A water-soluble pH-responsive molecular brush of poly(N,N-dimethylaminoethyl methacrylate) grafted polythiophene

We report the synthesis of a new polythiophene (PT)-based molecular brush (PT-g-PDMA) by growing poly(N,N-dimethylaminoethyl methacrylate) (PDMA) chains from the PT backbone by ATRP. The polymer shows a reversible pH response in aqueous solution. A combination of AFM, light scattering, and H-1 NMR measurements indicated that the polymer brush forms a more extended conformation with a decrease in pH from 8 to 2 due to the protonation of the Me2N- groups and increased repulsive interactions among the PDMA side chains, which drives the red shift of the absorption and PL spectra of the PT backbone. The good solubility of this polythiophene-based brush in a wide range of solvents is attractive for the fabrication of functional polymer composites.