Mesoporous silica-reinforced polymer nanocomposites

This research reports the use of organic-modified mesoporous silica particles as fillers to form organic/inorganic nanocomposites with improved thermal and mechanical properties. The particle fillers were synthesized by co-assembly of surfactant and silicate species prepared by hydrolysis and condensation reactions of tetraethoxysilane (TEOS) and (3-trimethoxysilyl)propyl methacrylate (TMSPMA) through an aerosol process. Selective surfactant removal resulted in mesoporous particles with high surface areas and with covalently bound propyl methacrylate ligands on the pore surface as indicated by XRD, TEM, N-2 adsorption-desorption, FTIR, C-13 NMR, Si-29 NMR, and other techniques. Infiltration and subsequent in situ polymerization of (3-trimethoxysilyl)propyl methacrylate within and among the mesoporous silica particles result in nanocomposites with improved mechanical and thermal properties. Mechanical testing shows a significant increase in tensile strength, modulus, and toughness of the nanocomposites with little sacrifice on the elongation relative to the bulk poly((3-trimethoxysilyl)propyl methacrylate). DSC and SEM results indicate that chemical bonding and strong interactions between the polymer and filler, confined segmental motion of the polymer chains within the mesoporous channels, and the use of the silica particles as pseudo-cross-linking points may contribute to the improved mechanical properties.