Monomer of 7-methacryloyloxy-4-methylcoumarin （MAOMC） was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate （BOEMA） at different feed composit...Monomer of 7-methacryloyloxy-4-methylcoumarin （MAOMC） was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate （BOEMA） at different feed compositions were prepared by free radical solution polymerization at （70 ± 1） ℃ in ethylmethylketonc （EMK） using benzyl peroxide （BPO） as an initiator. The copolymers were characterized by FTIR and IH-NMR spectroscopy. Thermogravimetric analysis （TGA） and differential scanning calorimetry （DSC） of the copolymers showed moderate thermal stability and higher Tg values. Gel permeation chromatography （GPC） was used to find out the molecular weights of the different copolymers. Antibacterial activities of the copolymers were also investigated against the selected pathogenic bacteria＇s. The antibacterial activity of the copolymer increases as the MAOMC content increases in the copolymer. This shows that coumarin moiety plays a very important role in the antibacterial activity.展开更多
Un-doped and Co-doped ZnO nanoparticles （NPs） with different weight ratios （0.5, 1.0, 1.5, and 2.0 wt% of Co） were synthesized by a facile and rapid microwave-assisted combustion method using urea as a fuel. The p...Un-doped and Co-doped ZnO nanoparticles （NPs） with different weight ratios （0.5, 1.0, 1.5, and 2.0 wt% of Co） were synthesized by a facile and rapid microwave-assisted combustion method using urea as a fuel. The prepared NPs were characterized by X-ray diffraction （XRD）, high resolution scanning electron microscopy （HR-SEM）, energy dispersive X-ray analysis （EDX）, diffuse reflectance spectroscopy （DRS）, photoluminescence （PL） spectroscopy and vibrating sample magnetometry （VSM）. XRD patterns refined by the Rietveld method indicated that Co-doped ZnO had a single pure phase with wurtzite structure suggesting that Co^2＋ ions would occupy Zn^2＋ ionic sites within the ZnO crystal lattice. Interestingly, the morphology was found to convert substantially from grains to nanoparticles with close-packed periodic array of hexagonal-like shape and then into randomly distributed spherical NPs with the variation of Co-content. The optical band gap estimated using DRS was found to be red-shifted from 3.22 eV for the un-doped ZnO NPs then decrease up to 2.88 eV with increasing Co-content. PL spectra showed a strong green emission band thus confirming the formation of pure single ZnO phase. Magnetic studies showed that Co-doped ZnO NPs exhibited room temperature ferromagnetism （RTFM） and that the saturation magnetization attained a maximum value of 2.203 × 10^-3 emu/g for the highest Co-content. The antibacterial studies performed against a set of bacterial strains showed that the 2.0 wt% Co-doped ZnO NPs possessed a greater antibacterial effect.展开更多
文摘Monomer of 7-methacryloyloxy-4-methylcoumarin （MAOMC） was synthesized and characterized by FTIR, 1H-NMR and 13C-NMR spectroscopy. Copolymers of MAOMC with butoxyethylmethacrylate （BOEMA） at different feed compositions were prepared by free radical solution polymerization at （70 ± 1） ℃ in ethylmethylketonc （EMK） using benzyl peroxide （BPO） as an initiator. The copolymers were characterized by FTIR and IH-NMR spectroscopy. Thermogravimetric analysis （TGA） and differential scanning calorimetry （DSC） of the copolymers showed moderate thermal stability and higher Tg values. Gel permeation chromatography （GPC） was used to find out the molecular weights of the different copolymers. Antibacterial activities of the copolymers were also investigated against the selected pathogenic bacteria＇s. The antibacterial activity of the copolymer increases as the MAOMC content increases in the copolymer. This shows that coumarin moiety plays a very important role in the antibacterial activity.
文摘Un-doped and Co-doped ZnO nanoparticles （NPs） with different weight ratios （0.5, 1.0, 1.5, and 2.0 wt% of Co） were synthesized by a facile and rapid microwave-assisted combustion method using urea as a fuel. The prepared NPs were characterized by X-ray diffraction （XRD）, high resolution scanning electron microscopy （HR-SEM）, energy dispersive X-ray analysis （EDX）, diffuse reflectance spectroscopy （DRS）, photoluminescence （PL） spectroscopy and vibrating sample magnetometry （VSM）. XRD patterns refined by the Rietveld method indicated that Co-doped ZnO had a single pure phase with wurtzite structure suggesting that Co^2＋ ions would occupy Zn^2＋ ionic sites within the ZnO crystal lattice. Interestingly, the morphology was found to convert substantially from grains to nanoparticles with close-packed periodic array of hexagonal-like shape and then into randomly distributed spherical NPs with the variation of Co-content. The optical band gap estimated using DRS was found to be red-shifted from 3.22 eV for the un-doped ZnO NPs then decrease up to 2.88 eV with increasing Co-content. PL spectra showed a strong green emission band thus confirming the formation of pure single ZnO phase. Magnetic studies showed that Co-doped ZnO NPs exhibited room temperature ferromagnetism （RTFM） and that the saturation magnetization attained a maximum value of 2.203 × 10^-3 emu/g for the highest Co-content. The antibacterial studies performed against a set of bacterial strains showed that the 2.0 wt% Co-doped ZnO NPs possessed a greater antibacterial effect.
