In this study,a novel iron-based catalyst system,Fe(acac)3/(isocyanoimino)triptenylphosphorane(IITP)/AlR3,was employed for the synthesis of syndiotactic 1,2-polybutadiene in hexane.This catalyst system exhibits remark...In this study,a novel iron-based catalyst system,Fe(acac)3/(isocyanoimino)triptenylphosphorane(IITP)/AlR3,was employed for the synthesis of syndiotactic 1,2-polybutadiene in hexane.This catalyst system exhibits remarkably high catalytic activity,achieving a polymerization activity of 762 kgpolymer·molcatalyst^(-1)·h^(-1)at 50℃with a[BD]/[Fe]molar ratio of 20000.Furthermore,living polymerization characteristic were observed during the investigation of the polymerization kinetics of 1,3-butadiene polymerization.These characteristics were well demonstrated by a narrow molecular weight distribution(PDI≈2.0)of the resulting polybutadiene and a linear relationship between-ln(1-c)and polymerization time as well as number average molecular weight and polymer yield.The resultant polymer showed a 1,2-selectivity of approximately 76%and stereoregularity ranging from 62%to 73%(rrrr).Additionally,through kinetic studies on polymerization reaction,an apparent activation energy Ea value of this catalytic system was calculated to be 84.98 kJ·mol^(-1),which suggests that high polymerization temperature favors efficient polymerization.展开更多
Through neodymium-mediated coordinative chain transfer copolymerizaiton(CCTcoP),polyisoprenes bearing dual hydroxylated mini-blocky chain-ends were prepared via a three-step strategy.Kinetic studies revealed that,the ...Through neodymium-mediated coordinative chain transfer copolymerizaiton(CCTcoP),polyisoprenes bearing dual hydroxylated mini-blocky chain-ends were prepared via a three-step strategy.Kinetic studies revealed that,the polymerization demonstrated typical features of CCTcoP across the whole polymerization process,i.e.,quasi-living polymerization characteristic,tunable molecular weights,narrow molecular weight distributions,and atom economies.Comparing to previously reported CCTP homopolymerization systems,the presence of oxygen-containing IpOAl polar comonomer slowed down chain transfer rates obviously,rendering slightly higher molecular weights of the resultant PIps and smaller Np(number of polymer chains per Nd atom)values.Moreover,to mimic the structure of natural rubber,the hydroxyl end groups can be facilely modified into phosphonate,amide,and UPy,whose structures were further confirmed by NMR spectra.Incorporation these functionalities could greatly improve the hydrophilic properties of the polymers,as revealed from the significantly reduced static water contact angles.展开更多
Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers t...Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers their further detailed characterizations,such as molecular weights,polydispersities,stereoregularities,etc.In this work,we surprisingly found that for a traditional Ni(acac)_(2)/MAO system that was previously reported to give insoluble PNBs,incorporation of highly bulk salicylaldiminate ligands could significantly improve the solubility of the PNBs in common organic solvents,which allowed for subsequent thorough detailed analysis of the polymer products.Moreover,it was also observed that high-temperature polymerization was beneficial for further improving the PNB’s solubilities due to the decreased molecular weights and stereoregularities.Different ligand skeletons and ligand equivalents were also investigated to give a comprehensive view of their influences on the polymers’solubilities,and based on these results,a plausible mechanism that caused such a big difference was tentatively proposed.展开更多
Three types of organic compounds--two carboxylic acids and an anhydride, were used as additives for polyketone （PK）. The effect of the additive structure and their feed ratios on the melting temperature, crystalliza...Three types of organic compounds--two carboxylic acids and an anhydride, were used as additives for polyketone （PK）. The effect of the additive structure and their feed ratios on the melting temperature, crystallization temperature, and crystallization rate of PK were studied. We found that the crystallization temperature could be reduced significantly by introducing a small quantity of organic additive, in particular, an anhydride. On addition of 1 phr of anhydride, the crystallization temperature was reduced by 10.7 ℃. Therefore, the non-isothermal crystallization kinetics of aliphatic PKJanhydride blends with various feed ratios was investigated using DSC. The results were analyzed by various theoretical models, such as Avrami, Ozawa and combined Avrami-Ozawa models.展开更多
