Preparation of non-conjugated luminescent polymers(NCLPs)with excellent cluster luminescence(CL)performance is of great significance for scientific and industrious applications,and yet improving the performance of NCL...Preparation of non-conjugated luminescent polymers(NCLPs)with excellent cluster luminescence(CL)performance is of great significance for scientific and industrious applications,and yet improving the performance of NCLPs through proper structural design is still a huge challenge.Herein,we report a non-conjugated ionized polymeric system consisting of(−)-camphorsulfonic acid((−)-CSA)and poly(2-vinylpyridine)(P2VP).These acid-base complexes exhibit typical excitationdependent fluorescence and room-temperature phosphorescence(RTP)with a lifetime up to 364 ms.We discover that changing the stereoregularity from atactic to isotactic significantly improves the CL performance of the complex.It(1)broadens the fluorescence emission spectra to cover the entire visible region,(2)enhances the fluorescence emission intensity at long wavelength beyond 500 nm,(3)enhances the phosphorescence intensity,and(4)extends the phosphorescence lifetime.Systematical experimental characterization and molecular dynamics simulation unravel the key role of stereoregularity in determining the formation of different pyridine aggregates that strongly influence the CL performance.Moreover,the different luminescence shows great potential in excitation divided information display and time-resolved encrypted display.This work not only points to a new direction for developing NCLPs with excellent performance,but also broadens the applications of NCLPs materials.展开更多
An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported. Isotacticity of poly（cyclohexene carbonate） （PCHC） has the critical influence ...An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported. Isotacticity of poly（cyclohexene carbonate） （PCHC） has the critical influence on the crystallinity, and only copolymers with a isotacticity of more than 90% are crystallizable. The stereoregular PCHC is a typical semi-crystalline thermoplastic, and possesses a high melting point （Tin） of 215-230℃ and a decomposition temperature of ca. 310℃. The spherulitic morphology of （R）-PCHC grows in a clockwise spiral from a center, and that of （S）-PCHC is a counterclockwise spiral, while the stereocomplex of （S）-PCHC/（R）-PCHC （1/1 mass ratio） presents lath-like dendritic crystal. The novel crystalline CO2-based polycarbonate represents a rare example of optically active polymers with unique crystallization behavior. Our findings reflect the critical influence of stereoregularity on the crystallization for this kind of polymeric materials, and may lead to developments of thermal-resistance CO2 copolymers for application in engineering thermoplastics.展开更多
Degradable polyesters have long been regarded as eco-friendly materials,useful for various applicationswhile meeting the growing needs of sustainability.However,it is still challenging to synthesize functional aliphat...Degradable polyesters have long been regarded as eco-friendly materials,useful for various applicationswhile meeting the growing needs of sustainability.However,it is still challenging to synthesize functional aliphatic polyesters from abundant and cheap renewable sources.Our present study reports a readily available and versatile platform for producing functional and stereoregular aliphatic polyesters from 4-hydroxy-L-proline(4-HYP).We synthesized a bicyclic bridged lactone monomer,namely,NR-PL,by a simple and scalable two-step process allowing facile side-chain functionalization and derivatization.The ring-opening homopolymerization and copolymerization for the generation of N^(R)-PL were controlled fully by using organobases such as 1,8-diazabicyclo[5.4.0]-undec-7-ene(DBU)without any detectable epimerization.This process afforded stereoregular polyesters PNRPE with molar mass(M_(n))up to 90 kg/mol and a narrow dispersity(Ð)generally below 1.10.The uniqueness of the backbone,which contains two chiral centers on a rigid propyl ring,together with the versatility of the side chain,offer tunable properties complementary to existing aliphatic polyesters.The utility of the polymers was showcased by the facile site-specific bioconjugation of PN^(EG3)PE,a water-soluble polyester,to a protein.This work might open numerous opportunities in creating functional and sustainable polyesters for a wide range of applications,including degradable plastics,drug delivery,and protein therapeutics.展开更多
