The sol-gel process is considered very valuable though unfortunately still not fully understood. Better insight into the kinetic and mechanism of the sol-gel reaction to prepare silica nano-particles in rubber matrix is provided by a detailed SAXS and NMR time-resolved study. In addition, silica formation at higher reaction temperatures was further explored for the purpose of possible industrial application. The sol-gel process in rubber matrix adopts similar behavior as mini-emulsion where hexylamine, used as catalyst, behaves as surfactant forming inverse micelles with enclosed water in TEOS-swollen rubber matrix. So called 'hairy' silica particles are observed with hexylamine and remnant ethoxy groups residing on the silica surface or/and inner core, assigning more hydrophobic silica nature thus better rubber-silica interactions  . Increase of ethanol during sol-gel reaction (1HMAS-NMR) corresponds to increase in size of silica particle (SAXS) with reaction time .  Structure of powder sol-gel silica: 13C (1H) CP/MAS HETCOR

Novel insights of the structure and formation of silica nano-particles via sol-gel reaction in rubber matrix

243rd National Meeting (2012)

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