A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of(PhC=N(C_6H_3(R_1)2-2,6)(C_3 HN_2(R_2)2-3,5)MtCl_2(R_1 = Me, R_2 = H, Mt = Co(1 a), Fe(2 a); R_1 = Me, R_2 = Me, Mt = Co(1b), Fe(2b...A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of(PhC=N(C_6H_3(R_1)2-2,6)(C_3 HN_2(R_2)2-3,5)MtCl_2(R_1 = Me, R_2 = H, Mt = Co(1 a), Fe(2 a); R_1 = Me, R_2 = Me, Mt = Co(1b), Fe(2b); R_1 = iPr, R_2 = H, Mt = Co(1 c), Fe(2 c); R_1 = i Pr, R_2 = Me, Mt = Co(1 d), Fe(2 d); R_1 = i Pr, R_2 = Ph, Mt = Co(1 e), Fe(2 e)) were synthesized and thoroughly characterized.Determined by single crystal X-ray diffraction, complexes 1 b and 2 b revealed dimeric structures, in which distorted trigonal bipyramid geometries were adopted for each metal centers. In the presence of ethylaluminum sesquichloride(EASC), all the cobalt complexes displayed high activities in 1,3-butadiene polymerization, affording polybutadienes with predominant cis-1,4 contents(up to 97.0%).Influences of ligand structure and polymerization parameters on catalytic performance were investigated systematically. For pyrazolylimine iron(II) dichloride complexes, the catalytic activities and microstructures of the resultant polybutadienes were highly dependent on ligand structures and polymerization conditions. For complex 2 a, changing cocatalyst from trialkyl aluminums to methyl aluminoxane(MAO) led to an shift of selectivity from high cis-1,4-to trans-1,4-/1,2-manner. Being activated by MAO, complexes 2 a and 2 b gave trans-1,4-/1,2-binary polybutadienes, while complexes 2 c, 2 d, and 2 e afforded cis-1,4-enriched polymers.展开更多
A series of mono-and binuclear Co（Ⅱ） complexes （Col-Co7） supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized. Measured by single crystal X-ray crystallography, complexes Col and...A series of mono-and binuclear Co（Ⅱ） complexes （Col-Co7） supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized. Measured by single crystal X-ray crystallography, complexes Col and Co3 adopted distorted tetrahedral structures around the cobalt center. Upon activation by ethylaluminium sesquichloride （EASC）, these cobalt complexes exhibited high catalytic activity and cis-l,4-selectivity towards 1,3-butadiene polymerization. The effects of ligand environment, polymerization temperature, and cocatalyst types on the polymerization were investigated in detail. Interestingly, the binuclear Co（Ⅱ） complexes exhibited high thermal stability, and the polymer yields were up to 97.2% even at a high temperature of 70 ℃.展开更多
The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high act...The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high activity and controllable selectivity. The microstructure of the resultant polymer was adjustable by variation of electron donor and/or the alkylaluminum. ^13C-NMR and thermal analysis demonstrate that the produced polybutadienes have stereo-block chain structures of cis-1,4 and trans-1,4 segments with adjustable Tm and To. The neodymium sulfonate-based catalyst is believed to be significant in regulating the chain structure of polydienes and in exploring 1,3-diene polymerization mechanism.展开更多
A family of highly bulky bis(salicylaldiminate)Co(Ⅱ)complexes bearing cavity-like conformations are disclosed herein.Due to their unique bulky nature around the cobalt atoms that are reflected from space-filling mode...A family of highly bulky bis(salicylaldiminate)Co(Ⅱ)complexes bearing cavity-like conformations are disclosed herein.Due to their unique bulky nature around the cobalt atoms that are reflected from space-filling models and the buried volume percentages,obviously longer bond distances of Co―N and Co―O are revealed from those complexes.Moreover,because of these well-protected active species,the cobalt complexes are able to catalyze 1,3-butadiene polymerization in high yields at extreme low catalyst concentrations,revealing a ultra high catalytic efficiency.At a ratio of 50000,all the complexes can afford polybutadiene with yields higher than 90%.Furthermore,the highly steric bulkiness of the ligand can also significantly enhance the thermostability of the active species.At temperature of 80-120°C,the complexes are able to successfully maintain high activities,giving polymer yields up to 90%.展开更多
基金This work was financially supported by the National Key R&D Program of China(No.2022YFB3704700).
