This paper describes the synthesis and free radical polymerization of 2,5 bis(4′ alkyloxyphenyl)styrene(M n ) for mesogen jacketed liquid crystal polymers(MJLCPs), where p terphenyl subsituted by alkoxy groups at bot...This paper describes the synthesis and free radical polymerization of 2,5 bis(4′ alkyloxyphenyl)styrene(M n ) for mesogen jacketed liquid crystal polymers(MJLCPs), where p terphenyl subsituted by alkoxy groups at both ends was used as mesogenic unit. Because of the absence of the polar linkage groups, such as —COO— or —CONH— as employed in the previous reported MJLCPs, M n is believed to be polymerized easily by both free radical polymerization and ionic polymerization. The chemical structure of M n was proved by 1H NMR, mass spectrometry and elementary analysis. Their phase transition and liquid crystallinity were characterized by DSC and POM. Although M 1, M 2, M 3 and M 4 exhibited monotropic nematic mesophase, M 5 displayed enantiotropic nematic mesophase presumably because of its decreased melting transition temperature. All monomers were easily polymerized to moderately high molecular weight polymers. At elevated temperature above T g, poly[2,5 bis(4′ alkoxyphenyl)styrene] showed a very stable mesophase. The formed birefrigence did not disappear until thermal decomposition started. Compared to other MJLCPs, the polymers reported here have much higher thermal stability. [WT5HZ]展开更多
Living" radical polymerization of methyl methacrylate was investigated using a new initiating system, i.e. DCDPS/FeCl 3/PPh 3, in which diethyl 2,3 dicyano 2,3 diphenyl succinate(DCDPS) is a hexa substituted etha...Living" radical polymerization of methyl methacrylate was investigated using a new initiating system, i.e. DCDPS/FeCl 3/PPh 3, in which diethyl 2,3 dicyano 2,3 diphenyl succinate(DCDPS) is a hexa substituted ethane thermal iniferter. The polymerization mechanism belongs to a reverse ATRP process. The polymerization was closely controlled in bulk at 75 ℃, polymethyl methacrylate(PMMA) with a high molecular weight and quite narrow polydispersity ( M w/ M n=1 20—1 29) was obtained. End group analysis by 1H NMR spectroscopy shows that the resulting PMMA is ω functionalized by a chlorine atom, which is also confirmed by the chain extension reaction in the presence of CuCl/bipy catalyst via a conventional ATRP process. [WT5HZ]展开更多
Living radical polymerization of methyl methacrylate was investigated using a new initiation system, i. e. DCDPS/Fe(DC)3, in which diethyl 2,3-dicyano-2,3-diphenyl-succinate(DCDPS) is a hexa-substituted ethane thermal...Living radical polymerization of methyl methacrylate was investigated using a new initiation system, i. e. DCDPS/Fe(DC)3, in which diethyl 2,3-dicyano-2,3-diphenyl-succinate(DCDPS) is a hexa-substituted ethane thermal iniferter and ferric tri(diethyldithiocarbamate)(Fe(DC)3) is a ligand-free catalyst. The polymerization was successfully controlled in bulk at 95 ℃, PMMA with high molecular weight and quite narrow polydispersities(Mw/Mn=1.20～1.29) were obtained. End group analysis by 1H NMR spectroscopy shows that the resulting PMMA is ω-functionalized by a DC group.展开更多
A β-diketone-bridged chromophore-containing acrylic monomer, 1-(4-dimethylaminophenyl)-4-methyl-4-pentene-1,3-diketone(DMPDK) and its saturated model compound, 1-(4-dimethyl aminophenyl)-1,3-butanedione(DMBDK) were s...A β-diketone-bridged chromophore-containing acrylic monomer, 1-(4-dimethylaminophenyl)-4-methyl-4-pentene-1,3-diketone(DMPDK) and its saturated model compound, 1-(4-dimethyl aminophenyl)-1,3-butanedione(DMBDK) were synthesized and investigated by spectroscopy. It was found that the fluorescence intensity of DMPDK was much lower than that of DMBDK at the same concentration, which indicates that DMPDK, a β-diketone-bridged acrylic monomer having chromophore moiety, also showed fluorescence structural self-quenching effect(SSQE). Photo-induced tautomerization of DMBDK in acetonitrile was studied by means of UV and fluorescence spectroscopy. The results imply that the fluorescence method is capable of monitoring tautomerization of some fluorescent β-diketones.展开更多
