A new precursor for conducting polymer-based brush interfaces with electroactivity in aqueous solution

We present the synthesis of a novel conducting polymer (CP) incorporating both pyrrole and thiophene units in its monomer, which is also substituted with an initiator for grafting of sidechains by atom-transfer radical polymerisation (ATRP). The precursor monomer for the CP macroinitiator, 2-(2,5-di(pyrrol-2-yl) thiophen-3-yl)ethyl 2-bromopropanoate) (PyThon) is very readily electropolymerised at low monomer concentrations and low applied potentials. Density functional theory (DFT) predictions of ionisation potentials and spin-charge distribution for PyThon are in good agreement with these experimental results. We present also the grafting of sidechains from electropolymerised PolyPyThon (PPyThon) to yield surface-confined polymer brushes. Functionalisation with polystyrene (PS), poly(2,3,4,5,6- pentafluorostyrene) (PFS) and poly(ethylene glycol) methyl ether acrylate (PEGMEA) is demonstrated and confirmed by FT-IR and water contact angle measurements. These PPyThon-based molecular brushes are electroactive in both water and acetonitrile, and show evidence of changes in surface conformation related to the redox state of the CP. The growth of human fibroblasts on PPyThon films is also demonstrated, indicating good biocompatibility of the polymer. We conceive PPyThon-based molecular brushes as a substrate for electrical stimuli-responsive surfaces with application particularly in the biomedical field.