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原子转移自由基聚合制备两亲性聚乳酸嵌段共聚物 总被引:2,自引:0,他引:2
以双端羟基聚乳酸和2-溴丙酰溴为原料,制备了溴端基的聚乳酸;再以此作为大分子引发剂,溴化亚铜/2,2’-联吡啶为催化体系,实现了N-乙烯基吡咯烷酮的原子转移自由基聚合,制得了两亲性聚乳酸嵌段共聚物。用IR、^1H-NMR、GPC和接触角测定仪对聚合物的结构和亲水性进行了表征,并用TEM研究了聚合物在水溶液中的聚集状态。结果表明,聚乙烯基吡咯烷酮链段的引人,大大提高了聚乳酸共聚物的亲水性,且共聚物在水相中可形成一壳多核球状胶束。 相似文献
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本文综述了采用原子转移自由基聚合(ATRP)法合成接枝共聚物的研究进展。主要从大分子引发剂法和大分子单体法两方面介绍了原子转移自由基聚合在合成接枝聚合物中的应用。 相似文献
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采用原子转移自由基聚合(ATRP)法,以三羟甲基丙烷为核制备引发剂,以苯乙烯为单体,合成三臂聚苯乙烯星形聚合物,并用傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H-NMR)、凝胶渗透色谱(GPC)对所得引发剂和聚合物的结构进行了表征。结果表明,FTIR证实了三臂引发剂和聚苯乙烯的存在。1H-NMR分析证实,采用ATRP法可以成功合成出目标产物星形聚苯乙烯。GPC分析证明了所得产物的数均分子量为2 700~9 460,基本符合预期值;多分散性指数仅为1.01~1.05,具备活性聚合特征。 相似文献
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利用原子转移自由基聚合,以α,α′-二氯对二甲苯为双功能引发剂,在CuCl/2,2′-联吡啶配位化合物催化下,采用二段聚合法合成了苯乙烯/丙烯酸丁酯/苯乙烯三嵌段共聚物,用GPC测定了嵌段共聚物的相对分子质量及其分布。 相似文献
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以不同不稳定氯含量的聚氯乙烯(PVC)为大分子引发剂,CuCl2/三(2-吡啶甲基)胺(TPMA)为催化体系,抗坏血酸(AA)为还原剂,通过水相电子转移催化再生原子转移自由基聚合(ARGETATRP)制备PVC接枝丙烯酸丁酯(BA)共聚物(PVC-g-BA),研究聚合条件对BA聚合转化率和接枝率的影响。发现其它聚合条件相同时,采用不稳定氯含量高的PVC为大分子引发剂制备的PVC-g-BA的接枝PBA的平均分子量较低;随着BA单体用量增加,聚合转化率和接枝率增大;随着催化剂CuCl2用量和聚合温度的增加,转化率和接枝率先增加后减小;当PVC为1.589 g,BA为2.70 g,CuCl2用量为0.0048 g,AA/TPMA/CuCl2(mol)=15/5/1,聚合温度为70℃,可获得BA转化率为56.06%、接枝率为95.14%的PVC-g-BA产物;由于PVC仅部分溶胀于BA,导致PVC接枝不均匀,PVC-g-BA分子量分布出现双峰现象,接枝PBA的分子量大于理论分子量。 相似文献
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A new asymmetric H-shaped block copolymer (PS)2-PEO-(PMMA)2 has been designed and successfully synthesized by the combination of atom transfer radical polymerization and living anionic polymerization. The synthesized 2,2-dichloro acetate-ethylene glycol (DCAG) was used to initiate the polymerization of styrene by ATRP to yield a symmetric homopolymer (Cl-PS)2-CHCOOCH2CH2OH with an active hydroxyl group. The chlorine was removed to yield the (PS)2-CHCOOCH2CH2OH ((PS)2-OH). The hydroxyl group of the (PS)2-OH, which is an active species of the living anionic polymerization, was used to initiate ethylene oxide by living anionic polymerization via DPMK to yield (PS)2-PEO-OH. The (PS)2-PEO-OH was reacted with the 2,2-dichloro acetyl chloride to yield (PS)2-PEO-OCCHCl2 ((PS)2-PEO-DCA). The asymmetric H-shaped block polymer (PS)2-PEO-(PMMA)2 was prepared via ATRP of MMA at 130 °C using (PS)2-PEO-DCA as initiator and CuCl/bPy as the catalyst system. The architectures of the asymmetric H-shaped block copolymers, (PS)2-PEO-(PMMA)2, were confirmed by 1H NMR, GPC and FT-IR. 相似文献
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Amphiphilic diblock copolymers of polystyrene-b-poly(methacrylic acid) were synthesized by means of atom transfer radical polymerization. First, the polystyrene with a bromine atom at the chain end (PS-Br) was prepared using styrene as the monomer, 1-bromoethyl benzene as the initiator, and CuCl/2,2′-bipyridyl (bpy) as the catalyst ([1-bromoethyl benzene]/[CuCl]/[bpy] = 1:1:3). The polymerization was well controlled. Second, the diblock copolymer of polystyrene-b-poly(tert-butyl methacrylate) was synthesized also by atom transfer radical polymerization using PS-Br as the macro-initiator, CuCl/bpy as the catalyst, and tert-butyl methacrylate (tBMA) as the monomer. Finally, the amphiphilic diblock copolymer, PS-b-PMAA, was obtained by hydrolysis of PS-b-PtBMA under the acid condition. The molecular weight and the structure of aforementioned copolymers were characterized with gel permeation chromatography, infrared, and nuclear magnetic resonance. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2381–2386, 2001 相似文献
