Monitoring the formation of polystyrene/silica nanocomposites from vinyl triethoxysilane containing copolymers |
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Authors: | Juan F Lopez Gabriel J Pelaez Leon D Perez |
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Institution: | 1. Grupo Ciencia de los Materiales, Instituto de Química, Universidad de Antioquia, Medellin, Colombia 2. Departamento de Química, Pontificia Universidad Javeriana, Bogota, D.C., Colombia
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Abstract: | Random copolymers of polystyrene-co-polyvinyl triethoxysilane (PS-co-PVTES) were prepared via semi-batch emulsion polymerization with different feed monomer compositions and evaluated as precursors of polystyrene (PS)/silica nanocomposites. Small-angle X-ray scattering (SAXS) profiles acquired from 20 °C to 180 °C showed that, at temperatures higher than glass transition temperature (T g) of PS, the latex particles aggregate. On thermal annealing at 180 °C, silica-rich domains are formed, as corroborated by scanning electron microscopy. Infrared spectroscopy and differential scanning calorimetry analyses showed a reduction of the silanol concentration and an increase in the T g value, respectively. The silica long domain spacing, measured by SAXS, depends on the concentration of vinyl triethoxysilane (VTES) in the feed; this value varied from 35 to 57 nm when the weight ratio of the monomers (styrene/VTES) was 50:50 and 90:10, respectively. |
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