Stereoselective polymerization can yield polymers with specific tacticity and properties,and it is an essential topic throughout polymer synthesis history.Herein,we report for the first time on a vesicular catalysis m...Stereoselective polymerization can yield polymers with specific tacticity and properties,and it is an essential topic throughout polymer synthesis history.Herein,we report for the first time on a vesicular catalysis method to realize the green stereoregular polymerization of isotactic-rich poly(methyl methacrylate)(PMMA)in water and at ambient temperature and pressure,namely by conducting the polymerization of MMA monomers in the confined 5-10 nm thick hydrophobic layers of hyperbranched polymer vesicles.The isotactic degree of the as-prepared PMMAs increases from 12% to 40% with the decrease of vesicle size from 840 to 85 nm in hydrodynamic diameter(Dh)due to the conformation confinement effect of MMA monomers inside the thin vesicle membranes through a curvature-dependent way.The present work has extended the scope of green chemistry,and it also represents a new application of polymer vesicles in stereoregular polymerization.展开更多
用溶剂热法制备无皂聚甲基丙烯酸甲酯(PMMA)纳米粒子,讨论了温度和丙酮含量对粒子粒径和分散度的影响,用DTA, 1HNMR, TEM, GPC等对产物进行了表征。结果表明无皂PMMA纳米粒子的粒径约60nm,分子量分布较好、以间同结构为主;随着反应温度...用溶剂热法制备无皂聚甲基丙烯酸甲酯(PMMA)纳米粒子,讨论了温度和丙酮含量对粒子粒径和分散度的影响,用DTA, 1HNMR, TEM, GPC等对产物进行了表征。结果表明无皂PMMA纳米粒子的粒径约60nm,分子量分布较好、以间同结构为主;随着反应温度增高,PMMA的玻璃化温度增加,间同结构含量有所增大,纳米粒子的粒径逐渐减小,粒径分布变差;溶剂中丙酮含量增加时,粒径逐渐减小,粒径的分布变差。展开更多
Polymerization of isobutyl vinyl ether(IBVE)has been studied with mononuclear half-titanocene,CpTiCl_3[1]and dinuclear half-titanocenes,[(C_5H_4)_2(CH_2)_n][(TiCl_3)_2][2(n=3),3(n=6)],and[(C_5H_4)_2(CH_2)_n[(TiCl_2OR_...Polymerization of isobutyl vinyl ether(IBVE)has been studied with mononuclear half-titanocene,CpTiCl_3[1]and dinuclear half-titanocenes,[(C_5H_4)_2(CH_2)_n][(TiCl_3)_2][2(n=3),3(n=6)],and[(C_5H_4)_2(CH_2)_n[(TiCl_2OR_2](R=2,6- diisopropylphenoxyl)[4(n=3),5(n=6)],in the presence of methyl aluminoxanes(MAO)as cocatalyst in methylene chloride.The influences of the length of polymethylene brigde and the substitution of aryloxy group at the metal center have been investigated at three polymerization temperature(...展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:51833001,51921002。
文摘Preparation of non-conjugated luminescent polymers(NCLPs)with excellent cluster luminescence(CL)performance is of great significance for scientific and industrious applications,and yet improving the performance of NCLPs through proper structural design is still a huge challenge.Herein,we report a non-conjugated ionized polymeric system consisting of(−)-camphorsulfonic acid((−)-CSA)and poly(2-vinylpyridine)(P2VP).These acid-base complexes exhibit typical excitationdependent fluorescence and room-temperature phosphorescence(RTP)with a lifetime up to 364 ms.We discover that changing the stereoregularity from atactic to isotactic significantly improves the CL performance of the complex.It(1)broadens the fluorescence emission spectra to cover the entire visible region,(2)enhances the fluorescence emission intensity at long wavelength beyond 500 nm,(3)enhances the phosphorescence intensity,and(4)extends the phosphorescence lifetime.Systematical experimental characterization and molecular dynamics simulation unravel the key role of stereoregularity in determining the formation of different pyridine aggregates that strongly influence the CL performance.Moreover,the different luminescence shows great potential in excitation divided information display and time-resolved encrypted display.This work not only points to a new direction for developing NCLPs with excellent performance,but also broadens the applications of NCLPs materials.
基金supported by the National Natural Science Foundation of China(Nos.21134002 and 21104003)National Basic Research Program of China(973 Program:2009CB825300)
文摘An example of crystalline CO2-based polymer from the asymmetric alternating copolymerization of CO2 and cyclohexene oxide is reported. Isotacticity of poly（cyclohexene carbonate） （PCHC） has the critical influence on the crystallinity, and only copolymers with a isotacticity of more than 90% are crystallizable. The stereoregular PCHC is a typical semi-crystalline thermoplastic, and possesses a high melting point （Tin） of 215-230℃ and a decomposition temperature of ca. 310℃. The spherulitic morphology of （R）-PCHC grows in a clockwise spiral from a center, and that of （S）-PCHC is a counterclockwise spiral, while the stereocomplex of （S）-PCHC/（R）-PCHC （1/1 mass ratio） presents lath-like dendritic crystal. The novel crystalline CO2-based polycarbonate represents a rare example of optically active polymers with unique crystallization behavior. Our findings reflect the critical influence of stereoregularity on the crystallization for this kind of polymeric materials, and may lead to developments of thermal-resistance CO2 copolymers for application in engineering thermoplastics.
