Synthesis, characterization, and properties of tethered polystyrene-b-polyacrylate brushes on flat silicate substrates

Surface-immobilized polystyrene-b-polyacrylate brushes have been synthesized on silicate substrates from chlorine-terminated polystyrene (PS) brushes by atom transfer radical polymerization (ATRP). ATRP of methyl methacrylate (MMA), methyl acrylate (MA), and (N,N-dimethylamino) ethyl methacrylate (DMAEMA) produced tethered diblock copolymer brushes, which were characterized by ellipsometry, FTIR-ATR, tensiometry, and XPS. "Control" polymerizations supported a radical mechanism for the MMA polymerization. The thickness of the polyacrylate terminal block was controlled by free initiator concentration. All three diblock copolymer brushes underwent self-reorganization and exhibited different surface properties in response to different solvent treatments. For PS-b-PMMA and PS-b-PMA blushes, treatment with CH2Cl2 resulted in localization of PMMA and PMA at the air interface; treatment with cyclohexane localized the PS block at the air interface. PS-b-PDMAEMA brushes exhibited a similar behavior using cyclohexane and THF/H2O (v/v = 1:1).