(274d) Effect of Oxygen on Admicellar Polymerization of Styrene on Silica Surfaces

Previous studies on the formation of ultrathin polymer films on surfaces utilizing admicellar polymerization, the surface analog of emulsion polymerization, relied on unusually high ratios of initiator to monomer for free radical polymerization. The effect of oxygen on the polymer formed through admicellar polymerization on silica particles was studied using cetyltrimethylammonium bromide (CTAB) as the adsorbed surfactant bilayer template, styrene as the monomer, and azobisisobutyronitrile as the free radical initiator. The solutions were deoxygenated by purging the headspace with nitrogen prior to the initiation of the admicellar polymerization of styrene. The formed polymer thin film was extracted from the silica surface with refluxing tetrahydrofuran and characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and gel permeation chromatography (GPC). Samples were compared to control experiments performed without deoxygenation. The results demonstrated that the purging of oxygen significantly decreased termination resulting in the formation of higher molecular weight polymer. Surface characterization of the formed polymer films on the silica was accomplished with atomic force microscopy (AFM).