Cationic poly（styrene-co-N,N-dimethylaminoethyl methacrylate） （P（St-co-DMAEMA）） latexes were prepared in the absence of surfactant by using 2,2＇-azobis （2-methylpropionamidine） dihydrochloride （AIBA） as the...Cationic poly（styrene-co-N,N-dimethylaminoethyl methacrylate） （P（St-co-DMAEMA）） latexes were prepared in the absence of surfactant by using 2,2＇-azobis （2-methylpropionamidine） dihydrochloride （AIBA） as the initiator. The effects of the AIBA concentration, HC1/DMAEMA molar ratio and DMAEMA amount on the emulsion polymerization and the latex properties were investigated. The particle morphology and size, the zeta potential and the amino distribution of the P（St- co-DMAEMA） latexes were characterized by transmission electron microscope （TEM）, dynamic light scattering （DLS） and conductometric titration, respectively. Results showed that the emulsion polymerization performed smoothly with high monomer conversion and narrow particle size distribution under the optimized conditions with AIBA concentration of1 wt%, HC1/DMAEMA molar ratio of 1.2 and DMAEMA content of 5 wt%. The diameter of the dried latex particles decreased and the density of amino groups on the particle surfaces increased with increasing the DMAEMA content. The zeta potential of the P（St-co-DMAEMA） latexes was pH-dependent and the zero point was around at pH 7.2. A facile method was developed to fabricate P（St-co-DMAEMA）/laponite hybrid nanoparticles via electrostatic adsorption, in which the loading capacity of laponite platelets reached 17.7 wt%, and the resultant hybrid nanoparticles showed good thermal stability.展开更多
Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite ...Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.展开更多
The polymerization of methyl methacrylate (MMA) at the surface of titanium dioxide (TiO 2) particles was carried out by using soapless emulsion polymerization method. In this process, composite particles with TiO 2 ...The polymerization of methyl methacrylate (MMA) at the surface of titanium dioxide (TiO 2) particles was carried out by using soapless emulsion polymerization method. In this process, composite particles with TiO 2 core and polymer shell were obtained and thus the surface of titanium dioxide was modified. The encapsulating polymer was characterized by TEM, DTA and IR. In addition, the surface properties of the original and modified TiO 2 were studied by Zeta potential measurement and determination of contact angle and dispersability.展开更多
By using a two-stage soapless emulsion polymerization, four kinds of core-shell nanoparticles have been prepared,which are composed of a polystyrene core having an average diameter of 256 nm and a poly(methyl methacry...By using a two-stage soapless emulsion polymerization, four kinds of core-shell nanoparticles have been prepared,which are composed of a polystyrene core having an average diameter of 256 nm and a poly(methyl methacrylate-co-acrylicacid) shell. The transmission electron microscopy (TEM) micrographs and the atomic force microscopy (AFM) imagesevidenced the presence of a core-shell structure. In the infrared spectra, the shift of v_(COOH) to lower wavenumber withincreasing Eu^(3+) ion content indicates that coordination between the oxygen of the carboxylic group and Eu^(3+) has occurred.The fluorescence intensity of ~5D_0-~7F_2 transition was observed to reach its maximum with a carboxyl group molar percentageof 40% in the shell and an Eu^(3+)/--COO^- molar ratio of 1:3. The fluorescence intensity ratio of ~5D_0-~7F_2 to ~5D_0-~7F_1 transition reached its maximum with an Eu^(3+)/--COO^- molar ratio of 1:3 for all the four series.展开更多
基金financially supported by the National Basic Research Program of China(No.2014CB932202)
文摘Cationic poly（styrene-co-N,N-dimethylaminoethyl methacrylate） （P（St-co-DMAEMA）） latexes were prepared in the absence of surfactant by using 2,2＇-azobis （2-methylpropionamidine） dihydrochloride （AIBA） as the initiator. The effects of the AIBA concentration, HC1/DMAEMA molar ratio and DMAEMA amount on the emulsion polymerization and the latex properties were investigated. The particle morphology and size, the zeta potential and the amino distribution of the P（St- co-DMAEMA） latexes were characterized by transmission electron microscope （TEM）, dynamic light scattering （DLS） and conductometric titration, respectively. Results showed that the emulsion polymerization performed smoothly with high monomer conversion and narrow particle size distribution under the optimized conditions with AIBA concentration of1 wt%, HC1/DMAEMA molar ratio of 1.2 and DMAEMA content of 5 wt%. The diameter of the dried latex particles decreased and the density of amino groups on the particle surfaces increased with increasing the DMAEMA content. The zeta potential of the P（St-co-DMAEMA） latexes was pH-dependent and the zero point was around at pH 7.2. A facile method was developed to fabricate P（St-co-DMAEMA）/laponite hybrid nanoparticles via electrostatic adsorption, in which the loading capacity of laponite platelets reached 17.7 wt%, and the resultant hybrid nanoparticles showed good thermal stability.
基金the National Natural Science Foundation of China(No.20236020,20325621)the National R & D Program of China(No.2001BA310A01).
文摘Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.
文摘The polymerization of methyl methacrylate (MMA) at the surface of titanium dioxide (TiO 2) particles was carried out by using soapless emulsion polymerization method. In this process, composite particles with TiO 2 core and polymer shell were obtained and thus the surface of titanium dioxide was modified. The encapsulating polymer was characterized by TEM, DTA and IR. In addition, the surface properties of the original and modified TiO 2 were studied by Zeta potential measurement and determination of contact angle and dispersability.
基金This work was supported by the Elite Foundation of Educational Department of Guangdong Province (No. 02047).
文摘By using a two-stage soapless emulsion polymerization, four kinds of core-shell nanoparticles have been prepared,which are composed of a polystyrene core having an average diameter of 256 nm and a poly(methyl methacrylate-co-acrylicacid) shell. The transmission electron microscopy (TEM) micrographs and the atomic force microscopy (AFM) imagesevidenced the presence of a core-shell structure. In the infrared spectra, the shift of v_(COOH) to lower wavenumber withincreasing Eu^(3+) ion content indicates that coordination between the oxygen of the carboxylic group and Eu^(3+) has occurred.The fluorescence intensity of ~5D_0-~7F_2 transition was observed to reach its maximum with a carboxyl group molar percentageof 40% in the shell and an Eu^(3+)/--COO^- molar ratio of 1:3. The fluorescence intensity ratio of ~5D_0-~7F_2 to ~5D_0-~7F_1 transition reached its maximum with an Eu^(3+)/--COO^- molar ratio of 1:3 for all the four series.
