Nano-Silver/Polymer Composites Synthesized Synchronously In Situ Emulsion Polymerization Ultrasonically

The ultrasonic radiation technique was introduced to synthesize nanomaterials, and nanosilver particles, nanosilver/polymer composites particles were prepared through ultrasonic cavitation with unique dispersion, crushing, activation, initiation action. The obtained nanomaterials were characterized by means of ultraviolet-visible spectra (UV), infrared spectroscopy (IR), high resolution transmission electron microscopy (HRTEM), transmission electron microscopy (TEM), differential scanning calorimetry-thermogravimetry (DSC-TG), X-ray diffraction (XRD), Laser Zetasizer analysis and so on.The mixture solution consisted of the silver nitrate and polyvinyl alcohol(PVA) dissolved in water was acted by ultrasound wave and the silver ion in the solution was reduced to silver atom, then silver clusters during the process of ultrasonicating. The results of UV Spectra suggested that the nano-silver was formed and the maximal absorbing peak shifted to long wave. The photos of TEM showed that the average size of nano-silver particulate was about 15—25 nm, which was equal to that by Zetasizer, and that nano-silver particulate were fractal assembling into ordered dendritical aggregation structure.Silver-polymethyl methacrylate nanocomposites were successfully synthesized in the emulsion containing methyl methacrylate monomers and silver salt but neither initiator nor reductant contained in situ by ultrasonic radiating. The resultant Ag/PMMA nanocomposites were characterized by IR, HRTEM and XRD, and the results showed that nano-silver as core within the composites particles was uniform, polycrystalline and high order crystalline, and that there existed some degree of interaction between silver particles and polymer matrix. The content of polymer in the composites had some effect on nano-silvers crystallization. The effects of the experimental conditions such as systemic temperature and contents of components on the final conversion of monomer and molecular weight of PMMA were also researched. The interesting phenomenon was found that the polymerization was promoted by silver clusters, and the polymerization of monomer didn't occur without silver nitrate. The polymerization of monomer procreated easily in the presence of silver nitrate and the monomer conversion increased with silver nitrate increasing below its critical concentration. The thermal analysis results of the composites particles showed that decomposition of PMMA as shell within the...