Silver-nanocluster-doped inorganic–organic hybrid coatings on polycarbonate substrates

Ag-nanocluster doped inorganic–organic hybrid coatings were prepared on polycarbonate (PC) substrates. The sol was prepared by incorporating AgNO3 in a composite inorganic–organic hybrid sol derived from 3-(glycidoxypropyl)-trimethoxy silane (GLYMO)–tetraethyl orthosilicate–3-(methacryloxypropyl)-trimethoxy silane (MEMO). The hydrolysis–condensation of alkoxy groups and polymerization of epoxy and methacrylate groups formed the composite matrix network. The coating compositions with respect to the equivalent silver metal and silica were 1 mol% Ag–99% SiO2 and 5 mol% Ag–95% SiO2. Thermal annealing (100°C) of former coatings (1 Ag) showed no precipitation of Ag-nanoclusters whereas the latter one (5 Ag) showed Ag precipitation. As a result 5 Ag films showed the characteristic absorption at 412 nm due to the surface plasmon resonance (SPR) of Ag-nanoclusters. When these coated PCs were exposed to UV light, polymerization of the methacrylate groups, strengthening of the silica network, along with formation of Ag-nanoclusters occurred simultaneously. The UV curing induced generation of Ag-nanoclusters in 1 Ag films whereas coarsening of Ag-nanoclusters resulted in the case of 5 Ag films.