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Submicron-sized poly(i-butyl methacrylate)-block-polystyrene particles were successfully prepared by two-step atom transfer radical polymerization (ATRP) in aqueous media: ATRP in miniemulsion (miniemulsion-ATRP) followed by ATRP in seeded emulsion polymerization (seeded-ATRP). When PiBMA particles, which were prepared by the miniemulsion-ATRP process with polyoxyethylene sorbitan monooleate (Tween 80, nonionic emulsifier) of 6-10 wt % based on iBMA, were used as seed in the seeded-ATRP of styrene, the block copolymer particles having narrow molecular weight distribution and pre-determined molecular weight were prepared at high conversion. Some block copolymer particles had an ‘onion-like’ multilayered structure. In this way, controlled/living free radical polymerization can be employed to obtain unique particle morphologies that may not be easily accessible using conventional free radical polymerization. 相似文献
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A combination of coordination polymerization and atom transfer radical polymerization (ATRP) was applied to a novel synthesis of rod–brush block copolymers. The procedure included the following steps: (1) the monoesterification reaction of ethylene glycol with 2-bromoisobutyryl bromide (BIBB) yielded the bifunctional initiator monobromobutyryloxy ethylene glycol and (2) a trichlorocyclopentadienyl titanium (CpTiCl3; bifunctional initiator) catalyst was prepared from a mixture of CpTiCl3 and bifunctional initiator. The coordination polymerization of n-butyl isocyanate initiated by such a catalyst provided a well-defined macroinitiator, poly(n-butyl isocyanate)–bromine (PBIC–Br). (3) The ATRP method of 2-hydroxyethyl methacrylate initiated by PBIC–Br provided rod [poly(n-butyl isocyanate) (PBIC)]–coil [poly(2-hydroxyethyl methacrylate) (PHEMA)] block copolymers with a CuCl/CuCl2/2,2′-bipyridyl catalyst. (4) The esterfication of PBIC-block-PHEMA with BIBB yielded a block-type macroinitiator, and (5) ATRP of methyl methacrylate with a block-type macroinitiator provided rod–brush block copolymers. We found from the solution properties that such rod–brush block copolymers formed nanostructured macromolecules in solution. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
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FeCl3 coordinated by succinic acid was used as the catalyst for the first time in azobisisobutyronitrile‐initiated reverse atom transfer radical polymerization of acrylonitrile (AN). N,N‐dimethylformamide (DMF) was used as a solvent to improve the solubility of the ligand. A FeCl3 to succinic acid ratio of 0.5 not only gives the best control of molecular weight and its distribution but also provides rather rapid reaction rate. Effects of different solvents on polymerization of AN were also investigated. The rate of the polymerization in DMF is faster than that in propylene carbonate and toluene. The molecular weight of polyacrylonitrile agrees reasonably well with the theoretical molecular weight in DMF. The rate of polymerization increases with increasing the polymerization temperature, and the apparent activation energy was calculated to be 64.8 kJ mol?1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 32–36, 2006 相似文献
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Amphiphilic diblock and crosslinked copolymers synthesized via metal‐free atom transfer radical polymerization 下载免费PDF全文
