Diimine)nickel {[C 6 H 5 -N = C(CH 3 ) - C(CH 3 ) = N - QH 5 ]NiBr 2 }-TiCl 4 , abbreviated as NiL-TiCl 4 combined catalyst which is supported on MgCl 2 -SiO 2 carrier has been prepared, by using alkyl aluminum (AlR 3...Diimine)nickel {[C 6 H 5 -N = C(CH 3 ) - C(CH 3 ) = N - QH 5 ]NiBr 2 }-TiCl 4 , abbreviated as NiL-TiCl 4 combined catalyst which is supported on MgCl 2 -SiO 2 carrier has been prepared, by using alkyl aluminum (AlR 3 ) as the cocatalyst in place of methylaluminoxane (MAO) to catalyze ethylene oligomerization and copolymerization in situ. The influences of procedure for supporting NiL-TiCl 4 , the molar ratio of NiL to TiCl 4 , cocatalyst type and polymerization temperature on the catalytic performance were studied. The degree of branching and the composition of the branched chain of polymers produced have been investigated by IR and 13C-NMR spectra. The results show that the combined catalyst can synthesize the branched polyethylene with various banched chains .The polymerization reaction was monitored by gas chromatography and mass spectrometry (GC-MS). The results show that this catalyst promotes the oligomerization and copolymerization in situ for ethylene.展开更多
Branched polyethylene from ethylene as single monomer was prepared by the tandem catalyst system of {2-[2-Me C6H4 N（Me）]2C5H3N}FeCl2（1） and {2,6-[1-(2,6-Me2-4-Br-C6H4N（Me）]2C5H3N} FeCl2（2） activated with methy...Branched polyethylene from ethylene as single monomer was prepared by the tandem catalyst system of {2-[2-Me C6H4 N（Me）]2C5H3N}FeCl2（1） and {2,6-[1-(2,6-Me2-4-Br-C6H4N（Me）]2C5H3N} FeCl2（2） activated with methylaluminoxane （MAO） .The products of polymerization were characterized by DSC,GPC and （）13C-NMR.The results revealed that the copolymer produced by in situ copolymerization of ethylene was a mixture of branched polyethylene and α-olefin.The content of α-olefin in the mixture was increased with increasing the molar ratio of catalysts 1/2.The MWD paramelers of polyethylene and copolymer were 28\^6 and 7\^9, respectively.（）13C-NMR spectra showed that there were ethyl groups,butyl groups and long chain alkyl groups in the copolymer.The average degree of branching of such branched polyethylene was less than 5C/1000C.展开更多
Hyperbranched polyacrylate copolymers were synthesized by self\|condensing vinyl copolymerization (SCVCP) of 2\|[(2\|bromopropionyl)oxy]ethyl acrylate(BPEA) and methyl acrylate(MA) in the presence of a tetrafunctional...Hyperbranched polyacrylate copolymers were synthesized by self\|condensing vinyl copolymerization (SCVCP) of 2\|[(2\|bromopropionyl)oxy]ethyl acrylate(BPEA) and methyl acrylate(MA) in the presence of a tetrafunctional initiator(THABI).The structures of the polymers obtained were characterized by 1H\|NMR and SEC/refractive index(RI)/right anagle laser light scattering(RALLS)/differential viscometer(DV).Molecular weight(MW),molecular weight distribution(MWD) and degree of branching(DB) were influenced by conversion and initial feed molar ratio of BPEA,MA and THABI.The addition of THABI can narrow the MWDs of the polymers obtained.The results are consistent with our simulation result.展开更多
A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis,with ethylene as single monomer.Such catalytic ...A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis,with ethylene as single monomer.Such catalytic system is composed of β-diketonate zirconium complexes,i.e.(acac)2ZrCl2(Ⅰ)and(dbm)2ZrCl2(Ⅱ)as catalyst precursors,diethylaluminium chloride(AlEt2Cl)as a co-catalyst for ethylene oligomerization and methylaluminoxane(MAO)as another one for the in situ copolymerization with ethylene.The oligomers obtained were mainly α-olefins,and the contents of them in weight were 76.84 for Ⅰ and 65.99 for Ⅱ,while the part being able to be copolymerized was 62.12 and 55.32 for Ⅰ and Ⅱ,respectively.The branched polyethylene via in situ copolymerization of ethylene was prepared by the tandem catalytic system Ⅰ/AlEt2Cl/MAO or Ⅱ/AlEt2Cl/MAO.13C NMR spectrum reveals that the resultant copolymer