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Synthesis of Ultra-High-Molecular-Weight Polyethylene by Transition-Metal-Catalyzed Precipitation Polymerization

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Precision Chemistry

Precision Chemistry 2024年第2期2卷 63-69页

作者： Wenbing Wang Quan Wang Chen Zou Changle Chen Key Laboratory of Precision and Intelligent Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China

Ultra-high-molecular-weight polyethylene(UHMWPE)plays an important role in many important fields as engineering plastics.In this contribution,a precipitation polymerization strategy is developed by combination of highly active phosphino-phenolate nickel catalysts with polymer-insoluble solvent(heptane)to access UHMWPE(Mn up to 8.3×10^(6)g mol^(-1))with good product morphology,free-flowing characteristics,and great mechanical properties.Compared with the academically commonly used aromatic solvent(toluene),the utilization of heptane offers simultaneous enhancement in important parameters including activity,polymer molecular weight,and catalyst thermal stability.This system can also generate polar functionalized UHMWPE with molecular weight of up to 1.6×10^(6)g mol^(-1)in the copolymerization of ethylene with polar comonomers.More importantly,this precipitation polymerization strategy is generally applicable to several representative transition metal catalyst systems,leading to UHMWPE synthesis with good product morphology control.

关键词： transition metal catalysts polyolefin UHMWPE precipitation polymerization polar monomer

A“Catalyst+Support”Strategy for Salicylaldimine Nickel Catalyzed Ethylene Polymerization and Copolymerization with polar monomers

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Chemical Research in Chinese Universities 2023年第5期39卷 726-730页

作者： WANG Zihao YANG Lei XU Mengli TAN Chen CHEN Changle Key Laboratory of Precision and Intelligent Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026P.R.China Institutes of Physical Science and Information Technology Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of EducationKey Laboratory of Environment-Friendly Polymeric Materials of Anhui ProvinceAnhui UniversityHefei 230601P.R.China School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003P.R.China

Polyolefins,as one of the most productive synthetic polymer materials,have been widely used in industry and daily life[1-2].However,due to their"non-polar"nature,polyolefins have poor compatibility and adhesion to pol... 详细信息

关键词： Nickel Salicylaldimine polar monomer Polyolefin Heterogeneous

Photoresponsive α-Diimine Nickel Modulated Ethylene (Co)Polymerization

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Chinese Journal of Chemistry 2022年第24期40卷 2919-2926页

作者： Jingshuang Yang Xiaoqiang Hu Zhongbao Jian State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesRenmin Street 5625ChangchunJilin130022 China University of Science and Technology of China HefeiAnhui230026 China

Beyond the single ligand electronic and/or steric modifications, external stimuli are a useful tool for modulating catalytic polymerization reactions. Light stands out from external stimuli, but the corresponding photoresponsive transition metal catalysts are significantly rare for olefin polymerization due to the difficult synthesis. In this contribution, in consideration of the key role of steric shielding on the axial sites, we installed four concerted azobenzene moieties into symmetrically terphenyl-based α-diimine Ni(II) complexes to prepare photoresponsive catalysts, which were applied to ethylene polymerization and copolymerization with polar monomer. Via the trans-cis isomerization of azobenzene-functionalized Ni(II) catalysts in dark or under UV light, catalytic activity, polymer molecular weight, branching density, incorporation of co-monomer, and even the ratio of branching pattern were significantly modulated in ethylene (co)polymerizations. This photo-controlled strategy behaved an opposite influence between ethylene polymerization and copolymerization, in terms of catalytic activity and polymer molecular weight. As a result, slightly branched ultrahigh molecular weight polyethylenes and high molecular weight functionalized polyethylenes were produced at ambient conditions.

关键词： Olefin polymerization Photochemistry Polyethylene polar monomer Nickel catalyst

Influence of Backbone and Axial Substituent of Catalyst onα-Imino-ketone Nickel Mediated Ethylene(Co)Polymerization

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Chinese Journal of Polymer Science 2022年第5期40卷 469-477页

作者： Yu-Kai Chu Xiao-Qiang Hu Yue Zhang Da-Jun Liu Yi-Xin Zhang Zhong-Bao Jian College of Chemistry and Environmental Engineering Changchun University of Science and TechnologyChangchun 130022China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 730022China

Theα-imino-ketone nickel catalyst is an emerging versatile platform that is easy to prepare and allows for the production of branched high molecular weight functionalized polyethylenes.However,study on this catalyst system is rare thus far.In this contribution,by introducing different backbones,flexible and rigid axial substituents into theα-imino-ketone framework,a family of cationic nickel catalysts were synthesized and fully characterized.Without the addition of any activator,systematic studies on ethylene polymerization and copolymerization with polar monomers were performed to explore the influence of both backbone and axial substituent on catalytic activity,polymer molecular weight,branching density and incorporation.In particular,owing to the unique semi-opening feature of theα-imino-ketone framework,the preferred nickel catalyst exhibited high activity of 175 kg·mol^(-1)·h^(-1)to produce functionalized polyethylene with molecular weight of 13.4 kg·mol^(-1)and comonomer incorporation of 2.9 mol%.

