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Low molecular weight triblock copolymers (TBCs) with poly(styrene-co-acrylonitrile) (SAN) end-blocks and poly(ethylene oxide) (PEO), poly(propylene oxide) (PPO) or polycaprolactone (PCL) mid-blocks were synthesized using atom transfer radical polymerization (ATRP). The influence of molecular weight, composition (mid-block mole fraction), and interaction parameter on the crystallinity and on the formation of an ordered nanoscale phase-separated structure was investigated using thermal analysis, X-ray scattering, and electron microscopy. The TBCs with PEO mole fractions of over 0.5 exhibited PEO crystallinities of around 40% (compared to 72% for the PEO homopolymer) and lamellar nanoscale periodicities of around 176 Å (compared to 143 Å for the PEO homopolymer). The TBCs with PEO, PCL or PPO mole fractions of less than 0.5 exhibited relatively low crystallinities and did not exhibit ordered structures. These results emphasize the importance of the mid-block mole fraction in determining the ability to form an ordered nanoscale structure through mid-block crystallization. The ordered structure disappeared on heating the TBCs above the mid-block melting point, but below the SAN glass transition temperature. The crystallinity was reduced significantly in TBCs that were annealed or cast from a solvent. 相似文献
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概述了原子转移自由基聚合(ATRP)在引发体系、反应温度、反应介质、实施方法等方面的进展;介绍了3种不同催化剂脱除技术;结合最新的研究成果,着重论述了ATRP在进行聚合物分子设计,制备窄分子量分布聚合物、无规、梯度和交替共聚物,嵌段共聚物,末端官能团聚合物,接枝和梳状聚合物,星型及高支化聚合物等方面的应用。 相似文献
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Primary amine functionalized polystyrenes were prepared in quantitative yields by atom transfer radical polymerization using the adduct of 1‐(bromoethyl)benzene with 1‐(4‐aminophenyl)‐1‐phenylethylene as initiator for styrene polymerization in the presence of a copper(I) bromide/N,N,N′,N′,N″‐pentamethyldiethylenetriamine catalyst system. The polymerizations proceeded via a controlled free radical polymerization process to afford quantitative yields of the corresponding primary amine functionalized polystyrenes with predictable molecular weights (Mn = 2 × 103 to 10 × 103 g mol?1), relatively narrow molecular weight distributions (Mw/Mn = 1.03–1.49), well defined chain‐end functionalities and initiator efficiencies as high as 0.92. The polymerization process was monitored by gas chromatographic analysis. The primary amine functionalized polymers were characterized by thin layer chromatography, size exclusion chromatography, potentiometry and spectroscopy. Experimental results are consistent with quantitative functionalization via the 1,1‐diphenylethylene derivative. Polymerization kinetic measurements show that the polymerization reaction follows first order rate kinetics with respect to monomer consumption and the number average molecular weight increases linearly with monomer conversion. © 2003 Society of Chemical Industry 相似文献
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Jiang Bibiao Yang Yang Deng Jian Fu Shiyang Zhu Rongqi Hao Jianjun Wang Wenyun 《应用聚合物科学杂志》2002,83(10):2114-2123
A cheap acrylic AB* monomer, 2‐(2‐chloroacetyloxy)‐isopropyl acrylate (CAIPA), was prepared from 2‐hydroxyisopropyl acrylate with chloroacetyl chloride in the presence of triethylamine. The self‐condensing vinyl polymerization by atom transfer radical polymerization (ATRP), a “living”/controlled radical polymerization, has yielded hyperbranched polymers. All the polymerization products were characterized by proton nuclear magnetic resonance spectroscopy (1H NMR). CAIPA exhibited distinctive polymerization behavior that is similar to a classical step‐growth polymerization in the relationship of molecular weight to polymerization time, especially during the initial stage of the polymerization. However, a significant amount of monomer remained present throughout the polymerization, which is consistent with typical chain polymerization. Also, if a much longer polymerization time was used, the polymer became gel. As a result of the unequal reactivity of group A* and B*, the polymerization is different from an ideal self‐condensing vinyl polymerization: the branch structures of polymers prepared depend dramatically on the ratio of 2,2'‐bipyridyl to CAIPA. Hyperbranched polymers exhibit improved solubility in organic solvent, however, they have lower thermal stability than their linear analogs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2114–2123, 2002 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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在甲基丙烯酸甲酯(MMA)单体中,以偶氮二异丁腈(AIBN)与I2反应原位合成α-碘代异丁腈(IIBN),进一步作为原子转移自由基聚合引发剂分别与CuCl、FeCl2.4H2O等催化剂,MA5-DETA、PMDETA等络合剂相匹配引发MMA的ATRP,同时又作为衰减链转移聚合(DT)的可逆链转移剂同步进行DT聚合。实验结果表明:所得聚合物分子量可控,分子量分布(PDI)很窄(1.05~1.25),引发剂效率较高。动力学的研究结果显示:分子量随转化率而增长;由Ln[M]0/[M]t对时间作图,呈现良好的线形关系,表明聚合过程中增长自由基浓度是一个恒定值,证明由IIBN引发的聚合是典型的活性自由基聚合;这种方法克服了极不稳定的在α-位带有吸电子基团的碘化物的购运和储存的困难。不失是一种简单,快捷,方便的方法。 相似文献