文摘In this study,a novel iron-based catalyst system,Fe(acac)3/(isocyanoimino)triptenylphosphorane(IITP)/AlR3,was employed for the synthesis of syndiotactic 1,2-polybutadiene in hexane.This catalyst system exhibits remarkably high catalytic activity,achieving a polymerization activity of 762 kgpolymer·molcatalyst^(-1)·h^(-1)at 50℃with a[BD]/[Fe]molar ratio of 20000.Furthermore,living polymerization characteristic were observed during the investigation of the polymerization kinetics of 1,3-butadiene polymerization.These characteristics were well demonstrated by a narrow molecular weight distribution(PDI≈2.0)of the resulting polybutadiene and a linear relationship between-ln(1-c)and polymerization time as well as number average molecular weight and polymer yield.The resultant polymer showed a 1,2-selectivity of approximately 76%and stereoregularity ranging from 62%to 73%(rrrr).Additionally,through kinetic studies on polymerization reaction,an apparent activation energy Ea value of this catalytic system was calculated to be 84.98 kJ·mol^(-1),which suggests that high polymerization temperature favors efficient polymerization.
基金financially supported by the National Natural Science Foundation of China(No.U1862206)Jilin Province Department of Education(No.JJKH20200665KJ)+3 种基金Dr.W.Zhao thanks for the financial support from China Postdoctoral Science Foundation(No.2021M701818)Shandong Provincial Natural Science Foundation,China(No.ZR2022QE237)Qingdao Postdoctoral Applied Research Project,PetroChina Company Limited(No.2020B-2711)H.Liu sincerely acknowledges the financial support from the Taishan Scholars Program。
文摘Through neodymium-mediated coordinative chain transfer copolymerizaiton(CCTcoP),polyisoprenes bearing dual hydroxylated mini-blocky chain-ends were prepared via a three-step strategy.Kinetic studies revealed that,the polymerization demonstrated typical features of CCTcoP across the whole polymerization process,i.e.,quasi-living polymerization characteristic,tunable molecular weights,narrow molecular weight distributions,and atom economies.Comparing to previously reported CCTP homopolymerization systems,the presence of oxygen-containing IpOAl polar comonomer slowed down chain transfer rates obviously,rendering slightly higher molecular weights of the resultant PIps and smaller Np(number of polymer chains per Nd atom)values.Moreover,to mimic the structure of natural rubber,the hydroxyl end groups can be facilely modified into phosphonate,amide,and UPy,whose structures were further confirmed by NMR spectra.Incorporation these functionalities could greatly improve the hydrophilic properties of the polymers,as revealed from the significantly reduced static water contact angles.
基金financially supported by the National Natural Science Foundation of China(Nos.21801236 and U1862206)。
文摘Late transition metals have long served as workhorses for vinyl polymerization of norbornene derivatives.Nevertheless,for such catalytic systems,insoluble polynorbornene(PNB)products are often produced which hampers their further detailed characterizations,such as molecular weights,polydispersities,stereoregularities,etc.In this work,we surprisingly found that for a traditional Ni(acac)_(2)/MAO system that was previously reported to give insoluble PNBs,incorporation of highly bulk salicylaldiminate ligands could significantly improve the solubility of the PNBs in common organic solvents,which allowed for subsequent thorough detailed analysis of the polymer products.Moreover,it was also observed that high-temperature polymerization was beneficial for further improving the PNB’s solubilities due to the decreased molecular weights and stereoregularities.Different ligand skeletons and ligand equivalents were also investigated to give a comprehensive view of their influences on the polymers’solubilities,and based on these results,a plausible mechanism that caused such a big difference was tentatively proposed.
文摘Three types of organic compounds--two carboxylic acids and an anhydride, were used as additives for polyketone （PK）. The effect of the additive structure and their feed ratios on the melting temperature, crystallization temperature, and crystallization rate of PK were studied. We found that the crystallization temperature could be reduced significantly by introducing a small quantity of organic additive, in particular, an anhydride. On addition of 1 phr of anhydride, the crystallization temperature was reduced by 10.7 ℃. Therefore, the non-isothermal crystallization kinetics of aliphatic PKJanhydride blends with various feed ratios was investigated using DSC. The results were analyzed by various theoretical models, such as Avrami, Ozawa and combined Avrami-Ozawa models.