关键词： Olefin polymerization α-Imino-ketone ligand Nickel catalyst polar monomer

Direct Synthesis of Ultrahigh Molecular Weight Functionalized Isotactic Polypropylene

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CCS Chemistry 2023年第11期5卷 2638-2649页

作者： Guanglin Zhou Hongliang Mu Xin Ma Xiaohui Kang Zhongbao Jian State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022 University of Science and Technology of China Hefei 230026 College of Pharmacy Dalian Medical UniversityDalian 116044

Ultrahigh molecular weight functionalized isotactic polypropylene(f-UHMW-iPP)through the direct copolymerization of propylene with polar monomers is highly desirable but has not been accessed thus far because it involves challenging regio-and stereochemistry along with usually reduced molecular weight.Herein,in contrast to the unsuccessful catalyst strategy,a polar monomer-assisted strategy is used to access the above material.The introduction of O-or S-functionalized long-chain polar olefins into the hafnium-catalyzed copolymerization of propylene(and bulkierα-olefins)significantly increases the copolymer molecular weight with a maximum observed increase of+488%.f-UHMW-iPP and functionalized isotactic poly(α-olefin)s(M_(w)>2000 kDa,[mmmm]:99%)are thus prepared at ambient conditions.The incorporation of 1 mol%of polar monomer improves the surface property and significantly increases the long-sought toughness(860%)of brittle iPP,without reducing the tensile strength(42 MPa)due to the key achievement of ultrahigh molecular weight.A discussion of the mechanism involved in the beneficial effects of incorporating the polar monomer is herein presented by an in-depth density functional theory calculation.

关键词： homogeneous catalysis olefin polymerization polar monomer ultrahigh molecular weight functionalized isotactic polypropylene

Dual roles of trifluoroborate in nickel-catalyzed ethylene polymerization:Electronic perturbation and anchoring for heterogenization

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中国化学快报:英文版 2023年第8期34卷 352-355页

作者： Changwen Hong Zihao Wang Hui Jiang Guifu Si Maoping Song Changle Chen CAS Key Laboratory of Soft Matter Chemistry Department of Polymer Science and EngineeringUniversity of Science and Technology of ChinaHefei 230026China College of Chemistry Zhengzhou UniversityZhengzhou 450001China

Brookhart-typeα-diimine nickel and palladium catalysts have been extensively studied over the past several decades;however,the heterogenization of these metal complexes has received much less attention.In this contribution,we installed a trifluoroborate potassium substituent on anα-diimine framework.The ionic nature of trifluoroborate potassium endowed theα-diimine nickel complex with a strong affinity for the SiO_(2)support,while its electron-donating nature enhanced the catalyst stability and polyethylene molecular weight.In the presence of only 100 equiv.of Et2AlCl cocatalyst,the SiO_(2)-supported catalyst demonstrated significantly better performance than its homogeneous analog during ethylene polymerization,with extremely high activity(1.42–6.53×10^(7)g mol^(−1)h^(−1))and high thermal stability.The heterogeneous system led to the formation of high-molecular-weight polyethylenes(Mn 142,500–732,800 g/mol),narrow polydispersities(2.18–3.00),tunable branching densities(21–64 per 1000 carbon atoms),and great mechanical properties.Moreover,the efficient copolymerization of ethylene with comonomers such as methyl 10-undecenoate,6-chloro-1-hexene or 5-hexenylacetate was achieved.These superior properties enabled by the trifluoroborate potassium moiety may inspire its applications in other polymerization catalyst systems.

关键词： Nickel catalysts Heterogeneous catalysts Olefin polymerization polar monomer Copolymerization

ETHYLENE POLYMERIZATION AND COPOLYMERIZATION WITH polar monomerS BY A NEUTRAL NICKEL CATALYST COMBINED WITH CO-CATALYST OF Ni(COD)_2 OR AL(i-Bu)_3

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Chinese Journal of Polymer Science 2005年第3期23卷 301-310页

作者： Yu-huaShan 孙俊全 Yong-jinXu Yong-gangCui FengLin DepartmentofChemicalEngineering CollegeofMaterial＆ChemicalEngineeringZhejiangUniversityHangzhou310027China

