The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with V...The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.展开更多
i-PP/m-EPR reactor alloy were prepared through ethylene/propylene slurry copolymerization catalyzed by metallocene(rac-Et(Ind)_2ZrCl_2)supported on porous iPP particles.Polar monomer(dihydromyrcene alcohol)treated wit...i-PP/m-EPR reactor alloy were prepared through ethylene/propylene slurry copolymerization catalyzed by metallocene(rac-Et(Ind)_2ZrCl_2)supported on porous iPP particles.Polar monomer(dihydromyrcene alcohol)treated with triethyaluminum was added in the preparation of porous iPP particles to introduce hydroxyl groups and thus enhance the ability for chemically supporting the metallocene catalyst.The effects of MAO/Zr ratio and monomer composition in feed on the reaction activity and property of polymer were i...展开更多
Copolymerization of propylene and hindered piperidine monomers was carried out over a high activity supported Ziegler-Natta catalyst, using Al(C2H5)(3) as cocatalyst. Factors which affect the copolymerization were stu...Copolymerization of propylene and hindered piperidine monomers was carried out over a high activity supported Ziegler-Natta catalyst, using Al(C2H5)(3) as cocatalyst. Factors which affect the copolymerization were studied, The copolymers exhibited high light stability without adding extra light stabilizers. A self-stabilized polypropylene was prepared.展开更多
(CpCH_2CH_2CH = CH_2)_2MCl_2(M=Zr, Hf)/MAO and Cp_2ZrCl_2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand an...(CpCH_2CH_2CH = CH_2)_2MCl_2(M=Zr, Hf)/MAO and Cp_2ZrCl_2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH_2CH_2CH=CH_2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6～8 times lower than that of the analogous zirconocene catalyst, ^(13)C NMR analysis showed that the copolymerobtained using the unsubstituted catalyst Cp_2ZrCl_2 has greater incorporatien of propene than those produced byCH_2CH_2CH=CH_2 substituted Zr and Hf catalysts. The melting point, crystallinity and the viscosity-average molecularweight of the copolymer decreased with an increase of propenc concentration in the feed. Both CH_2CH_2CH= CH_2 substitutedZr and Hf catalysts exhibit little or no difference in the melting point and crystallinity of the produced copolymers. However,there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp_2ZrCl_2 catalyst havemuch lower T_m and X_c than those obtained with the (CpCH_2CH_2CH=CH_2)_2ZrCl_2 catalyst. The density and molecular weightof the copolymer decreased in the order: (CpCH_2CH_2CH=CH_2)_2HfCl_2>(CpCH_2CH_2CH=CH_2)_2ZrCl_2>Cp_2ZrCl_2. The kineticbehavior of copolymerizaton with Hf catalyst was found to be different from that with Zr catalyst.展开更多
The impact propylene copolymer （IPC） and isotactic polypropylene （iPP） were separately selected to prepare laminates with high density polyethylene （HDPE） by hot press. The peel forces of IPC/HDPE and iPP/HDPE l...The impact propylene copolymer （IPC） and isotactic polypropylene （iPP） were separately selected to prepare laminates with high density polyethylene （HDPE） by hot press. The peel forces of IPC/HDPE and iPP/HDPE laminates were examined, and it was found that the welded joint strength in IPC/HDPE laminate was dramatically higher than that of iPP/HDPE laminate. According to the special microstructure of IPC, the co-crystallization of the ethylene segments in ethylene-propylene block copolymer （EbP） component of IPC and the PE chain in HDPE was proposed to explain the high- strength welding. The DSC results indicated that there indeed existed some interaction between IPC and HDPE, and the crystallizable PE component in IPC could affect the crystallization of HDPE. The scanning electron microscope （SEM） observations of IPC/HDPE blends demonstrated that HDPE tended to stay with the PE-rich EbP chains to form the dispersed phase, indicating the good miscibility between HDPE and EbP components of IPC. According to the above results, the effect of co-crystallization of the PE components of the IPC and HDPE on the high weld strength of IPC/HDPE laminate was confirmed.展开更多
