Two cationic thermoresponsive stationary phases were designed and prepared containing poly [ N-isopropylacrylamide-co-（ 2-dimethylamino ） ethylmethacrylate ] and poly [ N-isopropylacryl- amide-co-（2-diethylamino） ...Two cationic thermoresponsive stationary phases were designed and prepared containing poly [ N-isopropylacrylamide-co-（ 2-dimethylamino ） ethylmethacrylate ] and poly [ N-isopropylacryl- amide-co-（2-diethylamino） ethylmethacrylate] via a simple method, the direct copolymerization of monomers with double bonds on silica surfaces. The two copolymers were synthesized by radical polymerization and then characterized using Fourier transform infrared and gel permeation chroma- tography. The thermoresponsive property and amounts of copolymers grafted on silica were deter- mined through transmittance measurements and thermogravimetric analysis, respectively. The copol- ymers grafted silica particles were then applied as high-performance liquid phase （HPLC） stationary phases for chromatographic separation. Chromatographic properties of mobile phases at different pH values were evaluated by changing temperatures and using benzene and hydrocortisone as the test an- alytes. Retention time of the analytes was prolonged with increasing temperature on both thermore- sponsive columns due to enhanced hydrophobic interaction between analytes and stationary phases. The resolution increased with increasing pH of mobile phase. The optimal separation was obtained at phosphate buffer solution （ 10 raM, pH 8. 0） and at 50 ℃. The pH of mobile phase had a crucial effect on separation efficiency. The results illustrated that poly（ N-isopropylacrylamide-co-（2-diethyl- amino） ethylmethacrylate ] copolymer modified silica was more advantageous for the temperature-re- sponsive chromatographic separation because its lower critical solution temperature was relatively lower compared to the poly [ N-isopropylacrylamide-co-（2-dimethylamino） ethylmethacrylate ] sta- tionary phase.展开更多
采用连续原子转移自由基聚合途径制备了两亲性三嵌段聚合物聚乙二醇-聚甲基丙烯酸N,N-二甲氨基乙酯-聚甲基丙烯酸正丁酯(PEG-PDMAEMA-PBMA),利用核磁共振氢谱(1 H NMR)和凝胶渗透色谱(GPC)对聚合物结构及分子量进行了表征.动态光散射(D...采用连续原子转移自由基聚合途径制备了两亲性三嵌段聚合物聚乙二醇-聚甲基丙烯酸N,N-二甲氨基乙酯-聚甲基丙烯酸正丁酯(PEG-PDMAEMA-PBMA),利用核磁共振氢谱(1 H NMR)和凝胶渗透色谱(GPC)对聚合物结构及分子量进行了表征.动态光散射(DLS)和透射电镜(TEM)结果证实该聚合物的自组装行为具有pH敏感性.通过改变水溶液的pH值可以精确地调控聚合物的自组装行为,从而获得胶束、纳米球、大囊泡和小囊泡等多种自组装结构.这些自组装结构的形成与PDMAEMA链段的质子化程度和聚合物的亲疏水平衡有关.展开更多
基金Supported by the National Natural Science Foundation of China(20675008)
文摘Two cationic thermoresponsive stationary phases were designed and prepared containing poly [ N-isopropylacrylamide-co-（ 2-dimethylamino ） ethylmethacrylate ] and poly [ N-isopropylacryl- amide-co-（2-diethylamino） ethylmethacrylate] via a simple method, the direct copolymerization of monomers with double bonds on silica surfaces. The two copolymers were synthesized by radical polymerization and then characterized using Fourier transform infrared and gel permeation chroma- tography. The thermoresponsive property and amounts of copolymers grafted on silica were deter- mined through transmittance measurements and thermogravimetric analysis, respectively. The copol- ymers grafted silica particles were then applied as high-performance liquid phase （HPLC） stationary phases for chromatographic separation. Chromatographic properties of mobile phases at different pH values were evaluated by changing temperatures and using benzene and hydrocortisone as the test an- alytes. Retention time of the analytes was prolonged with increasing temperature on both thermore- sponsive columns due to enhanced hydrophobic interaction between analytes and stationary phases. The resolution increased with increasing pH of mobile phase. The optimal separation was obtained at phosphate buffer solution （ 10 raM, pH 8. 0） and at 50 ℃. The pH of mobile phase had a crucial effect on separation efficiency. The results illustrated that poly（ N-isopropylacrylamide-co-（2-diethyl- amino） ethylmethacrylate ] copolymer modified silica was more advantageous for the temperature-re- sponsive chromatographic separation because its lower critical solution temperature was relatively lower compared to the poly [ N-isopropylacrylamide-co-（2-dimethylamino） ethylmethacrylate ] sta- tionary phase.
文摘采用连续原子转移自由基聚合途径制备了两亲性三嵌段聚合物聚乙二醇-聚甲基丙烯酸N,N-二甲氨基乙酯-聚甲基丙烯酸正丁酯(PEG-PDMAEMA-PBMA),利用核磁共振氢谱(1 H NMR)和凝胶渗透色谱(GPC)对聚合物结构及分子量进行了表征.动态光散射(DLS)和透射电镜(TEM)结果证实该聚合物的自组装行为具有pH敏感性.通过改变水溶液的pH值可以精确地调控聚合物的自组装行为,从而获得胶束、纳米球、大囊泡和小囊泡等多种自组装结构.这些自组装结构的形成与PDMAEMA链段的质子化程度和聚合物的亲疏水平衡有关.
