The polymerization of n-butyl methacrylate was investigated using the Atom Transfer Radical Polymerization technique with CuBr and CuCl/N,N,N',N',N'-pentamethyldiethylenetriamine catalytic systems. Various...The polymerization of n-butyl methacrylate was investigated using the Atom Transfer Radical Polymerization technique with CuBr and CuCl/N,N,N',N',N'-pentamethyldiethylenetriamine catalytic systems. Various combinations of catalyst systems and initiators were utilized in order to optimize the polymerization conditions and to obtain well-defined polymers (i.e. controlled molecular weights and low polydispersities). It has been found that the optimal initiator for this system is a chlorine-based initiator, when the catalyst used is a salt in conjunction with the N,N,N',N',N'- pentamethyldiethylenetriamine ligand. Bromine-based initiators tend to result in large amounts of initial termination, leading to polymers with less than ideal chain end functionality, even if CuCl is used as the species to invoke the halogen exchange. Additionally, the effects of the polymerization temperature, species and the initiator structure were determined.展开更多
Fe(Ⅱ)pyridinebisimine complexes activated with trialkylaluminium or modified methylaluminoxane(MMAO)ascatalysts were employed for the polymerization of butyl methacrylate(BMA).Polymer yields,catalytic activities andm...Fe(Ⅱ)pyridinebisimine complexes activated with trialkylaluminium or modified methylaluminoxane(MMAO)ascatalysts were employed for the polymerization of butyl methacrylate(BMA).Polymer yields,catalytic activities andmolecular weights as well as molecular weight distributions of BMA can be controlled over a wide range by varying thereaction parameters such as cocatalyst,Al/Fe molar ratio,monomer/catalyst molar ratio,monomer concentration and reactiontemperature used in the polymerization.The catalytic activity of Fe(Ⅱ)complex was 11.1 kg_(polym)/mol_(Fe)h and the highestyield could reach 99.1% under optimum condition.展开更多
A new kind of zirconium(Zr) complex containing ligand of salicylaldehyde-imine was successfully synthesized with ZrCl_4·2 THF and salicylaldehyde-imine as raw materials. The ligand was characterized by means of...A new kind of zirconium(Zr) complex containing ligand of salicylaldehyde-imine was successfully synthesized with ZrCl_4·2 THF and salicylaldehyde-imine as raw materials. The ligand was characterized by means of ~1HNMR, IR, and GC-MS, and Zr complex was characterized by means of ~1HNMR and IR, respectively. The Zr complex, combined with co-catalyst of Al(i-Bu)_3, was explored to be effective catalytic system for the polymerization of butyl methacrylate(BMA), to prepare poly-n-butyl methacrylate(PBMA), which was characterized by IR, ~13C-NMR and GPC. Compared with other double-component(MAO/Cat, AlEt_3/Cat) catalytic systems, catalytic system of Al(i-Bu)_3 and the Zr complex provided the best catalytic activity under the same conditions. The influence of polymerization parameters, such as molar ratio of Al(i-Bu)_3/Cat and BMA/Cat, polymerization temperature and polymerization time, was studied with Zr complex/Al(i-Bu)_3 system. With increasing polymerization time from 4 to 24 hour, the monomer conversion increased from 40.14% to 96.56%. Viscosity-average molecular weight(M_v) of PBMA, detected by the viscosity methodology, increased from 12.67×10~4Da to 44.97×10~4Da and lower molecular weight distribution was obtained. According to these results, the Zr complex contained ligand of salicylaldehyde-imine was a kind of readily, long lifetime and high activity catalyst for BMA polymerization.展开更多
P(BA-GMA)(PBG), having various molecular weights, was synthesized by in situ polymerization of butyl acrylate(BA) and glycidyl methacrylate(GMA), and further used as a modifier to improve the comprehensive pro...P(BA-GMA)(PBG), having various molecular weights, was synthesized by in situ polymerization of butyl acrylate(BA) and glycidyl methacrylate(GMA), and further used as a modifier to improve the comprehensive properties of the epoxy curing system. The copolymers were characterized by gel permeation chromatography(GPC). The effects of various molecular weights of copolymers on the mechanical properties, thermal performance, and phase behavior of the curing system were carefully evaluated. The experimental results of differential scanning calorimetry(DSC) and dynamic mechanical analysis(DMA) showed that glass transition temperature decreased and the tan δ peak shifted to a lower temperature with decreasing molecular weight of copolymer. Mechanical properties analysis of curing films showed that the impact strength and fracture toughness increased significantly upon the addition of PBG, indicating good toughness of the modified epoxy resins. From scanning electron microscopy(SEM) studies of the fracture surfaces of ER/PBG systems, the fracture behavior of epoxy matrix was changed from brittleness to toughness.展开更多
Miniemulsion stabilized by poly(2-(dimethylamino) ethyl methacrylate)-block-poly(butyl methylacrylate)(PDMAEMA-b-PBMA) diblock copolymers has been used as liquid templates for the synthesis of polymer nanocaps...Miniemulsion stabilized by poly(2-(dimethylamino) ethyl methacrylate)-block-poly(butyl methylacrylate)(PDMAEMA-b-PBMA) diblock copolymers has been used as liquid templates for the synthesis of polymer nanocapsules via quaternization cross-linking of PDMAEMA segments of the copolymer by 1,2-bis(2-iodoethoxy)ethane(BIEE) crosslinkers. PDMAEMA-b-PBMAs here as a stabilizer in miniemulsion with different molecular weights led to a size variation in diameters of nanocapsules, demonstrating the capsules have potential design capability of this technique. The solution behavior of the capsules has been also investigated in this paper.展开更多
基金Financial support from the National Science Foundation (DMR-0090499) and CRP Consortium at Carnegie MellonUniversity is gratefully acknowledged.