In this work, the surface activity of block copolymer nonionic surfactants (RPE) has been determined, i.e., critical micelle concentration (CMC), surface excess concentration (Γ), surface area demand per molecule (A)...In this work, the surface activity of block copolymer nonionic surfactants (RPE) has been determined, i.e., critical micelle concentration (CMC), surface excess concentration (Γ), surface area demand per molecule (A), surface tension at CMC (γCMC). A linear decrease of ln[CMC] vs number of oxypropylene units in copolymer molecule was observed. The change in the work of cohesion per oxypropylene group when passing from molecular into micellar state, calculated from the Shinoda equation, was 0.43kT for the studied compounds.展开更多
Both terminated functional isotactic polypropylene （iPP） and block copolymers containing iPP segment are desirable for commercial applications. This paper provides a convenient, highly-efficient method to prepare hy...Both terminated functional isotactic polypropylene （iPP） and block copolymers containing iPP segment are desirable for commercial applications. This paper provides a convenient, highly-efficient method to prepare hydroxyl-terminated isotactic polypropylene （iPP-t-OH） and functional di-block copolymer containing the iPP segment through a combination of coordination polymerization and coupling reaction. The coordination polymerization was catalyzed by TiCI4/MgCI2/AIEt3 catalyst system using ZnEt2 as chain transfer agent. Further, the Zn-terminated iPP was oxidized and subsequently hydrolyzed to provide iPP-t-OH. Soxhlet extraction and 13C NMR were used to calculate the isotacticity of iPP-t-OH. The degree of polymerization and the number of hydroxyl groups at the chain end of iPP-t-OH were measured by GPC and 1H NMR. Despite the high molecular weight and heterogeneous reaction, iPP-t-OH is effectively linked with PEG-t-NCO to produce di-block copolymers. DSC analysis of the di-block copolymer shows an obvious decrease in Tm and To, which indicated that PEG was successfully linked to the terminal end of iPP.展开更多
基金financially supported by the National Natural Science Foundation of China (Nos.21774006 and 21634002)。
文摘The highly efficient method has been developed for the synthesis of NHC·VOCl_(3) containing symmetrical or unsymmetrical Nheterocyclic carbene(NHC) ligands by the transmetallation reaction of NHC·AgCl with VOCl_(3).The total isolated yield of VOCl_(3)[1,3-(2,4,6-Me_(3)C_(6)H_(2))_(2)(NCH=)_(2)C:](V4') reached 86% by transmetallation reaction,which is much higher than that(48%) by direct coordination method.This methodology has also been used to synthesize the novel vanadium complexes containing unsymmetrical NHC ligands of VOCl_(3)[PhCH_(2)NCH=CHNR)C:](V5',R=2,4,6-Me_(3)C_(6)H_(2);V6',R=2,4-Me_(2)-6-Ph-C_(6)H_(2);V7',R=2,6-^(i)Pr_(2)-C_(6)H_(3)) with high yield,which could not be obtained by direct coordination method.The catalytic activity and copolymerization ability would be improved by introducing unsymmetrical NHC ligands due to their less steric bulky effect.The vanadium complex V5' containing unsymmetrical NHC ligand exhibits higher catalytic activity(3.7×10^(5)g_(copolymer)·mol^(-1) of V·h^(-1)) than that of V4' containing symmetrical NHC ligand.Moreover,the higher propylene incorporation ratio(45.6 mol%) in the copolymers of ethylene with propylene could be obtained by using V5' than that(39.9%) by using V4'.The results would provide a highly efficient strategy for the synthesis of early transition metal complexes containing versitile NHC ligands,affording the catalyst with both high catalytic activity and copolymerization ability for the synthesis of high performance polyolefin elastomers.
基金National Basic Research Program of China(No.2005CB623804)the National Natural Science Foundation of China(No.20476090).
文摘i-PP/m-EPR reactor alloy were prepared through ethylene/propylene slurry copolymerization catalyzed by metallocene(rac-Et(Ind)_2ZrCl_2)supported on porous iPP particles.Polar monomer(dihydromyrcene alcohol)treated with triethyaluminum was added in the preparation of porous iPP particles to introduce hydroxyl groups and thus enhance the ability for chemically supporting the metallocene catalyst.The effects of MAO/Zr ratio and monomer composition in feed on the reaction activity and property of polymer were i...
文摘Copolymerization of propylene and hindered piperidine monomers was carried out over a high activity supported Ziegler-Natta catalyst, using Al(C2H5)(3) as cocatalyst. Factors which affect the copolymerization were studied, The copolymers exhibited high light stability without adding extra light stabilizers. A self-stabilized polypropylene was prepared.
