Poly(acrylic acid) with disulfide bond for the elaboration of pH-responsive brush surfaces

We report on a new route for the facile preparation of pH-responsive tethered brushes on metallic surfaces, starting from poly(acrylic acid) (PAA) containing a disulfide (S–S) bond (PAA–S–S–PAA). First, atom transfer radical polymerization (ATRP) of 1-ethoxyethyl acrylate (EEA) with a disulfide-containing initiator was performed to obtain the poly(EEA) precursor polymer (PEEA–S–S–PEEA). Deprotection of PEEA by a heating step resulted in the desired PAA chains without any further purification. The brushes, obtained by the ‘grafting to’ of PAA–S–S–PAA onto gold, were then characterized by atomic force microscopy in water at various pH values. The results evidence a large collapsing/swelling capacity.