Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads wereemployed successfully for the ring-opening polymerization of 5, 5-dimethyl-1, 3-dioxan-2-one (DTC) for the first tim...Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads wereemployed successfully for the ring-opening polymerization of 5, 5-dimethyl-1, 3-dioxan-2-one (DTC) for the first time.Different polymerization conditions such as enzyme concentration and reaction temperature were studied. Immobilized PPLexhibits higher activity than native PPL. Along wth the increasing enzyme concentration, the molecular weigh of resultingPDTC decreases. PPL immobilized on narrow distributed micron-sized glass beads has outstanding recyclability. For thethird recycle time, immobilized PPL exhibits the highest catalytic activity and with high activity even after the fifth recyletime for the synthesis of PDTC. The ~1H-NMR spectra indicate that decarboxylation does not occur during the ring-openingpolymerization.展开更多
This work was directed to develop a novel method for the synthesis of hyperbranched polymers by combining enzymatic ring-opening polymerization(ROP) with self-condensing vinyl copolymerization(SCVCP). Functionalized P...This work was directed to develop a novel method for the synthesis of hyperbranched polymers by combining enzymatic ring-opening polymerization(ROP) with self-condensing vinyl copolymerization(SCVCP). Functionalized PCL was prepared by ROP of ε-CL with HEMA as the initiator and catalyzed by Novozyme 435, and subsequently converted to AB* macroinimer by the esterification with 2-bromoisobutyryl bromide. The target polymer was obtained by SCVCP of AB* macroinimer with styrene via ATRP.展开更多
Porcine pancreas lipase(PPL) immobilized on narrow distributed micron glass beads was employed successfully for ring-opening polymerization of ε-caprolactone(CL).Different polymerization conditions such as enzyme con...Porcine pancreas lipase(PPL) immobilized on narrow distributed micron glass beads was employed successfully for ring-opening polymerization of ε-caprolactone(CL).Different polymerization conditions such as enzyme concentration,reaction temperature and reaction time were studied.The results showed that M_n of the resulting PCL was significantly increased compared with that catalyzed by PPL.Higher temperature and longer reaction time both contributed to gaining PCL with a higher molecular weight,while the yield had almost no change.In addition,for evaluating the recyclibilty of immobilized PPL on narrow distributed micron glass beads for the ring-opening polymerization of CL,we adopted the most severe reaction conditions(180 ℃,(240 h)) in the recycling experiments.It was found that the recovered immobilized PPL could be used again with a compatible high catalytic activity.The highest M_n of 21 300 of PCL could be obtained at a mass fraction of 5.18% of the reused immobilized PPL at 180 ℃ for 240 h,which is the highest M_n of PCL catalyzed by PPL.The excellent recyclability of immobilized PPL on narrow distributed micron glass beads is very helpful to its further industry applications.展开更多
As an alternative biodegradable aliphatic polyester,poly(w-pentadecalactone-co-ε-caprolactone)copolymer was synthesized via enzymatic ring-opening polymerization.A new biocatalyst,Candida antarctica lipase B,immobili...As an alternative biodegradable aliphatic polyester,poly(w-pentadecalactone-co-ε-caprolactone)copolymer was synthesized via enzymatic ring-opening polymerization.A new biocatalyst,Candida antarctica lipase B,immobilized onto rice husk ash was used for catalysis.Reactions were carried out at various temperatures and periods for varied copolymer compositions in order to obtain the highest molecular weight copolymer.The best reaction parameters were found to be 80℃ and 6 hours and molecular weights increased proportionally with the amount of w-pentadecalactone(w-PDL).The molecular structure of copolymer with 75%weight ratio of w-PDL(Mn=19720 g/mol)was characterized by proton and carbon nuclear magnetic resonance spectroscopies(^1H-NMR and ^13C-NMR).Thermal properties of the same copolymer and homopolymers were investigated by differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA).Improved thermal features were shown by addition of w-PDL to the structure and compared with poly(ε-caprolactone)(PCL).Consequently,poly(w-pentadecalactone-co-ε-caprolactone)copolymers were found to be good alternatives to widely used polyester,PCL,with their rapid polymerization tendency,higher molecular weights,and improved thermal features.展开更多
