Crosslink polymerization kinetics of poly(acrylic acid-co-2-acrylamido-2-methylpropane sulfonic acid),AA/AMPS hydrogels,was investigated by using dilatometry in the presence of sodium persulfate as initiator and N,N...Crosslink polymerization kinetics of poly(acrylic acid-co-2-acrylamido-2-methylpropane sulfonic acid),AA/AMPS hydrogels,was investigated by using dilatometry in the presence of sodium persulfate as initiator and N,N'-methylene bis(acrylamide) as crosslinker.It was found that the reaction for the crosslink polymerization of AA/AMPS hydrogels had orders of 0.58,1.14,and 0.86 with respect to the initiator,AMPS,and AA,respectively.From the Arrhenius plots,the activation energy of the crosslink polymerization was found to be about 140 and 89 kJ·mol-1 in the presence and absence of the crosslinker,respectively,in the temperature range from 45 to 65 °C.It was noted that the crosslinker had effects on the reaction order of the initiator and the activation energy due to the formation of cross-linked networks,which was verified by Fourier transfer infrared (FTIR) spectrum.To further confirm the influences of the cross-linked network structure on kinetic parameters of the crosslink polymerization,a mechanism was proposed,which highlights the different termination routes between free radical polymerization and crosslink polymerization.These results suggest that dilatometry provides a convenient tool for crosslink polymeri-zation study,and confirm that the cross-linked networks are formed in the crosslink polymerization.展开更多
An efficient and practical route to various 3-alkoxylquinoxalin-2(1 H)-ones through visible-light photocatalytic C(sp^2)-H/O-H cross-dehydrogenation coupling of quinoxalin-2(1 H)-ones and alcohols,employing ambient ai...An efficient and practical route to various 3-alkoxylquinoxalin-2(1 H)-ones through visible-light photocatalytic C(sp^2)-H/O-H cross-dehydrogenation coupling of quinoxalin-2(1 H)-ones and alcohols,employing ambient air as an oxidant at room temperature under metal-free conditions,was developed.展开更多
A novel bifunctional dye containing spirobenzopyran and cinnamoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated. The colo...A novel bifunctional dye containing spirobenzopyran and cinnamoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated. The colourless bifunctional dye in film or solution exhibits unusual photochromism through structural and geometrical transformation from spirobenzopyran to merocyanine accompanying with photocrosslinking reaction in cinnamoyl moieties. Two kinds of photochemical reaction were achieved by irradiation at the different wavelengths of monochrome UV light (275 nm, 365 nm) selectively. The photochromic process of the bifunctional dye was discussed and the dynamic behaviors of the decolorization process were investigated.展开更多
基金Supported by the National Natural Science Foundation of China(20176007 20376087)
文摘Crosslink polymerization kinetics of poly(acrylic acid-co-2-acrylamido-2-methylpropane sulfonic acid),AA/AMPS hydrogels,was investigated by using dilatometry in the presence of sodium persulfate as initiator and N,N'-methylene bis(acrylamide) as crosslinker.It was found that the reaction for the crosslink polymerization of AA/AMPS hydrogels had orders of 0.58,1.14,and 0.86 with respect to the initiator,AMPS,and AA,respectively.From the Arrhenius plots,the activation energy of the crosslink polymerization was found to be about 140 and 89 kJ·mol-1 in the presence and absence of the crosslinker,respectively,in the temperature range from 45 to 65 °C.It was noted that the crosslinker had effects on the reaction order of the initiator and the activation energy due to the formation of cross-linked networks,which was verified by Fourier transfer infrared (FTIR) spectrum.To further confirm the influences of the cross-linked network structure on kinetic parameters of the crosslink polymerization,a mechanism was proposed,which highlights the different termination routes between free radical polymerization and crosslink polymerization.These results suggest that dilatometry provides a convenient tool for crosslink polymeri-zation study,and confirm that the cross-linked networks are formed in the crosslink polymerization.
文摘An efficient and practical route to various 3-alkoxylquinoxalin-2(1 H)-ones through visible-light photocatalytic C(sp^2)-H/O-H cross-dehydrogenation coupling of quinoxalin-2(1 H)-ones and alcohols,employing ambient air as an oxidant at room temperature under metal-free conditions,was developed.
文摘A novel bifunctional dye containing spirobenzopyran and cinnamoyl moiety has been prepared and its photochromic behavior following irradiation at different wavelengths of monochrome UV light was investigated. The colourless bifunctional dye in film or solution exhibits unusual photochromism through structural and geometrical transformation from spirobenzopyran to merocyanine accompanying with photocrosslinking reaction in cinnamoyl moieties. Two kinds of photochemical reaction were achieved by irradiation at the different wavelengths of monochrome UV light (275 nm, 365 nm) selectively. The photochromic process of the bifunctional dye was discussed and the dynamic behaviors of the decolorization process were investigated.