文摘The polymerization of n-butyl methacrylate was investigated using the Atom Transfer Radical Polymerization technique with CuBr and CuCl/N,N,N',N',N'-pentamethyldiethylenetriamine catalytic systems. Various combinations of catalyst systems and initiators were utilized in order to optimize the polymerization conditions and to obtain well-defined polymers (i.e. controlled molecular weights and low polydispersities). It has been found that the optimal initiator for this system is a chlorine-based initiator, when the catalyst used is a salt in conjunction with the N,N,N',N',N'- pentamethyldiethylenetriamine ligand. Bromine-based initiators tend to result in large amounts of initial termination, leading to polymers with less than ideal chain end functionality, even if CuCl is used as the species to invoke the halogen exchange. Additionally, the effects of the polymerization temperature, species and the initiator structure were determined.
基金This work was supported by the National Natural Science Foundation of China(No.20174040)SINOPEC(No.20334030)+1 种基金by the Special Funds for Major State Basis Research Projects(No.G1999064801)of the Ministry of ScienceTechnology of China.
文摘Fe(Ⅱ)pyridinebisimine complexes activated with trialkylaluminium or modified methylaluminoxane(MMAO)ascatalysts were employed for the polymerization of butyl methacrylate(BMA).Polymer yields,catalytic activities andmolecular weights as well as molecular weight distributions of BMA can be controlled over a wide range by varying thereaction parameters such as cocatalyst,Al/Fe molar ratio,monomer/catalyst molar ratio,monomer concentration and reactiontemperature used in the polymerization.The catalytic activity of Fe(Ⅱ)complex was 11.1 kg_(polym)/mol_(Fe)h and the highestyield could reach 99.1% under optimum condition.
基金Funded by the Natural Science Foundation of Hubei Province(2017CFB680)the Excellent Youth Project of Hubei Provincial Department of Education(Q20162806)+1 种基金the National Undergraduate Science Foundation of China(No.201510488004)the Open Foundation of Hubei Province Key Laboratory of Coal Conversion and Novel Materials(WKDM201509)
文摘A new kind of zirconium(Zr) complex containing ligand of salicylaldehyde-imine was successfully synthesized with ZrCl_4·2 THF and salicylaldehyde-imine as raw materials. The ligand was characterized by means of ~1HNMR, IR, and GC-MS, and Zr complex was characterized by means of ~1HNMR and IR, respectively. The Zr complex, combined with co-catalyst of Al(i-Bu)_3, was explored to be effective catalytic system for the polymerization of butyl methacrylate(BMA), to prepare poly-n-butyl methacrylate(PBMA), which was characterized by IR, ~13C-NMR and GPC. Compared with other double-component(MAO/Cat, AlEt_3/Cat) catalytic systems, catalytic system of Al(i-Bu)_3 and the Zr complex provided the best catalytic activity under the same conditions. The influence of polymerization parameters, such as molar ratio of Al(i-Bu)_3/Cat and BMA/Cat, polymerization temperature and polymerization time, was studied with Zr complex/Al(i-Bu)_3 system. With increasing polymerization time from 4 to 24 hour, the monomer conversion increased from 40.14% to 96.56%. Viscosity-average molecular weight(M_v) of PBMA, detected by the viscosity methodology, increased from 12.67×10~4Da to 44.97×10~4Da and lower molecular weight distribution was obtained. According to these results, the Zr complex contained ligand of salicylaldehyde-imine was a kind of readily, long lifetime and high activity catalyst for BMA polymerization.
基金Funded by the National Natural Science Foundation of China(51373129)the Fundamental Research Funds for the Central University(WUT:2013-IV-011)
文摘P(BA-GMA)(PBG), having various molecular weights, was synthesized by in situ polymerization of butyl acrylate(BA) and glycidyl methacrylate(GMA), and further used as a modifier to improve the comprehensive properties of the epoxy curing system. The copolymers were characterized by gel permeation chromatography(GPC). The effects of various molecular weights of copolymers on the mechanical properties, thermal performance, and phase behavior of the curing system were carefully evaluated. The experimental results of differential scanning calorimetry(DSC) and dynamic mechanical analysis(DMA) showed that glass transition temperature decreased and the tan δ peak shifted to a lower temperature with decreasing molecular weight of copolymer. Mechanical properties analysis of curing films showed that the impact strength and fracture toughness increased significantly upon the addition of PBG, indicating good toughness of the modified epoxy resins. From scanning electron microscopy(SEM) studies of the fracture surfaces of ER/PBG systems, the fracture behavior of epoxy matrix was changed from brittleness to toughness.
基金supported by the National Natural Science Foundation of China(No.41402037)the Natural Science Foundation of Anhui Province Education Department(Nos.AQKJ2015B002 and KJ2014A141)
文摘Miniemulsion stabilized by poly(2-(dimethylamino) ethyl methacrylate)-block-poly(butyl methylacrylate)(PDMAEMA-b-PBMA) diblock copolymers has been used as liquid templates for the synthesis of polymer nanocapsules via quaternization cross-linking of PDMAEMA segments of the copolymer by 1,2-bis(2-iodoethoxy)ethane(BIEE) crosslinkers. PDMAEMA-b-PBMAs here as a stabilizer in miniemulsion with different molecular weights led to a size variation in diameters of nanocapsules, demonstrating the capsules have potential design capability of this technique. The solution behavior of the capsules has been also investigated in this paper.