Papers by Keyword: Inorganic Nanoparticles

Abstract: Membrane separation technique is widely applied because of simple operation, high separation efficiency, and no induction of phase transformation, but it is restricted from some fields by the high pollution, low strength and small flux of polymeric membranes. Improving the performances is one major way to expand the applied fields of polymer membranes, and so far, it has been realized by introduction of inorganic hybrid nanoparticles into polymer membranes. Inorganic nanoparticles can modify the surface and structural properties and largely improve the hydrophilicity, contamination resistance and rejection performance of membranes, and thus expand the adaptability of polymer membranes. In this review, we summarized the advances in modification of polymer membranes with nanomaterials including nanoZnO, nanoAg, nanoTiO₂, nanoSiO₂ and multi-walled carbon nanotubes (MWNTs). The prospects in the future development are finally provided.

Abstract: Polymer swelling by scCO2 was mainly studied to understand many industrial processes, especially in the field of pharmacy for drug delivery (impregnation) and also polymer processing by CO2-assisted extrusion. We have studied here another application of polymer swelling by scCO2 for the synthesis of nanocomposites. The selected model system was the direct synthesis of copper nanoparticles in a poly(ethylene glycol) matrix (PEG). The study of the formation of nanostructures in polymer matrix is constituted of three main steps: i) thermodynamical behaviour of the polymer/CO2 system, ii) viscosity of the polymer/CO2 system and iii) nucleation and growth of copper nanoparticles. First, the thermodynamical behaviour of the PEG/CO2 system was studied by in situ IR spectroscopy. This method gives accurate values of the polymer swelling by scCO2 but also of the CO2 sorption in the polymer. For example, at 40°C-15MPa, the swelling of PEG is equal to 35% for a CO2 solubility of 23 wt%. Secondly, we have developed an original falling ball viscometer for the determination of PEG viscosity as a function of CO2 density. A good knowledge of the polymer/CO2 system is finally used for the control of formation of copper nanoparticles. This formation was followed by in situ UV - visible spectroscopy and characterized by transmission electron microscopy.