基金National Natural Science Foundation of China(21722401 for H.Lu and 21634001 for E.Q.Chen).
文摘Degradable polyesters have long been regarded as eco-friendly materials,useful for various applicationswhile meeting the growing needs of sustainability.However,it is still challenging to synthesize functional aliphatic polyesters from abundant and cheap renewable sources.Our present study reports a readily available and versatile platform for producing functional and stereoregular aliphatic polyesters from 4-hydroxy-L-proline(4-HYP).We synthesized a bicyclic bridged lactone monomer,namely,NR-PL,by a simple and scalable two-step process allowing facile side-chain functionalization and derivatization.The ring-opening homopolymerization and copolymerization for the generation of N^(R)-PL were controlled fully by using organobases such as 1,8-diazabicyclo[5.4.0]-undec-7-ene(DBU)without any detectable epimerization.This process afforded stereoregular polyesters PNRPE with molar mass(M_(n))up to 90 kg/mol and a narrow dispersity(Ð)generally below 1.10.The uniqueness of the backbone,which contains two chiral centers on a rigid propyl ring,together with the versatility of the side chain,offer tunable properties complementary to existing aliphatic polyesters.The utility of the polymers was showcased by the facile site-specific bioconjugation of PN^(EG3)PE,a water-soluble polyester,to a protein.This work might open numerous opportunities in creating functional and sustainable polyesters for a wide range of applications,including degradable plastics,drug delivery,and protein therapeutics.
基金financially supported by the National Natural Science Foundation of China(21890730,21890733,and 51773115)the Program for Basic Research of Shanghai Science and Technology Commission(19JC1410400).
文摘Stereoselective polymerization can yield polymers with specific tacticity and properties,and it is an essential topic throughout polymer synthesis history.Herein,we report for the first time on a vesicular catalysis method to realize the green stereoregular polymerization of isotactic-rich poly(methyl methacrylate)(PMMA)in water and at ambient temperature and pressure,namely by conducting the polymerization of MMA monomers in the confined 5-10 nm thick hydrophobic layers of hyperbranched polymer vesicles.The isotactic degree of the as-prepared PMMAs increases from 12% to 40% with the decrease of vesicle size from 840 to 85 nm in hydrodynamic diameter(Dh)due to the conformation confinement effect of MMA monomers inside the thin vesicle membranes through a curvature-dependent way.The present work has extended the scope of green chemistry,and it also represents a new application of polymer vesicles in stereoregular polymerization.
文摘用溶剂热法制备无皂聚甲基丙烯酸甲酯(PMMA)纳米粒子,讨论了温度和丙酮含量对粒子粒径和分散度的影响,用DTA, 1HNMR, TEM, GPC等对产物进行了表征。结果表明无皂PMMA纳米粒子的粒径约60nm,分子量分布较好、以间同结构为主;随着反应温度增高,PMMA的玻璃化温度增加,间同结构含量有所增大,纳米粒子的粒径逐渐减小,粒径分布变差;溶剂中丙酮含量增加时,粒径逐渐减小,粒径的分布变差。
基金the Korea Ministry of Commerce,Industry,and Energy(Grant RTI04-01-04,Regional Technology Innovation Program).
文摘Polymerization of isobutyl vinyl ether(IBVE)has been studied with mononuclear half-titanocene,CpTiCl_3[1]and dinuclear half-titanocenes,[(C_5H_4)_2(CH_2)_n][(TiCl_3)_2][2(n=3),3(n=6)],and[(C_5H_4)_2(CH_2)_n[(TiCl_2OR_2](R=2,6- diisopropylphenoxyl)[4(n=3),5(n=6)],in the presence of methyl aluminoxanes(MAO)as cocatalyst in methylene chloride.The influences of the length of polymethylene brigde and the substitution of aryloxy group at the metal center have been investigated at three polymerization temperature(...
