Synthesis and Characterization of Silver-Poly(vinyl acetate) Metal Chelate Nanocomposites

• Main Authors: Chueh-Jung Huang, 黃鵲容
• Other Authors: Fuh-Sheng Shieu
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/32021321334301922977

博士 === 國立中興大學 === 材料工程學研究所 === 93 === A new chemical route for the synthesis of metal-polymer nanocomposite has been developed. Commercial poly(vinylacetate) (PVAc) was used as polymer matrix, silver nanoparticles were generated by reduction of silver nitrate (AgNO3) in PVAc matrix, and a PVAc-AgNO3 metal chelate polymer (MCP) containing both the Ag(0) crystal and Ag(I) complex ions was obtained. The reaction mechanism of the MCP system, including the coordination of polymer-Ag(I) complexes, the reduction of Ag(I) ions and the hydrolysis of PVAc chains were investigated. The results showed that the Ag(I) cations of AgNO3 were coordinated with polymer functional groups to form polymer-Ag(I) complexes, subsequently, some of the complexed Ag(I) ions were in-situ reduced to generate Ag(0) metal in MCP system, and the structure of PVAc chains was partially hydrolyzed to form an amphiphilic PVOH/PVAc structure under the catalytic effect of reduced Ag(0) metal. To evaluate the interaction of the PVOH/PVAc chains with the reduced Ag(0), an inducing method for preparing MCP micelle solution with the use of mixed solvent/non-solvent and the morphological characterization of the generated Ag-micelles were investigated. The studies showed that a long-lasting MCP solution with stable Ag-micelles might be prepared by using a H2O/HCOOH solvent with the right composition. The TEM results showed that when the AgNO3 concentration of MCP was below 0.5 wt%, the Ag-micelles displayed a variety of Ag-corona structure, but as the AgNO3 concentration was increased to 1.0-2.0 wt%, micelles that had Ag-solid embedded in the micellar core were observed. The MCP materials that with nanosized Ag(0) and complexed Ag(I) contained in the PVAc matrix may be chemically modified by reducing agents to improve their surface metallization and electric conductivity. To evaluate the influence of such metallization upon the electric conductivity of these MCP materials, the polyethylene terephthalate (PET) was used as substrates to prepare the MCP/PET films. The studies showed that the sheet resistance (Rs) of the RMCP/PET films, which were treated with a sodium borohydride (NaBH4) aqueous solution, was at least 4 orders of magnitude lower than that of the MCP/PET films. It was also found that the electric conductivity of both MCP/PET and RMCP/PET films increased with increasing AgNO3 content. These metallized RMCP/PET films also exhibited high electromagnetic interference shielding effectiveness (EMI/SE) that is proportional to the electric conductivity.