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

Ag-nanocluster doped inorganic-organic hybrid coatings were prepared on pol ycarbonate (PC) substrates. The sol was prepared by incorporating AgNO3 in a composite inorganic-organic hybrid sol derived from 3-(glycidoxypropyl)tr imethoxy silane (GLYMO)-tetraethyl orthosilicate-3-(methacryloxypropyl)-tri methoxy silane (MEMO). The hydrolysis-condensation of alkoxy groups and pol ymerization of epoxy and methacrylate groups formed the composite matrix ne twork. 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 anneali ng (100 degreesC) of former coatings (1 Ag) showed no precipitation of Ag-n anoclusters whereas the latter one (5 Ag) showed Ag precipitation. As a res ult 5 Ag films showed the characteristic absorption at 412 nm due to the su rface plasmon resonance (SPR) of Ag-nanoclusters. When these coated PCs wer e exposed to UV light, polymerization of the methacrylate groups, strengthe ning of the silica network, along with formation of Ag-nanoclusters occurre d 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.