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Microwave-Assisted Synthesis of Nanomaterials and Nanocomposites
Citation:
VARMA, R. S. AND M. N. Nadagouda. Microwave-Assisted Synthesis of Nanomaterials and Nanocomposites. Presented at GCMEA 2008 - MAJIC 1st, Otsu, JAPAN, August 04 - 08, 2008.
Impact/Purpose:
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Description:
The aqueous preparation of nanoparticles using vitamins B1 and B2, and vitamin C which can function both as reducing and capping agents prompted us accomplished the bulk syntheses of Ag and Fe nanorods using polyethylene glycol (PEG) under microwave (MW) irradiation conditions; the formation of nanorods of uniform size and shape were found to depend on the concentration of PEG used. Bulk and shape-controlled synthesis of gold (Au) nanostructures with various shapes such as prisms, cubes, and hexagons was accomplished via MW-assisted spontaneous reduction of noble metal salts using aqueous solution of a-D-glucose, sucrose or maltose. The expeditious reaction was completed under MW irradiation in 30-60 s and can be applied to the generation of nanospheres of Ag, Pd, and Pt. Nanocomposites of polyvinyl alcohol (PVA) cross-linked metallic systems such as Pt, Cu, and In, and bimetallic systems such as Pt-In, Ag-Pt, Pt-Fe, Cu-Pd, Pt-Pd and Pd-Fe were prepared expeditiously by reacting the respective metal salts with 3 wt. % PVA under MW irradiation, maintaining the temperature at 100 0C, a radical improvement over the methods for preparing cross-linked PVA described in the literature. The general preparative procedure is versatile and provides a simple route to useful metallic and bimetallic nanocomposites with various shapes, such as nanospheres, nanodendrites and nanocubes. The protocol was extended to nanocomposites of PVA cross-linked with SWNT, MWNT and C-60 and the formation of biodegradable carboxymethyl cellulose (CMC) composite films with noble nanometals. A facile MW method that accomplishes alignment and decoration of noble metals on carbon nanotubes (CNT) wrapped with carboxymethyl cellulose (CMC) will be also be presented. Although noble metal-decorated CNT composites are obtainable at room temperature the aligned nanocomposites could only be generated by exposing them to MW irradiation.