Synthesis of Poly(N,N-Dimethylacrylamide) Brushes from Functionalized Latex Surfaces by Aqueous Atom Transfer Radical Polymerization

摘要

Negatively charged, ATRP initiator functionalized polystyrene latexes were synthesized and N,N-dimethylacrylamide was polymerized from their surfaces by aqueous ATRP using several catalyst combinations. Very high grafting densities and molecular weights were achieved with good polydispersities. The brushes exhibited a strong repulsive force that increased with molecular weight in atomic force microscopy measurements. Hydrodynamic thicknesses were consistent with theory. Polymerization from these surfaces is very different from ATRP in solution and depends on monomer concentration in solution, type of catalyst, and surface initiator concentration. The observations were explained with an electrostatic model of the surface region that predicts an increase in the local concentration of Cu(Ⅰ) and Cu(Ⅱ) catalyst complexes.