Selective deposition of metals on plastics used in the construction of microanalytical devices: Photo-directed formation of metal features on PMMA

We describe here, for the first time, the use of amine-terminated poly(methyl methacrylate), AT-PMMA, surfaces as a substrate for the electroless deposition of An nanoparticle films (Au-EDNPFs), the adsorptive deposition of An colloids, the laterally patterned formation of Au-EDNPFs, and the use of the patterned Au-EDNPFs to form electrolessly deposited Ag films with micrometer features. Au-EDNPFs were formed by chemical reduction of AuCl4- films coordinated to AT-PMMA sheets. The Au-EDNPFs act as autocatalytic substrates for the conventional electroless deposition of Ag. Such Ag films can be used in the construction of functional Ag/AgCl reference electrodes. In addition, sequentially deposited, multilayer An colloid films formed on the AT-PMMA surfaces are shown to be effective electrochemical working electrodes in aqueous media. In the final portion of the work, laterally patterned (selective) deposition of Ag films was accomplished by photoremoval of photolabile protecting groups attached to the amine functionalities of AT-PMMA, followed by the Au-EDNPF formation process and subsequent electroless deposition of Ag onto the Au-EDNPF surface. The selectivity of the Au-EDNPF pattern formation process (deposition on only the deprotected amine sites and not the protected sites) is shown to be dictated by the pH of the AuCl4- solution in contact with the photodeprotected surfaces.