Styrene was polymerized in supercritical （sc） CO2 with benzoyl peroxide （BPO） as initiator. It was found that the polymerization was accelerated by the external magnetic field.
Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the re...Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.展开更多
Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant （bis-[2-（F-hexyl）ethyl]phosphate sodium）, water-soluble/CO2-insoluble acr...Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant （bis-[2-（F-hexyl）ethyl]phosphate sodium）, water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N＇-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 （w/c） microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2＇-azo-bisisobutyronitrile （AIBN）, cross-linked poly（acryloxyethyltrimethyl ammonium chloride） particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained.展开更多
Equilibrium sorption amount, desorption diffusion coefficients and sorption diffusion coefficients of CO2 in poly（l-lactic acid） （PLLA） films at elevated pressures were determined by the gravimetric method, in whi...Equilibrium sorption amount, desorption diffusion coefficients and sorption diffusion coefficients of CO2 in poly（l-lactic acid） （PLLA） films at elevated pressures were determined by the gravimetric method, in which the Fick＇s diffusion model was applied to analyze both the desorption and sorption processes. The equilibrium sorption amount of CO2 in PLLA increased with lowering temperature and elevating pressure at the temperature range from 40 to 60 ℃ and pressure from 10^4 to 2x10^4 kPa. Desorption diffusion coefficients were greatly influenced by the equilibrium sorption amount, and they were in the same order of magnitude as the sorption diffusion coefficients. The scan electron microscope （SEM） photos demonstrated that there was no foaming phenomenon of the PLLA film during desorption and sorption processes. The XRD spectra implied that the crystalline degree of PLLA film decreased after CO2 processing. It was concluded that PLLA polymer could be well swollen and plasticized by supercritical CO2.展开更多
Precipitation polymerizations of divinylbenzene（DVB） in pure supercritical carbon dioxide,and parallel runs with presence of a cosolvent were carried out.The results showed that use of acetone as the cosolvent contr...Precipitation polymerizations of divinylbenzene（DVB） in pure supercritical carbon dioxide,and parallel runs with presence of a cosolvent were carried out.The results showed that use of acetone as the cosolvent contributed greatly to the formation of the monodisperse microspheres.PDVB microspheres,with obviously higher uniformity than reported up to date,were achieved using 6-7 mL of acetone in a reactor of 50 mL with DVB concentration of 0.4 mol/L under 16 MPa,a much lower pressure than previously reported without use of cosolvent.展开更多
The polymerization of acrylic acid (AA) with dissolved carbon dioxide and tetrahydrofuran (THF) in the monomer is studied. Viscosity measurement. differential scanning calorimetry (DSC). and scanning electron microsco...The polymerization of acrylic acid (AA) with dissolved carbon dioxide and tetrahydrofuran (THF) in the monomer is studied. Viscosity measurement. differential scanning calorimetry (DSC). and scanning electron microscopy (SEM) indicate that the conccntration of tctrahydrofuran has pronounced effect on the molecular weight (Mn). glass transition temperature (Tg). and the morphology of the product.展开更多
The solubility of styrene from polystyrene in supercritical carbon dioxide is measuredat 323 K,333 K,and 343 K in the pressure range from 12 to 28 MPa.Based on the associationconcept and the theory of dense gas sorpti...The solubility of styrene from polystyrene in supercritical carbon dioxide is measuredat 323 K,333 K,and 343 K in the pressure range from 12 to 28 MPa.Based on the associationconcept and the theory of dense gas sorption in polymers,a displacement and association mechanismon supercritical fluid extraction of the monomer from the polymer is proposed.And,a novel math-ematical model for correlating the solubility data obtained from the experiments is also proposed inthe paper.展开更多
Al-grafted mesoporous silica zeolite materials known as Al-MCM-41 were prepared with supercritical CO2 as the media. The X-ray diffraction（XRD） patterns and N2 adsorption/desorption isotherms indicate that Al-modifi...Al-grafted mesoporous silica zeolite materials known as Al-MCM-41 were prepared with supercritical CO2 as the media. The X-ray diffraction（XRD） patterns and N2 adsorption/desorption isotherms indicate that Al-modified MCM-41 materials keep silica MCM-41 pore diameter of about 2.7 nm and the excellent structural ordering very well. The gel permeation chromatography（GPC） and1H NMR show that the polymerization of ε-caprolactone went well with butanol. It was demonstrated that compared with conventional Al-MCM-41 materials, the aluminosilicate mesoporous zeolite prepared with the aid of supercritical CO2 is a novel useful catalyst for the polymerization of ε-caprolactone.展开更多
基金This work is financially supported by National Key Basic Research Project(G2000048010)the National Natural Science Foundation of China for financial support(29725308).
文摘Styrene was polymerized in supercritical （sc） CO2 with benzoyl peroxide （BPO） as initiator. It was found that the polymerization was accelerated by the external magnetic field.