基金financially supported by the National Basic Research Program of China(No.2015CB654700(2015CB654702))the National Natural Science Foundation of China(No.21801236)
文摘A series of pyrazolylimine ligated Co(II) and Fe(II) complexes with general formula of(PhC=N(C_6H_3(R_1)2-2,6)(C_3 HN_2(R_2)2-3,5)MtCl_2(R_1 = Me, R_2 = H, Mt = Co(1 a), Fe(2 a); R_1 = Me, R_2 = Me, Mt = Co(1b), Fe(2b); R_1 = iPr, R_2 = H, Mt = Co(1 c), Fe(2 c); R_1 = i Pr, R_2 = Me, Mt = Co(1 d), Fe(2 d); R_1 = i Pr, R_2 = Ph, Mt = Co(1 e), Fe(2 e)) were synthesized and thoroughly characterized.Determined by single crystal X-ray diffraction, complexes 1 b and 2 b revealed dimeric structures, in which distorted trigonal bipyramid geometries were adopted for each metal centers. In the presence of ethylaluminum sesquichloride(EASC), all the cobalt complexes displayed high activities in 1,3-butadiene polymerization, affording polybutadienes with predominant cis-1,4 contents(up to 97.0%).Influences of ligand structure and polymerization parameters on catalytic performance were investigated systematically. For pyrazolylimine iron(II) dichloride complexes, the catalytic activities and microstructures of the resultant polybutadienes were highly dependent on ligand structures and polymerization conditions. For complex 2 a, changing cocatalyst from trialkyl aluminums to methyl aluminoxane(MAO) led to an shift of selectivity from high cis-1,4-to trans-1,4-/1,2-manner. Being activated by MAO, complexes 2 a and 2 b gave trans-1,4-/1,2-binary polybutadienes, while complexes 2 c, 2 d, and 2 e afforded cis-1,4-enriched polymers.
基金financially supported by the National Key R&D Program of China (No.2017YFB0307100 (2017YFB0307103))National Basic Research Program of China (No.2015CB654700 (2015CB654702))
文摘A series of mono-and binuclear Co（Ⅱ） complexes （Col-Co7） supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized. Measured by single crystal X-ray crystallography, complexes Col and Co3 adopted distorted tetrahedral structures around the cobalt center. Upon activation by ethylaluminium sesquichloride （EASC）, these cobalt complexes exhibited high catalytic activity and cis-l,4-selectivity towards 1,3-butadiene polymerization. The effects of ligand environment, polymerization temperature, and cocatalyst types on the polymerization were investigated in detail. Interestingly, the binuclear Co（Ⅱ） complexes exhibited high thermal stability, and the polymer yields were up to 97.2% even at a high temperature of 70 ℃.
基金financially supported by the National Basic Research Program of China(No.2015CB654700(2015CB674702))The CAS Hundred Talents Program(Y220011001)+1 种基金the National Natural Science Foundation of China(Nos.51473156 and 51203147)Jilin Provincial Research Fund for Basic Research,China(No.20130102007JC)
文摘The polymerization of 1,3-butadiene was examined by using a novel halogen-free neodymium m-nitrobenzenesulfonate （Nd（3-NBSOa）3·donors）/alkylaluminum binary catalyst system. The catalyst showed fairly high activity and controllable selectivity. The microstructure of the resultant polymer was adjustable by variation of electron donor and/or the alkylaluminum. ^13C-NMR and thermal analysis demonstrate that the produced polybutadienes have stereo-block chain structures of cis-1,4 and trans-1,4 segments with adjustable Tm and To. The neodymium sulfonate-based catalyst is believed to be significant in regulating the chain structure of polydienes and in exploring 1,3-diene polymerization mechanism.
基金financially supported by the National Natural Science Foundation of China(Nos.U1862206 and 21801236)。
文摘A family of highly bulky bis(salicylaldiminate)Co(Ⅱ)complexes bearing cavity-like conformations are disclosed herein.Due to their unique bulky nature around the cobalt atoms that are reflected from space-filling models and the buried volume percentages,obviously longer bond distances of Co―N and Co―O are revealed from those complexes.Moreover,because of these well-protected active species,the cobalt complexes are able to catalyze 1,3-butadiene polymerization in high yields at extreme low catalyst concentrations,revealing a ultra high catalytic efficiency.At a ratio of 50000,all the complexes can afford polybutadiene with yields higher than 90%.Furthermore,the highly steric bulkiness of the ligand can also significantly enhance the thermostability of the active species.At temperature of 80-120°C,the complexes are able to successfully maintain high activities,giving polymer yields up to 90%.
