Inorganic-organic nanocomposites formed using porous ceramic particles

Inorganic-organic nanocomposites are expected to be of great significance in new material technologies impacting many different fields. We develop new nanomaterials of this type that have an interpenetrating network structure via in-situ polymerization of monomer within the nanopores of inorganic gel particles (porosity 20-80 vol.%). Due to strong nanomechanical bonding, these thermosetting polymer composites are expected to exhibit improved mechanical performance.; Particle porosity is a primary factor. In contrast to HCl-catalyzed gels, more porous HF-catalyzed gels (porosity 62 vol.%) produced higher composite wear-resistance. At the same loading, the wear rates decrease linearly with increasing filler porosity. Better wear resistance is associated with fine-scale plastic deformation as opposed to brittle fracture and particle pull-out.; For the coupling of HF-catalyzed particles with {dollar}gamma{dollar}-methacryloxypropyl trimethoxysilane, FTIR and solid-state {dollar}rmsp{lcub}13{rcub}C/sp{lcub}29{rcub}Si{dollar} NMR show that the use of a catalyst (n-propylamine) and a nonpolar solvent (cyclohexane), causes the degree of coupling and self-condensation to increase. Ethanol competes with the silane for the surface and results in less silane self-condensation. Surprisingly, the silane diminishes the composite wear resistance due to its pore-filling effect and the subsequent decrease in polymer interpenetration. A transition from plastic deformation to brittle fracture is involved.; A new sol-gel technique was found to prepare porous (up to 76.54 vol.%) silica nanoparticles from solution via sodium fluoride (NaF) salt catalysis. Full interpenetration is achieved without the use of silane coupling agents. The resulting composites displayed improved wear resistance, toughness, modulus, hardness and high compressive strength. Toughening and reinforcement can be explained by pore confinement. DMA and DEA were combined with TEM to investigate related structure and property issues.; The filler matrix effect on composite wear was evaluated utilizing the phase transformation of porous alumina gels from the stable monohydrate to the {dollar}gamma{dollar}-alumina form between 300 and 400{dollar}spcirc{dollar}C; conveniently the total amount of porosity remains the same. {dollar}gamma{dollar}-alumina is more efficient than the monohydrate in improving wear resistance. The susceptibility of the monohydrate to 'transgranular' deformation and the crack-deflection of {dollar}gamma{dollar}-alumina in an 'intergranular' mode are responsible for the similar toughening effect of these two reinforcements.