基金The Natural Science Foundation of Jiangsu Province(No.BK20130602)the Applied Basic Research Program of Suzhou(No.SYG201836)the Project of the Collaborative Innovation Center of Suzhou Nano Science and Technology
文摘Three poly(vinyl acetate)(PVAc)oligomers with controlled molecular weight and narrow molecular distribution are synthesized by reversible addition-fragmentation chain transfer(RAFT)polymerization.The effects of the reaction temperature and the added amount of initiator of the PVAc polymerization are discussed.In addition,the phase behavior of the prepared PVAc in pressured CO2 is determined via the cloud point method.The results indicate that the cloud point of PVAc increases with the increase in the molecular weight,the PVAc concentration,and the temperature.The cloud point pressures for the PVAc mass concentration of 0.12%with the molecular weight of 1 550,2 120,and 2 960 g/mol are 13.48,13.83 and 15.43 MPa,respectively,at the temperature of 35℃.It reveals that the solubility of PVAc in ScCO2 at relatively low pressure is remarkably limited.
基金This work was financially supported by the STC Program of the US National Science Foundation under Agreement No.CHE-9876674.
文摘Herein, we reported the microemulsion polymerization in supercritical carbon dioxide. With the aid of an anionic phosphate fluorosurfactant （bis-[2-（F-hexyl）ethyl]phosphate sodium）, water-soluble/CO2-insoluble acryloxyethyltrimethyl ammonium chloride monomer and N,N＇-methylene-bisacrylamide cross-linker were solubilized into CO2 continuous phase via the formation of water-in-CO2 （w/c） microemulsion water pools. Initiated by a CO2-soluble initiator, 2,2＇-azo-bisisobutyronitrile （AIBN）, cross-linked poly（acryloxyethyltrimethyl ammonium chloride） particles were produced and stabilized in these w/c internal water pools. Nano-sized particles with sizes less than 20 nm in diameter and narrow particle size distributions were obtained.
基金Supported by the National Natura Science Foundation of China （21076185）.
文摘Equilibrium sorption amount, desorption diffusion coefficients and sorption diffusion coefficients of CO2 in poly（l-lactic acid） （PLLA） films at elevated pressures were determined by the gravimetric method, in which the Fick＇s diffusion model was applied to analyze both the desorption and sorption processes. The equilibrium sorption amount of CO2 in PLLA increased with lowering temperature and elevating pressure at the temperature range from 40 to 60 ℃ and pressure from 10^4 to 2x10^4 kPa. Desorption diffusion coefficients were greatly influenced by the equilibrium sorption amount, and they were in the same order of magnitude as the sorption diffusion coefficients. The scan electron microscope （SEM） photos demonstrated that there was no foaming phenomenon of the PLLA film during desorption and sorption processes. The XRD spectra implied that the crystalline degree of PLLA film decreased after CO2 processing. It was concluded that PLLA polymer could be well swollen and plasticized by supercritical CO2.
基金This research is financial supported by National Natural Science Foundation of China(No.20904016)Natural Science Foundation of Shandong Province(No.Y2008F30)Doctoral Foundation of Shandong Province,China (No.2007BS04036)
文摘Precipitation polymerizations of divinylbenzene（DVB） in pure supercritical carbon dioxide,and parallel runs with presence of a cosolvent were carried out.The results showed that use of acetone as the cosolvent contributed greatly to the formation of the monodisperse microspheres.PDVB microspheres,with obviously higher uniformity than reported up to date,were achieved using 6-7 mL of acetone in a reactor of 50 mL with DVB concentration of 0.4 mol/L under 16 MPa,a much lower pressure than previously reported without use of cosolvent.
文摘The polymerization of acrylic acid (AA) with dissolved carbon dioxide and tetrahydrofuran (THF) in the monomer is studied. Viscosity measurement. differential scanning calorimetry (DSC). and scanning electron microscopy (SEM) indicate that the conccntration of tctrahydrofuran has pronounced effect on the molecular weight (Mn). glass transition temperature (Tg). and the morphology of the product.
基金Supported by the National Natural Science Foundation of China.
文摘The solubility of styrene from polystyrene in supercritical carbon dioxide is measuredat 323 K,333 K,and 343 K in the pressure range from 12 to 28 MPa.Based on the associationconcept and the theory of dense gas sorption in polymers,a displacement and association mechanismon supercritical fluid extraction of the monomer from the polymer is proposed.And,a novel math-ematical model for correlating the solubility data obtained from the experiments is also proposed inthe paper.
文摘Al-grafted mesoporous silica zeolite materials known as Al-MCM-41 were prepared with supercritical CO2 as the media. The X-ray diffraction（XRD） patterns and N2 adsorption/desorption isotherms indicate that Al-modified MCM-41 materials keep silica MCM-41 pore diameter of about 2.7 nm and the excellent structural ordering very well. The gel permeation chromatography（GPC） and1H NMR show that the polymerization of ε-caprolactone went well with butanol. It was demonstrated that compared with conventional Al-MCM-41 materials, the aluminosilicate mesoporous zeolite prepared with the aid of supercritical CO2 is a novel useful catalyst for the polymerization of ε-caprolactone.
