Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means...Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.展开更多
The methyl methacrylate(MMA) reversible addition-fragmentation chain transfer(RAFT) miniemulsion polymerization in the presence of β-cyclodextrin(β-CD) was investigated. β-CD is found to act both as an efficient so...The methyl methacrylate(MMA) reversible addition-fragmentation chain transfer(RAFT) miniemulsion polymerization in the presence of β-cyclodextrin(β-CD) was investigated. β-CD is found to act both as an efficient solubilizer for RAFT agent(2-cyanopro-2-yl dithiobenzoate) and as a stabilizer for heterogeneous polymerization. The RAFT miniemulsion polymerizations with or without β-CD were compared in terms of kinetics and the molecular weight distribution. The problem of poor latex stability was observed in this system. A good result of the control over RAFT miniemulsion polymerization of MMA was obtained with β-CD. The increase of the molecular weight of poly(methyl methacrylate) shows a linear relationship with the monomer conversion. The polydispersity index of the polymer with β-CD(PDI=1.18—1.21) is smaller than that without β-CD. TEM photographs showed that the PMMA particles produced with β-CD had smooth surfaces and uniform particle size. Higher amount of sodium dodecyl sulfate and hexadecane was found in favor of improving the controllability of the system. Oil soluble initiator is beneficial to the controllability of the polymerization.展开更多
文摘Two new chiral stationary phases, 2,3 di O acetyl 6 O trimethylsilyl β cyclodextrin (DATBCD) and 2,6 di O trimethylsilyl 3 O acetyl β cyclodextrin(DTABCD), were synthesized, their structures were identified by means of infrared and NMR spectra. Capillary columns were coated with the two stationary phases by dynamic method. The chromatographic properties, and enantiomers separation, such as ketone, esters, alcohols and olefines, were investigated on the silylated and acetylated β cyclodextrin stationary phases. The experimental results show that the silylated and acetylated β cyclodextrins are suitable to be used as capillary gas chromatographic stationary phases, the relative polarity of DATBCD and DTABCD stationary phases is respectively 4143 and 3928, the column efficiencies are respectively 3084 and 4198, and DATBCD is of stronger enantioselectivity than DTABCD, capacity factor of the first eluted enantiomer ( k 1) and separation factor(α)of α phenylethanol on DATBCD stationary phase are respectively 8.23 and 1.019.
文摘The methyl methacrylate(MMA) reversible addition-fragmentation chain transfer(RAFT) miniemulsion polymerization in the presence of β-cyclodextrin(β-CD) was investigated. β-CD is found to act both as an efficient solubilizer for RAFT agent(2-cyanopro-2-yl dithiobenzoate) and as a stabilizer for heterogeneous polymerization. The RAFT miniemulsion polymerizations with or without β-CD were compared in terms of kinetics and the molecular weight distribution. The problem of poor latex stability was observed in this system. A good result of the control over RAFT miniemulsion polymerization of MMA was obtained with β-CD. The increase of the molecular weight of poly(methyl methacrylate) shows a linear relationship with the monomer conversion. The polydispersity index of the polymer with β-CD(PDI=1.18—1.21) is smaller than that without β-CD. TEM photographs showed that the PMMA particles produced with β-CD had smooth surfaces and uniform particle size. Higher amount of sodium dodecyl sulfate and hexadecane was found in favor of improving the controllability of the system. Oil soluble initiator is beneficial to the controllability of the polymerization.