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Surface modification of various solid polysaccharide substrates was conducted by grafting methyl acrylate (MA) and styrene via atom transfer radical polymerization (ATRP) to produce well‐defined polymer grafts. The hydroxyl groups on the surfaces of the substrates were reacted with 2‐bromoisobutyryl bromide followed by graft copolymerization under ATRP conditions. The studied substrates were filter paper, microcrystalline cellulose, Lyocell fibers, dialysis tubing, and chitosan films. The modified substrates were analyzed by FT‐IR, water contact angle measurements, TGA, and SEM. FT‐IR characterization of the grafted substrates showed significant differences between the different substrates in the amount of grafted polymer. Higher amounts of polymer seem to be possible to graft from native cellulose substrates than from regenerated cellulose substrates. To investigate whether the grafted polymers were “living” after a longer time period, a second layer of polystyrene was grafted from a filter paper modified with PMA one year ago. FT‐IR characterization of the filter paper showed a peak corresponding to styrene, indicating that a block copolymer had been formed on the surface. Graft copolymerization can be used to change and tailor the surface properties of the polysaccharide substrates. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4155–4162, 2006 相似文献
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以自制的双端羟基聚乳酸与α-溴代丙酰溴反应而制得的含溴端基的聚乳酸为大分子引发剂,溴化亚铜/2,2′-联吡啶为催化体系,研究了N-乙烯基吡咯烷酮的原子转移自由基聚合行为,制得了具有两亲性聚乳酸嵌段共聚物。随单体/引发剂摩尔比的增大、聚合温度的升高,共聚物溶液的特性黏度增大,共聚物薄膜的吸水率增加;共聚物在不同降解介质中的降解规律相似,均随降解时间的延长,共聚物薄膜的失重增加,且在不同介质中呈现的降解速率表现为碱液>酸液>水>缓冲液。对聚合物进行了结构表征。 相似文献
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Abstract: Oxyquinolyl end group functionalized PMMA was prepared by
a new initiator 5-chloromethyl-8-hydroxyquinoline via atom
transfer radical polymerization. Studying this polymer, we find
it possesses stronger fluorescence and larger nonlinear
third-order optical (NLO) coefficient than the PMMA initiated by
ethyl -bromoisobutyrate, and the polymer could be easily
processed into film. The NLO coefficient of the polymer tested
in the film is better than that in the solution. 相似文献
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Aniek Sri Handayani Marcelinus Christwardana Athanasia Amanda Septevani 《Polymer-Plastics Technology and Engineering》2020,59(12):1326-1331
ABSTRACTThis study reported the synthesis of macro-initiator based on microfibers cellulose (MFC) from empty bunches (EFB), which was Ethyl α-bromoisobutyrate. The availability of the hydroxyl group on MFC offered a facile functionalization with Ethyl α-bromoisobutyrate to produce Bromo-ester group on MFC surface (MFC-BiB) that are known to be the excellent initiator for atom transfer radical polymerization (ATRP). As MFC provides only three hydroxyl groups per each unit of glucose with low reactivity, it is crucial to modify MFC with bromide functional groups having reactivity about 10.000 times greater than the hydroxyl group in the MFC. An MFC-BiB macro-initiator was successfully synthesized by homogeneous acetylation of cellulose with Ethyl α-bromoisobutyrate (EBiB) at 40°C. To confirm the performance MFC-BiB as macroinitiator, copolymerization between latex and MFC-BiB was conducted to produce Cellulose-g-latex by ATRP method with bipyridine/CuCl/CuCl2 ligand as a complex catalyst and toluene/water as a mixed solvent. The degree of MFC-BiB substitution was measured by the FTIR method. The grafting copolymers were characterized by H-NMR and FTIR. The results indicated that the degree of substitution of macro-initiator at the ratio of MFC/EBiB of 1:3 and 1:6 were 1.27 and 1.28, respectively. The grafting efficiency of cellulose backbone with latex via ATRP showed a well-controlled grafting reaction at 44.5%. 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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Qiang Yu Zhongqiong Qin Jinchun Li Shiping Zhu 《Polymer Engineering and Science》2008,48(7):1254-1260
The reaction behavior of atom transfer radical polymerization (ATRP) with crosslinking was studied using di(meth)acrylates as the model network‐forming system. The kinetics was followed by differential scanning calorimetry (DSC). The structural evolution of the networks was investigated by gel permeation chromatography (GPC) and extraction/swelling measurements. The linear primary chains were obtained by hydrolysis of the networks and analyzed by viscometry. It was found that the polymerization proceeded in a controlled/living manner in an early stage of the reaction with the molecular weight of primary chains increasing linearly with vinyl conversion. However, deviations from the linearity occurred at high monomer conversions due to the network structure that severely restricted mobilities of catalyst/ligand complexes in the radical activation/deactivation. The onset and degree of deviation depended on crosslinking density. The diffusion‐controlled radical deactivation caused a mild autoacceleration in the polymerization rate. Adding excess Cu(II) to the system reduced the polymerization rate but improved the linear growth of primary chains that would facilitate the synthesis of networks of controlled microstructure. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers 相似文献
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采用水杨醛和二乙烯三胺反应合成用于原子转移自由基聚合的新型配体——N-水杨醛缩二乙烯三胺,通过元素分析和核磁共振表征N-水杨醛缩二乙烯三胺,以乙-溴代丙酸乙酯(EBP)为引发剂,用N-水杨醛缩二乙烯三胺催化合成聚甲基丙烯酸甲酯(PMMA),并采用凝胶渗透色谱(GPC)测其相对分子质量及其分布,考察聚合体系的动力学.结果表明:甲基丙烯酸甲酯(MMA)/EBP/溴化亚铜/N-水杨醛缩二乙烯三胺体系和MMA/EBP/溴化亚铜/N-水杨醛缩二乙烯三胺/N,N-二甲基甲酰胺(DMF)体系的原子转移自由基聚合符合一级动力学规律,且具有"活性"和可控性,相对分子质量分布较窄(前者为1.46,后者为1.34),加入溶剂后,催化活性和自由基浓度均有所下降. 相似文献