文摘This paper describes the synthesis and free radical polymerization of 2,5 bis(4′ alkyloxyphenyl)styrene(M n ) for mesogen jacketed liquid crystal polymers(MJLCPs), where p terphenyl subsituted by alkoxy groups at both ends was used as mesogenic unit. Because of the absence of the polar linkage groups, such as —COO— or —CONH— as employed in the previous reported MJLCPs, M n is believed to be polymerized easily by both free radical polymerization and ionic polymerization. The chemical structure of M n was proved by 1H NMR, mass spectrometry and elementary analysis. Their phase transition and liquid crystallinity were characterized by DSC and POM. Although M 1, M 2, M 3 and M 4 exhibited monotropic nematic mesophase, M 5 displayed enantiotropic nematic mesophase presumably because of its decreased melting transition temperature. All monomers were easily polymerized to moderately high molecular weight polymers. At elevated temperature above T g, poly[2,5 bis(4′ alkoxyphenyl)styrene] showed a very stable mesophase. The formed birefrigence did not disappear until thermal decomposition started. Compared to other MJLCPs, the polymers reported here have much higher thermal stability. [WT5HZ]
文摘Living" radical polymerization of methyl methacrylate was investigated using a new initiating system, i.e. DCDPS/FeCl 3/PPh 3, in which diethyl 2,3 dicyano 2,3 diphenyl succinate(DCDPS) is a hexa substituted ethane thermal iniferter. The polymerization mechanism belongs to a reverse ATRP process. The polymerization was closely controlled in bulk at 75 ℃, polymethyl methacrylate(PMMA) with a high molecular weight and quite narrow polydispersity ( M w/ M n=1 20—1 29) was obtained. End group analysis by 1H NMR spectroscopy shows that the resulting PMMA is ω functionalized by a chlorine atom, which is also confirmed by the chain extension reaction in the presence of CuCl/bipy catalyst via a conventional ATRP process. [WT5HZ]
文摘Living radical polymerization of methyl methacrylate was investigated using a new initiation system, i. e. DCDPS/Fe(DC)3, in which diethyl 2,3-dicyano-2,3-diphenyl-succinate(DCDPS) is a hexa-substituted ethane thermal iniferter and ferric tri(diethyldithiocarbamate)(Fe(DC)3) is a ligand-free catalyst. The polymerization was successfully controlled in bulk at 95 ℃, PMMA with high molecular weight and quite narrow polydispersities(Mw/Mn=1.20～1.29) were obtained. End group analysis by 1H NMR spectroscopy shows that the resulting PMMA is ω-functionalized by a DC group.
文摘A β-diketone-bridged chromophore-containing acrylic monomer, 1-(4-dimethylaminophenyl)-4-methyl-4-pentene-1,3-diketone(DMPDK) and its saturated model compound, 1-(4-dimethyl aminophenyl)-1,3-butanedione(DMBDK) were synthesized and investigated by spectroscopy. It was found that the fluorescence intensity of DMPDK was much lower than that of DMBDK at the same concentration, which indicates that DMPDK, a β-diketone-bridged acrylic monomer having chromophore moiety, also showed fluorescence structural self-quenching effect(SSQE). Photo-induced tautomerization of DMBDK in acetonitrile was studied by means of UV and fluorescence spectroscopy. The results imply that the fluorescence method is capable of monitoring tautomerization of some fluorescent β-diketones.
基金supported by the National Natural Science Foundation of China (20129001)the Research Grants Council of Hong Kong, China(CA05/06.SC02)R/D Fund of Shenzhen University, China (200824)~~
