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 degreesC) 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 I Ag films whereas coarsening of Ag-nanoclusters resulted in the case of 5 Ag films. (C) 2001 Elsevier Science B.V. All rights reserved.