Metallization of crosslinked epoxy resins derived from diglycidyl ethers of poly(ethylene glycol) and bisphenol a by reduction of polymer-incorporated cobalt ion

The surface of the blend films of poly(ethylene glycol) diglycidyl ether (PEG-E) and bisphenol A diglycidyl ether (BPA-E) cured with 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride at 200°C for 5 h was metallized by the reduction of polymer-incorporated cobalt acetate with aqueous sodium borohydride at 20–50°C. Although the cured films of PEG-E/BPA-E, weight ratio 100/0–80/20, were successfully metallized, the blend ratio 60/40 did not afford a metallized film by this reduction method. The glass transition temperature (T_g) of the cured resin measured by dynamic viscoelastic analysis rose with an increase of BPA-E content. The difficulty of surface metallization in the case of blend ratio 60/40 is related to the hindrance of migration of cobalt ion due to the restriction of molecular chain motion. Electron probe microanalysis and X-ray photoelectron spectroscopy measurement revealed that the cobalt ion that was homogeneously distributed in the inner part of the film before reduction migrated to both sides of the film and then was reduced to pure metal by the reduction treatment. The X-ray diffraction analysis of the reduced films revealed that the generated cobalt was almost amorphous. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2164–2169, 2004