文摘(CpCH_2CH_2CH = CH_2)_2MCl_2(M=Zr, Hf)/MAO and Cp_2ZrCl_2/MAO (Cp=cyclopentadienyl; MAO=methylaluminoxane) catalyst systems have been compared for ethylene copolymerization to investigate the influence of theligand and transition metal on the polymerization activity and copolymer properties. For both CH_2CH_2CH=CH_2 substitutedcatalysts the catalytic activity decreased with increasing propene concentration in the feed. The activity of the hafnocenecatalyst was 6～8 times lower than that of the analogous zirconocene catalyst, ^(13)C NMR analysis showed that the copolymerobtained using the unsubstituted catalyst Cp_2ZrCl_2 has greater incorporatien of propene than those produced byCH_2CH_2CH=CH_2 substituted Zr and Hf catalysts. The melting point, crystallinity and the viscosity-average molecularweight of the copolymer decreased with an increase of propenc concentration in the feed. Both CH_2CH_2CH= CH_2 substitutedZr and Hf catalysts exhibit little or no difference in the melting point and crystallinity of the produced copolymers. However,there are significant differences between the two zirconocene catalysts. The copolymer produced by Cp_2ZrCl_2 catalyst havemuch lower T_m and X_c than those obtained with the (CpCH_2CH_2CH=CH_2)_2ZrCl_2 catalyst. The density and molecular weightof the copolymer decreased in the order: (CpCH_2CH_2CH=CH_2)_2HfCl_2>(CpCH_2CH_2CH=CH_2)_2ZrCl_2>Cp_2ZrCl_2. The kineticbehavior of copolymerizaton with Hf catalyst was found to be different from that with Zr catalyst.
基金supported by the National Basic Research Program of China(No.2005CB623800)the National Natural Science Foundation of China(No.50603023)the Joint Research Fund for Overseas Chinese Young Scholars (No.50728302)
文摘The impact propylene copolymer （IPC） and isotactic polypropylene （iPP） were separately selected to prepare laminates with high density polyethylene （HDPE） by hot press. The peel forces of IPC/HDPE and iPP/HDPE laminates were examined, and it was found that the welded joint strength in IPC/HDPE laminate was dramatically higher than that of iPP/HDPE laminate. According to the special microstructure of IPC, the co-crystallization of the ethylene segments in ethylene-propylene block copolymer （EbP） component of IPC and the PE chain in HDPE was proposed to explain the high- strength welding. The DSC results indicated that there indeed existed some interaction between IPC and HDPE, and the crystallizable PE component in IPC could affect the crystallization of HDPE. The scanning electron microscope （SEM） observations of IPC/HDPE blends demonstrated that HDPE tended to stay with the PE-rich EbP chains to form the dispersed phase, indicating the good miscibility between HDPE and EbP components of IPC. According to the above results, the effect of co-crystallization of the PE components of the IPC and HDPE on the high weld strength of IPC/HDPE laminate was confirmed.
基金Project (No. 2004C31058) supported by the Zhejiang ProvincialS&T Programme of China
文摘In this work, the surface activity of block copolymer nonionic surfactants (RPE) has been determined, i.e., critical micelle concentration (CMC), surface excess concentration (Γ), surface area demand per molecule (A), surface tension at CMC (γCMC). A linear decrease of ln[CMC] vs number of oxypropylene units in copolymer molecule was observed. The change in the work of cohesion per oxypropylene group when passing from molecular into micellar state, calculated from the Shinoda equation, was 0.43kT for the studied compounds.
基金supported by the National Natural Science Foundation of China(No.51173157)National High-Tech R&D Program of China(No.2012AA040305)the Major State Basic Research Programs(No.2011CB606001)
文摘Both terminated functional isotactic polypropylene （iPP） and block copolymers containing iPP segment are desirable for commercial applications. This paper provides a convenient, highly-efficient method to prepare hydroxyl-terminated isotactic polypropylene （iPP-t-OH） and functional di-block copolymer containing the iPP segment through a combination of coordination polymerization and coupling reaction. The coordination polymerization was catalyzed by TiCI4/MgCI2/AIEt3 catalyst system using ZnEt2 as chain transfer agent. Further, the Zn-terminated iPP was oxidized and subsequently hydrolyzed to provide iPP-t-OH. Soxhlet extraction and 13C NMR were used to calculate the isotacticity of iPP-t-OH. The degree of polymerization and the number of hydroxyl groups at the chain end of iPP-t-OH were measured by GPC and 1H NMR. Despite the high molecular weight and heterogeneous reaction, iPP-t-OH is effectively linked with PEG-t-NCO to produce di-block copolymers. DSC analysis of the di-block copolymer shows an obvious decrease in Tm and To, which indicated that PEG was successfully linked to the terminal end of iPP.