The use of metal‐free atom transfer radical polymerization (MF‐ATRP) was explored for the formation of diverse macromolecular structures to assess the versatility of this advanced polymerization process. In MF‐ATRP using an organic photocatalyst, 10‐phenylphenothiazine, the influences of various monomers, initiators and solvents were examined, showing that molecular weight and polydispersity could be tailored through appropriate selection of each component. Using this modern polymerization technology, metal‐free amphiphilic diblock and crosslinked copolymers were prepared successfully. Especially, demonstration of amphiphilic diblock copolymer synthesis provides a basis for further applications to biomedical materials. © 2017 Society of Chemical Industry 相似文献
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Bis[(4 ‐β‐(2‐bromopropanoate)ethoxy)phenyl]phenylphosphine oxide was used for the first time as the initiator of atom transfer radical polymerization of styrene and methyl methacrylate in the presence of CuBr/N, N,N′, N″, N″‐pentamethyldiethylenetriamine as catalyst/ligand and dimethyl sulfoxide as solvent. The presence of phosphine oxide linkages in the backbone gives the polymers special properties; low Tg, high char yield, and decreases the oxygen induction time value. A linear increase of number average molecular weight (Mn) versus monomer conversion was observed, and the molecular weight distribution was relatively narrow (Mw/Mn = 1.1–1.3). FTIR, 1HNMR, gel permeation chromatography, ultraviolet spectroscopies were used for the characterization of the related polymers. The thermal properties of these polymers were investigated by differential scanning calorimetry and thermogravimetric analysis. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
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Gabriel J Summers B
M Parveen Beebeejaun Carol A Summers 《Polymer International》2000,49(12):1722-1728
The synthesis of aromatic carboxyl functionalized polymers by atom transfer radical polymerization is described. The α‐bromo‐p‐toluic acid ( 1 ) initiated polymerization of styrene in the presence of copper(I) bromide and 2,2′‐bipyridyl affords quantitative yields of the corresponding aromatic carboxyl functionalized polystyrene ( 2 ). Polymerization proceeded via a controlled free radical process to afford quantitative yields of the corresponding aromatic carboxyl functionalized polymers with predictable molecular weights (Mn = 1600–25 900 g mol−1), narrow molecular weight distribution (Mw /Mn = 1.1–1.40) and an initiator efficiency above 0.87. The polymerization process was monitored by gas chromatographic analysis. The functionalized polymers were characterized by thin layer chromatography, size exclusion chromatography, spectroscopy, potentiometry and elemental analysis. © 2000 Society of Chemical Industry 相似文献
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A novel free radical interfacial copolymerization was proposed and used to prepare the amphiphilic block copolymer of acrylamide (AM) with styrene (S). In this copolymerization, a synthesized new kind of initiator, namely, amphiphilic bifunctional initiator, which has not only a hydrophilic and a hydrophobic group but also two functional groups generating radicals in both ends of its molecule, was used to initiate the interfacial copolymerization. The generated amphiphilic block copolymer was characterized by infrared analysis, differential scanning calorimetry, elemental analysis, and dissolution behavior. The migration of generated copolymer from interface to water phase was discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 443–449, 1998 相似文献