was branched polyethylene with total branches of 2.1/1000C,including ethyl group of 1.2/1000C,butyl group of 0.8/1000C and longer branches of 0.1/1000C.With increasing the molar ratio of AlEt2Cl to MAO,the melting temperature of the polymer obtained decreased from 133.7 to 116.7 ℃ for Ⅰ/AlEt2Cl/MAO and from 131.7 to 118.8 ℃ for Ⅱ/AlEt2Cl/MAO as well as the change of crystallinity.The catalytic activities for catalyst Ⅰ/AlEt2Cl/MAO and Ⅱ/AlEt2Cl/MAO were from 2.48×104 to 0.10×104 g PE/(mol Zr·h)and from 1.00×104 to 0.32×104 g PE/(mol Zr·h),respectively.The results indicate that the branched polyethylene can be obtained by such a catalytic system.展开更多
Here,we demonstrate the use of branched macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agents in RAFT dispersion polymerization,to access branched block copolymers as well as well-defined...Here,we demonstrate the use of branched macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agents in RAFT dispersion polymerization,to access branched block copolymers as well as well-defined branched block copolymer assemblies.Two types of branched macro-RAFT agents were first synthesized by using either a monofunctional chain transfer monomer or a difunctional chain transfer monomer in RAFT polymerization,and subsequently utilized in RAFT dispersion polymerization.It was found that only branched macro-RAFT agents synthesized from the difunctional chain transfer monomer could lead to colloidally stable assemblies with well-defined morphologies.Reaction conditions including monomer concentration,degree of polymerization (DP) of the core-forming block,and DP of the solvophilic segment on morphologies of branched block copolymer assemblies were investigated in detail.Size exclusion chromatography (SEC) analysis further confirmed the successful formation of branched block copolymers by using branched macro-RAFT agents.This work on the synthesis of branched block copolymer assemblies by RAFT dispersion polymerization offers new opportunities for the rational design of polymer assemblies with well-defined structures.展开更多
基金This project was supported by the National Natural Science Foundation of China (No. 29874039) and the Foundation ofGuangdong Province (No. 031598).
文摘Diimine)nickel {[C 6 H 5 -N = C(CH 3 ) - C(CH 3 ) = N - QH 5 ]NiBr 2 }-TiCl 4 , abbreviated as NiL-TiCl 4 combined catalyst which is supported on MgCl 2 -SiO 2 carrier has been prepared, by using alkyl aluminum (AlR 3 ) as the cocatalyst in place of methylaluminoxane (MAO) to catalyze ethylene oligomerization and copolymerization in situ. The influences of procedure for supporting NiL-TiCl 4 , the molar ratio of NiL to TiCl 4 , cocatalyst type and polymerization temperature on the catalytic performance were studied. The degree of branching and the composition of the branched chain of polymers produced have been investigated by IR and 13C-NMR spectra. The results show that the combined catalyst can synthesize the branched polyethylene with various banched chains .The polymerization reaction was monitored by gas chromatography and mass spectrometry (GC-MS). The results show that this catalyst promotes the oligomerization and copolymerization in situ for ethylene.
文摘Branched polyethylene from ethylene as single monomer was prepared by the tandem catalyst system of {2-[2-Me C6H4 N（Me）]2C5H3N}FeCl2（1） and {2,6-[1-(2,6-Me2-4-Br-C6H4N（Me）]2C5H3N} FeCl2（2） activated with methylaluminoxane （MAO） .The products of polymerization were characterized by DSC,GPC and （）13C-NMR.The results revealed that the copolymer produced by in situ copolymerization of ethylene was a mixture of branched polyethylene and α-olefin.The content of α-olefin in the mixture was increased with increasing the molar ratio of catalysts 1/2.The MWD paramelers of polyethylene and copolymer were 28\^6 and 7\^9, respectively.（）13C-NMR spectra showed that there were ethyl groups,butyl groups and long chain alkyl groups in the copolymer.The average degree of branching of such branched polyethylene was less than 5C/1000C.
