In situ polymerisation as a route towards transparent nanocomposites: Time-resolved light and neutron scattering experiments

We describe the formation of a highly transparent nanocomposite using an in situ polymerisation of monodisperse, 50 nm diameter, colloidal silica coated with 3-(trimethoxysilyl)propyl methacrylate (TPM) dispersed in methyl methacrylate (MMA). We demonstrate that it is possible to follow the polymerisation process in a completely non-invasive way using time-resolved dynamic light scattering and small-angle neutron scattering. These experiments allow us to obtain quantitative information on the time dependence of the resulting mechanical and structural properties during the synthesis. We observe a qualitative change between diffusive and subdiffusive motion for the dispersed nanoparticles at the gel point, in agreement with the behaviour of other colloidal systems undergoing a sol–gel transition. The small-angle neutron scattering experiments clearly demonstrate that the initial liquid-like order of the nanoparticles is maintained during the polymerisation process, and that there is no indication for particle aggregation. This information is confirmed by TEM experiments of the final nanocomposite.