ABA triblock copolymers were synthesized by dihydroxyl-capped PEO initiated enzymatic ring-opening polymerization (eROP) of ε-CL in the presence of biocatalyst Novozyme 435. The chains ended with hydroxyl of ...ABA triblock copolymers were synthesized by dihydroxyl-capped PEO initiated enzymatic ring-opening polymerization (eROP) of ε-CL in the presence of biocatalyst Novozyme 435. The chains ended with hydroxyl of block copolymers were modified by the esterification of 2,2-dichloro acetyl chloride (DCAC) to obtain the tetrafunctional macroinitiator, which was used in the ATRP of 4-vinylpyridine (4-VP). CuCl/HMTETA was used as the catalyst system in the ATRP of 4-VP to acquire the H-shaped block copolymers (PVP)<sub>2</sub>-b-PCL-b-PEG-b-PCL-b-(PVP)<sub>2</sub>. The H-shaped block copolymers were characterized by FTIR, NMR, and GPC. Copolymers with high molecular weights (M <sub>n</sub> = 46121 g/mol) and low polydispersities (M <sub>w</sub>/M <sub>n</sub> = 1.30) were prepared. Moreover, the morphology of the copolymer was examined with dynamic light scattering (DLS) and atomic force microscopy (AFM). Spherical micelles with a diameter of 70 nm in aqueous solution were obtained.展开更多
用酶促开环聚合与ATRP方法相结合,制备了聚甲基丙烯酸六氟丁酯-聚己内酯-聚乙二醇-聚己内酯-聚甲基丙烯酸六氟丁酯(PHFMA-b-PCL-b-PEG-b-PCL-b-PHFMA)五嵌段聚合物.首先用Novozym e 435作为催化剂合成了聚己内酯-聚乙二醇-聚己内酯三嵌...用酶促开环聚合与ATRP方法相结合,制备了聚甲基丙烯酸六氟丁酯-聚己内酯-聚乙二醇-聚己内酯-聚甲基丙烯酸六氟丁酯(PHFMA-b-PCL-b-PEG-b-PCL-b-PHFMA)五嵌段聚合物.首先用Novozym e 435作为催化剂合成了聚己内酯-聚乙二醇-聚己内酯三嵌段聚合物,然后通过端基官能化法合成了大分子引发剂,并用其引发甲基丙烯酸六氟丁酯(HFMA)的ATRP反应,合成了五嵌段聚合物.通过核磁和GPC证明了大分子引发剂和五嵌段共聚物的结构,五嵌段共聚物的GPC分析表明这种合成方法的可行.共聚物胶束的直径和大小通过动态光散射方法和原子力显微镜测试,五嵌段共聚物在水中的的自组装行为也被研究.结果证明胶束是球形,其平均直径为77 nm.聚合物在四氢呋喃中的浓度对聚合物的聚集形貌有很大的影响.展开更多
采用新型化学酶法——开环易位聚合反应(ROMP)与酶促开环聚合反应(eROP)联用合成嵌段聚合物PCL-b-PB-b-PCL,用核磁共振氢谱(1 H NMR)、凝胶渗透色谱(GPC)和差示扫描量热法(DSC)表征产物的结构并进行性能测试.结果表明:GPC数据向高分子...采用新型化学酶法——开环易位聚合反应(ROMP)与酶促开环聚合反应(eROP)联用合成嵌段聚合物PCL-b-PB-b-PCL,用核磁共振氢谱(1 H NMR)、凝胶渗透色谱(GPC)和差示扫描量热法(DSC)表征产物的结构并进行性能测试.结果表明:GPC数据向高分子量移动,即成功合成了嵌段聚合物;嵌段聚合物可完全水解,且GPC数据向低分子量移动,表明该方法可行、有效.展开更多
基金The authors are grateful for the financial support of the National Natural Science Foundation of China (No. 20104005) and Hubei Province Natural Science Foundation of China (No. 2001B053) and a grant from National Key Fundamental Research Program of Chin
文摘Porcine pancreas lipase (PPL) and PPL immobilized on narrow distributed micron-sized glass beads wereemployed successfully for the ring-opening polymerization of 5, 5-dimethyl-1, 3-dioxan-2-one (DTC) for the first time.Different polymerization conditions such as enzyme concentration and reaction temperature were studied. Immobilized PPLexhibits higher activity than native PPL. Along wth the increasing enzyme concentration, the molecular weigh of resultingPDTC decreases. PPL immobilized on narrow distributed micron-sized glass beads has outstanding recyclability. For thethird recycle time, immobilized PPL exhibits the highest catalytic activity and with high activity even after the fifth recyletime for the synthesis of PDTC. The ~1H-NMR spectra indicate that decarboxylation does not occur during the ring-openingpolymerization.
文摘This work was directed to develop a novel method for the synthesis of hyperbranched polymers by combining enzymatic ring-opening polymerization(ROP) with self-condensing vinyl copolymerization(SCVCP). Functionalized PCL was prepared by ROP of ε-CL with HEMA as the initiator and catalyzed by Novozyme 435, and subsequently converted to AB* macroinimer by the esterification with 2-bromoisobutyryl bromide. The target polymer was obtained by SCVCP of AB* macroinimer with styrene via ATRP.
