Copper-encapsulated polystyrene nanocomposite particles were prepared through ex situ dispersion of Cu nanoparticles into monomer droplets and subsequent polymerization using water in supercritical carbon dioxide (water-in-sc-CO 2 ) at 70 C. First, colloidal dispersion of copper nanoparticles was synthesized by chemical reduction of copper chloride (CuCl 2 ) using sodium borohydrate (NaBH 4 ) as reducing agent. Colloidal dispersion of copper nanoparticles was added slowly during the polymerization of styrene using water-in-sc-CO 2 medium at 70 C and 20.68 MPa. Cu nanoparticle encapsulated polymer particles were characterized by UV, X-ray diffraction, thermogravimetric analysis, SEM, and TEM. Cu nanoparticles were uniformly distributed inside the polymer matrix during the polymerization process. This work represents a simple way to prepare a variety of metal nanoparticles encapsulated polymer particles using waterin-sc-CO 2 medium. The Cu/polystyrene nanocomposite particles exhibit antimicrobial activity against a number of bacteria. The current work represents a simple, cheap and universal way to prepare a variety of metal-polymer nanocomposite materials.
Poly(3-phenyl azomethine ethylthiophene) (PPAET) and poly(3-phenyl azomethine butylthiophene) (PPABT) have been synthesized by the oxidative coupling method using FeCl 3 as the oxidant. The polymers were thoroughly characterized using Fourier-transform infrared (FTIR) spectroscopy, 1 H nuclear magnetic resonance (NMR) spectroscopy, and elemental analysis. The concomitant thermal, optical, and electrochemical properties of the polymers revealed that they possess excellent potential as photovoltaic materials. The electrochemical bandgaps of PPAET and PPABT are calculated to be 2.19 eV and 2.14 eV, respectively. The absorption spectra showed broad absorption over the wavelength range of 350 nm to 590 nm with a maximum absorption peak at 407 nm and 415 nm (k max ), respectively, for PPAET and PPABT. Polymer photovoltaic cells based on blends of polymers and TiO 2 nanoparticles have been fabricated, and the power conversion efficiencies (PCE) of the photovoltaic cells were measured to be 0.102% and 0.125%, respectively, for PPAET and PPABT.
Polystyrene microparticles were synthesized by emulsion polymerization in supercritical carbon dioxide (sc-CO 2 using (polydimethylsiloxane) (PDMS) as a surfactant/stabilizer and azobisisobutyronitrile (AIBN) as initiator. The emulsion polymerization was carried out by varying pressures within the range 13.79-17.93 MPa. At the end of polymerization, powdered polymeric micoparticles were collected by depressurizing CO 2 . The powdered polymeric microparticles were characterized by SEM, GPC, DSC and TGA. The influence of pressure on conversion, molecular weight, particle size and polydispersity index was studied. The molecular weight (Mn) of the polymer is in the range of 35,542 to 45,078 g/mol. Polydispersity index is in the range of 1.45-1.86 and particle size in the range of 3 25 m-6 3 m.
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