A Facile Route to Poly(acrylic acid) Brushes Using Atom Transfer Radical Polymerization

We report the preparation of a poly(acrylic acid) polymer brush from a flat silica substrate using a surface-initiated atom transfer radical polymerization of tert -butyl acrylate. Significantly, we use a chemical free deprotection strategy through pyrolysis of the tert -butyl esters to the corresponding carboxylic acids. This eliminates the possibility of loss of the polymer brush from the surface via acidolysis of the ester group in the surface bound initiator. We have verified the formation of the poly(acrylic acid) brush through ATR-FTIR, ellipsometry, water contact angle analysis, and XPS. We also demonstrate the stimuli-responsive nature of these brushes with respect to pH and added electrolyte concentration.