Organically modified silica (ORMOSIL) bearing imidazolium Based ionic liquid prepared by hydrolysis/co-condensation of silane precursors: Synthesis, characterization and use in epoxy networks

Organically modified silica (ORMOSIL) bearing N-methyl imidazolium ionic liquid covalently attached to the silica particle was prepared by one pot sol-gel route through the hydrolysis/co-condensation of 1-(3-trimethoxysilylpropyl)-3-methyl imidazolium chloride (IL-TMOS) with tetraethoxy-silane (TEOS), catalyzed by ammonium hydroxide. The presence of IL-TMOS precursor favors the gel formation with a very short time (around 5 min for IL-TMOS/TEOS molar ratio of 0.05). The gelation time, surface area and morphology were significantly affected by the amount of IL-TMOS during the sol-gel synthesis. Higher amount of the silylated ionic liquid precursor resulted in silica structure with decreased average surface area and pore volume probably because of the co condensation interparticles. The ionogel-based ORMOSIL (IL-ORMOSIL) was compounded with epoxy prepolymer, whose dispersion was influenced by the amount of the ionic liquid tethered on the silica nanoparticles as observed by rheological properties of the uncured dispersions and by transmission electron microscopy of the cured epoxy networks. The addition of the IL-ORMOSIL resulted in a decrease in glass transition temperature without affecting the storage modulus, as indicated by dynamic-mechanical measurements. (C) 2016 Elsevier Ltd. All rights reserved.