Macromolecules, Vol.42, No.22, 8655-8660, 2009
Stimuli-Responsive Surfaces Utilizing Cleavable Polymer Brush Layers
A new set of materials has been developed that allow for the preparation of coatings with stimuli-responsive surfaces relying on acid-sensitive polymer brush layers. A functionalized methacrylate monomer, 5-(2-bromo-2-methylpropanoyloxy)-2,5-dimethyhexan-2-yl methacrylate, was synthesized and added to a photopolymerizable solution consisting of ethoxylated bisphenol A dimethacrylate, N-vinylpyrrolidone, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol trimethacrylate, and 2,2-dimethoxy-2-phenylacetophenone. Thin films of this solution were spin-coated onto silicon wafers and cured. These substrates were placed into a reactor under atom transfer radical polymerization conditions which accomplished the growth of it polystyrene polymer brush layer from the photopolymer surface. Because of the acid-sensitive nature of the brush tether group, the brush layers could be selectively cleaved from the surface by treatment with a p-toluenesulfonic acid/dioxane solution. All surfaces were fully characterized before and after modification. The cleaved polymer from the brush layer was collected and characterized using gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR).