A silica/epoxy resin nanocomposite exhibiting high thermal stability and low thermal expansion based on the uniform dispersion of hydrophilic colloidal silica nanospheres

The present study fabricated high-performance silica/epoxy resin nanocomposites having a low coefficient of linear thermal expansion (CTE) and a high glass transition temperature ( T _g ). This was accomplished by dispersing colloidal silica nanospheres having hydrophilic surfaces in epoxy resins, which limited the motion of the polymer chains. Nanocomposites were produced wherein isolated primary particles of colloidal silica without silane surface modification were dispersed uniformly. These particles were generated via the breakdown of loosely bound agglomerates of spherical silica particles during the agitation of a dispersion in an epoxy resin solution. Hydrogen bonding between hydroxyl groups on the hydrophilic surfaces of the dispersed silica nanoparticles and the cross-linked epoxy polymer network evidently limited thermally-induced motion of the polymer chains, resulting in a considerable reduction in the CTE and an increase in the T _g for the nanocomposite.