文摘Porcine pancreas lipase(PPL) immobilized on narrow distributed micron glass beads was employed successfully for ring-opening polymerization of ε-caprolactone(CL).Different polymerization conditions such as enzyme concentration,reaction temperature and reaction time were studied.The results showed that M_n of the resulting PCL was significantly increased compared with that catalyzed by PPL.Higher temperature and longer reaction time both contributed to gaining PCL with a higher molecular weight,while the yield had almost no change.In addition,for evaluating the recyclibilty of immobilized PPL on narrow distributed micron glass beads for the ring-opening polymerization of CL,we adopted the most severe reaction conditions(180 ℃,(240 h)) in the recycling experiments.It was found that the recovered immobilized PPL could be used again with a compatible high catalytic activity.The highest M_n of 21 300 of PCL could be obtained at a mass fraction of 5.18% of the reused immobilized PPL at 180 ℃ for 240 h,which is the highest M_n of PCL catalyzed by PPL.The excellent recyclability of immobilized PPL on narrow distributed micron glass beads is very helpful to its further industry applications.
文摘As an alternative biodegradable aliphatic polyester,poly(w-pentadecalactone-co-ε-caprolactone)copolymer was synthesized via enzymatic ring-opening polymerization.A new biocatalyst,Candida antarctica lipase B,immobilized onto rice husk ash was used for catalysis.Reactions were carried out at various temperatures and periods for varied copolymer compositions in order to obtain the highest molecular weight copolymer.The best reaction parameters were found to be 80℃ and 6 hours and molecular weights increased proportionally with the amount of w-pentadecalactone(w-PDL).The molecular structure of copolymer with 75%weight ratio of w-PDL(Mn=19720 g/mol)was characterized by proton and carbon nuclear magnetic resonance spectroscopies(^1H-NMR and ^13C-NMR).Thermal properties of the same copolymer and homopolymers were investigated by differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA).Improved thermal features were shown by addition of w-PDL to the structure and compared with poly(ε-caprolactone)(PCL).Consequently,poly(w-pentadecalactone-co-ε-caprolactone)copolymers were found to be good alternatives to widely used polyester,PCL,with their rapid polymerization tendency,higher molecular weights,and improved thermal features.
文摘ABA triblock copolymers were synthesized by dihydroxyl-capped PEO initiated enzymatic ring-opening polymerization (eROP) of ε-CL in the presence of biocatalyst Novozyme 435. The chains ended with hydroxyl of block copolymers were modified by the esterification of 2,2-dichloro acetyl chloride (DCAC) to obtain the tetrafunctional macroinitiator, which was used in the ATRP of 4-vinylpyridine (4-VP). CuCl/HMTETA was used as the catalyst system in the ATRP of 4-VP to acquire the H-shaped block copolymers (PVP)<sub>2</sub>-b-PCL-b-PEG-b-PCL-b-(PVP)<sub>2</sub>. The H-shaped block copolymers were characterized by FTIR, NMR, and GPC. Copolymers with high molecular weights (M <sub>n</sub> = 46121 g/mol) and low polydispersities (M <sub>w</sub>/M <sub>n</sub> = 1.30) were prepared. Moreover, the morphology of the copolymer was examined with dynamic light scattering (DLS) and atomic force microscopy (AFM). Spherical micelles with a diameter of 70 nm in aqueous solution were obtained.
文摘用酶促开环聚合与ATRP方法相结合,制备了聚甲基丙烯酸六氟丁酯-聚己内酯-聚乙二醇-聚己内酯-聚甲基丙烯酸六氟丁酯(PHFMA-b-PCL-b-PEG-b-PCL-b-PHFMA)五嵌段聚合物.首先用Novozym e 435作为催化剂合成了聚己内酯-聚乙二醇-聚己内酯三嵌段聚合物,然后通过端基官能化法合成了大分子引发剂,并用其引发甲基丙烯酸六氟丁酯(HFMA)的ATRP反应,合成了五嵌段聚合物.通过核磁和GPC证明了大分子引发剂和五嵌段共聚物的结构,五嵌段共聚物的GPC分析表明这种合成方法的可行.共聚物胶束的直径和大小通过动态光散射方法和原子力显微镜测试,五嵌段共聚物在水中的的自组装行为也被研究.结果证明胶束是球形,其平均直径为77 nm.聚合物在四氢呋喃中的浓度对聚合物的聚集形貌有很大的影响.
文摘采用新型化学酶法——开环易位聚合反应(ROMP)与酶促开环聚合反应(eROP)联用合成嵌段聚合物PCL-b-PB-b-PCL,用核磁共振氢谱(1 H NMR)、凝胶渗透色谱(GPC)和差示扫描量热法(DSC)表征产物的结构并进行性能测试.结果表明:GPC数据向高分子量移动,即成功合成了嵌段聚合物;嵌段聚合物可完全水解,且GPC数据向低分子量移动,表明该方法可行、有效.