A neutral nickel(Ⅱ)catalyst D,{[O-(3-cyclohexyl)(5-Cl)C_6H_2-ortho-C(H)=N-2,6-C_6H_3(i-Pr)_2]Ni(Ph_3P)(Ph)}hasbeen synthesized and characterized by IH-NMR,FTIR and elemental analysis.The results indicate that Al(i-Bu)_3 is aneffective cocatalyst for the neutral nickel catalyst.With bis(1,5-cyclooctadiene)nickel(0)[Ni(COD)_2]or Al(i-Bu)_3 as a co-catalyst,the neutral nickel catalyst D is active for ethylene polymerisation and copolymerisation with polar monomers(tert-butyl 10-undecenoate(BU),methyl 10-undecenoate(MU),allyl alcohol(AA)and 4-penten-1-ol(PO))under mild conditions.The resulting polymers were characterized by (?)H-NMR,FTIR,DSC,and GPC.From the comparative studies,Ni(COD)_2 ismore active than Al(i-Bu)_3 for ethylene homopolymerization,while Al(i-Bu)_3 is more effective than Ni(COD)_2 for ethylenecopolymerisation with polar monomers.The polymerization parameters which affect both the catalytic activity and propertiesof the resulting polyethylene were investigated in detail.Under the conditions of 20 μmol catalyst D and Ni(COD)_2/D=3(molar ratio) in 30 mL toluene solution at 45℃,12×105 Pa ethylene for 20 min,the polymerization activity reaches ashigh as 7.29×105 gPE.(mol.Ni.h)^(-1) and M_η,is 7.16×104 g.mol^(-1).For ethylene copolymerization with polar monomers,theeffect of comonomer concentrations was examined.As high as 0.97 mol% of MU,1.06 mol% of BU,1.04 mol% of AA and1.37 mol% of PO were incorporated into the polymer,respectively,catalyzed by D/Al(i-Bu)_3 system.

关键词： Neutral nickel catalyst polar monomer Copolymerization Polyethylene Functional polyolefins.

Benzosuberyl Substituents as a"Sandwich-like"Function in Olefin Polymerization Catalysis

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Chinese Journal of Polymer Science 2021年第8期39卷 984-993,I0006页

作者： Yu-Yin Wang Chao-Qun Wang Xiao-Qiang Hu Yan Xia Yue Chi Yi-Xin Zhang Zhong-Bao Jian College of Chemistry and Life Science Advanced Institute of Materials ScienceChangchun University ofTechnologyChangchun 130012China Key Laboratory of Advanced Structural Materials of Ministry of Education College of Material Science and EngineeringChangchun University of TechnologyChangchun 130012China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China

For the rational design of metal catalyst in olefin polymerization catalysis,various strategies were applied to suppress the chain transfer by bulking up the axial positions of the metal center,among which the"sandwich"type turned out to be an eficient category in achieving high molecular weight polyolefin.In the a-dimine system,the"sandwich"type catalysts were built using the typical 8-aryl-naphthyI framework.In this contribution,by introducing the rotationally restrained benzosuberyl substituent into the ortho-position of N-aryl rings,a new class of "sandwich-like"a-diimine nickel catalysts was constructed and fully identified.The rotationally restrained benzosuberyl substituents played a"sandwich-like"function by capping the nickel center from two axial sites.Compared to the nickel catalyst Ni1 bearing freely rotated benzhydryl substituent,Ni2 featuring benzosubery|substituent enabled the increase(8 times)of polymer molecular weights from 8 kDa to 65 kDa in the polymerization of ethylene.By further increasing the steric bulk of another ortho-site of the N-aryl ring,the polymer molecular weight even reached an ultrahigh level of 833 kDa(Mw=1857 kDa)using the optimized Ni3.Notably,these nickel catalysts could also mediate the copolymerization of ethylene with methyl 10-undecenoate,with Ni3 giving the highest copolymer molecular weight(88 kDa)and the highest incorporation of comonmer(2.0 mol1%),along with high activity of up to 10^(5)g·mol^(-1)·h^(-1).

关键词： Olefin polymerization Benzosuberyl substituent Sandwich Nickel catalyst polar monomer

Research on poly(styrene-acrylic acid)-supported neodymium complex in catalytic copolymerization of styrene and 4-vinylpyridine

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Journal of Rare Earths 2008年第3期26卷 326-330页

作者：陈瑞战李晓莉王晓菊张永宏赵伦 College of Chemistry Changchun Normal University

The catalytic activity of poly（styrene-acrylic acid）（PSAA） supported neodymium chloride （NdCl3） complex for the copolymerization of styrene and 4-Vinylpyridine was studied. The influence of various factors, such as Al/Nd molar ratio, reaction time, macromolecular carder （PSAA）, and ratio of styrene to 4-vinypyridine （g/g）, on the copolymerization yield of styrene and 4-Vinylpyridine was investigated. The results showed that the copolymerization of polar monomers with olefins occurred efficiently and the catalytic activity of polymer-supported catalyst was higher than that of the similar small molecular catalysts. The activity of PSAA.Nd complex increased with in- creasing Al/Nd molar ratios and decreased with increasing polymerization time. The highest activity of PSAA＇Nd was observed at 120 min, and the highest yield was found at the ratio of styrene to 4-vinylpyridine of 4：2. DSC analysis presented that the resulted polymer had only one glass transition temperature, and showed very good thermal stability.

关键词： rare earth catalyst styrene 4-vinylpyridine polar monomer copolymerization rare earths