文摘Hyperbranched polyacrylate copolymers were synthesized by self\|condensing vinyl copolymerization (SCVCP) of 2\|[(2\|bromopropionyl)oxy]ethyl acrylate(BPEA) and methyl acrylate(MA) in the presence of a tetrafunctional initiator(THABI).The structures of the polymers obtained were characterized by 1H\|NMR and SEC/refractive index(RI)/right anagle laser light scattering(RALLS)/differential viscometer(DV).Molecular weight(MW),molecular weight distribution(MWD) and degree of branching(DB) were influenced by conversion and initial feed molar ratio of BPEA,MA and THABI.The addition of THABI can narrow the MWDs of the polymers obtained.The results are consistent with our simulation result.
文摘A novel catalytic system to prepare branched polyethylene with single catalyst activated by two different co-catalysts is reported in this paper via the tandem catalysis,with ethylene as single monomer.Such catalytic system is composed of β-diketonate zirconium complexes,i.e.(acac)2ZrCl2(Ⅰ)and(dbm)2ZrCl2(Ⅱ)as catalyst precursors,diethylaluminium chloride(AlEt2Cl)as a co-catalyst for ethylene oligomerization and methylaluminoxane(MAO)as another one for the in situ copolymerization with ethylene.The oligomers obtained were mainly α-olefins,and the contents of them in weight were 76.84 for Ⅰ and 65.99 for Ⅱ,while the part being able to be copolymerized was 62.12 and 55.32 for Ⅰ and Ⅱ,respectively.The branched polyethylene via in situ copolymerization of ethylene was prepared by the tandem catalytic system Ⅰ/AlEt2Cl/MAO or Ⅱ/AlEt2Cl/MAO.13C NMR spectrum reveals that the resultant copolymer was branched polyethylene with total branches of 2.1/1000C,including ethyl group of 1.2/1000C,butyl group of 0.8/1000C and longer branches of 0.1/1000C.With increasing the molar ratio of AlEt2Cl to MAO,the melting temperature of the polymer obtained decreased from 133.7 to 116.7 ℃ for Ⅰ/AlEt2Cl/MAO and from 131.7 to 118.8 ℃ for Ⅱ/AlEt2Cl/MAO as well as the change of crystallinity.The catalytic activities for catalyst Ⅰ/AlEt2Cl/MAO and Ⅱ/AlEt2Cl/MAO were from 2.48×104 to 0.10×104 g PE/(mol Zr·h)and from 1.00×104 to 0.32×104 g PE/(mol Zr·h),respectively.The results indicate that the branched polyethylene can be obtained by such a catalytic system.
基金support from the National Natural Science Foundation of China(Grant 52222301,21971047,and 22171055)the Guangdong Natural Science Foundation for Distinguished Young Scholar(Grant 2022B1515020078)the Science and Technology Program of Guangzhou(Grant 202102020631).
文摘Here,we demonstrate the use of branched macromolecular reversible addition-fragmentation chain transfer (macro-RAFT) agents in RAFT dispersion polymerization,to access branched block copolymers as well as well-defined branched block copolymer assemblies.Two types of branched macro-RAFT agents were first synthesized by using either a monofunctional chain transfer monomer or a difunctional chain transfer monomer in RAFT polymerization,and subsequently utilized in RAFT dispersion polymerization.It was found that only branched macro-RAFT agents synthesized from the difunctional chain transfer monomer could lead to colloidally stable assemblies with well-defined morphologies.Reaction conditions including monomer concentration,degree of polymerization (DP) of the core-forming block,and DP of the solvophilic segment on morphologies of branched block copolymer assemblies were investigated in detail.Size exclusion chromatography (SEC) analysis further confirmed the successful formation of branched block copolymers by using branched macro-RAFT agents.This work on the synthesis of branched block copolymer assemblies by RAFT dispersion polymerization offers new opportunities for the rational design of polymer assemblies with well-defined structures.
