blends with sulfuric acid results in an increase in surface wettability by water. This correlation can be understood by investigating the influence of these parameters on the surface of the polymer blends by atomic force microscopy. To determine the distribution of PS and PMMA within the polymer blends we used cyclohexane and acetic acid as selective solvents for PS and PMMA, respectively, and compared the coating topography before and after treatment with the solvents. Copyright (C) 2001 John Wiley & Sons, Ltd.