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1.
Graft copolymers prepared by atom transfer radical polymerization (ATRP) from cellulose 总被引:2,自引:0,他引:2
A cellulose-based macro-initiator, cellulose 2-bromoisobutyrylate, for atom transfer radical polymerization (ATRP) was successfully synthesized by direct homogeneous acylation of cellulose in a room temperature ionic liquid, 1-allyl-3-methylimidazolium chloride, without using any catalysts and protecting group chemistry. ATRP of methyl methacrylate and styrene from the macro-initiator was then carried out. The synthesized cellulose graft copolymers were characterized by FTIR, 1H NMR and 13C NMR spectroscopies. The grafted PMMA and PS chains were obtained by the hydrolysis of the cellulose backbone and analyzed by GPC. The results obtained from these analytical techniques confirm that the graft polymerization occurred from the cellulose backbone and the obtained copolymers had grafted polymer chains with well-controlled molecular weight and polydispersity. Through static and dynamic laser light scattering and TEM measurements, it was found that the cellulose graft copolymer in solution could aggregate and self-assembly into sphere-like polymeric structure. 相似文献
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A series of well-defined brush-type amphiphilic polystyrene-g-poly(2-(dimethylamino) ethyl methacrylate)) (PS-g-PDMAEMA) copolymers were successfully synthesized via atom transfer radical polymerization (ATRP), using chloromethylated polystyrene (CMPS) as the macroinitiator. The self-assembly behavior of the resulting brush-type copolymers in deionized water and deionized water/acetone (v/v=2/3) mixture was studied by high performance particle sizer (HPPS). The results showed that the Z-average size of the micelles in deionized water increased with the increase of molecular weight of PDMAEMA, and the corresponding size was larger than that in mixed solvent of deionized water and acetone (v/v=2/3). The morphologies of the micelles self-assembled from PS-g-PDMAEMA in selective solvents were studied by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). When the micelles were prepared in water/acetone (v/v=2/3) mixture and cast them on a glass slide at different temperatures (from 50 up to 200 °C), the transformation of the morphologies of aggregates, from needle-like solid to microcubic particles, was observed using SEM. 相似文献
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At room temperature atom transfer radical polymerization (ATRP) of N-vinylpyrrolidone (NVP) was carried out using 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetra-azacyclo-tetradecane (Me6Cyclam) as ligand in 1,4-dioxane/isopropanol mixture. Methyl 2-chloropropionate (MCP) and copper(I) chloride were used as initiator and catalyst, respectively. The polymerization of NVP via ATRP could be mediated by the addition of CuCl2. The resultant poly(N-vinylpyrrolidone) (PNVP) has high conversion of up to 65% in 3 h, a controlled molecular weight close to the theoretical values and narrow molecular weight distribution between 1.2 and 1.3. The living nature of the ATRP for NVP was confirmed by the experiments of PNVP chain extension. With PNVP-Cl as macroinitiator and N-methacryloyl-N′-(α-naphthyl)thiourea (MANTU) as a hydrophobic monomer, novel fluorescent amphiphilic copolymers poly(N-vinylpyrrolidone)-b-poly(N-methacryloyl-N′-(α-naphthyl)thiourea) (PNVP-b-PMANTU) were synthesized by ATRP. PNVP-b-PMANTU copolymers were characterized by 1H NMR, GPC-MALLS and fluorescence measurements. The results revealed that PNVP-b-PMANTU presented a blocky architecture. 相似文献
5.
Uma Chatterjee 《Polymer》2005,46(24):10699-10708
Amphiphilic di- and tri-block copolymers of poly(methyl methacrylate) (PMMA) and poly(2-dimethylamino)ethyl methacrylate (PDMAEMA) have been synthesized by atom transfer radical polymerization (ATRP) at ambient temperature (35 °C) in the environment-friendly solvent, aqueous ethanol (water 16 vol%) using CuCl/o-phenanthroline as the catalyst. The PDMAEMA blocks are contaminated with ethyl methacrylate (EMA) residues to the extent of 1-2 mol% of DMAEMA depending on the length of the PDMAEMA block. The EMA forms through the autocatalyzed ethanolysis of the DMAEMA monomer and undergoes random copolymerization with the latter. The rate of ethanolysis is unexpectedly greater in the aqueous ethanol than in neat ethanol, which has been attributed to the higher polarity of the former than of the latter. In contrast to the ethanolysis no hydrolysis of DMAEMA in the aqueous ethanol medium could be detected for 133 h. The block copolymers form micelles in water. Their solubility and CMC in neutral water have been studied. Dynamic light scattering (DLS) studies reveal that for a fixed degree of polymerization (DP) of the PMMA block the hydrodynamic diameter of the micelles in methanolic water (water 95 vol%) increases at a faster rate with the DP of the PDMAEMA block when it is much greater than that of the PMMA block compared to when it is less than or close to that of the latter. 相似文献
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Amphiphilic ABA triblock copolymers of poly(ethylene oxide) (PEO) with methyl methacrylate (MMA) were prepared by atom transfer radical polymerization in bulk and in various solvents with a difunctional PEO macroinitiator and a Cu(I)X/N,N,N′,N″,N″‐pentamethyldiethylenetriamine catalyst system at 85°C where X=Cl or Br. The polymerization proceeded via controlled/living process, and the molecular weights of the obtained block copolymers increased linearly with monomer conversion. In the process, the polydispersity decreased and finally reached a value of less than 1.3. The polymerization followed first‐order kinetics with respect to monomer concentration, and increases in the ethylene oxide repeating units or chain length in the macroinitiator decreased the rate of polymerization. The rate of polymerization of MMA with the PEO chloro macroinitiator and CuCl proceeded at approximately half the rate of bromo analogs. A faster rate of polymerization and controlled molecular weights with lower polydispersities were observed in bulk polymerization compared with polar and nonpolar solvent systems. In the bulk polymerization, the number‐average molecular weight by gel permeation chromatography (Mn,GPC) values were very close to the theoretical line, whereas lower than the theoretical line were observed in solution polymerizations. The macroinitiator and their block copolymers were characterized by Fourier transform infrared spectroscopy, 1H‐NMR, matrix‐assisted laser desorption ionization time‐of‐flight mass spectrometry, thermogravimetry (TG)/differential thermal analysis (DTA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). TG/DTA studies of the homo and block copolymers showed two‐step and multistep decomposition patterns. The DSC thermograms exhibited two glass‐transition temperatures at ?17.7 and 92°C for the PEO and poly(methyl methacrylate) (PMMA) blocks, respectively, which indicated that microphase separation between the PEO and PMMA domains. SEM studies indicated a fine dispersion of PEO in the PMMA matrix. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 989–1000, 2005 相似文献
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Reverse atom transfer radical polymerization (RATRP) of styrene (S) was carried out in bulk using polyazoester prepared by
the reaction of polyethylene glycol with molecular weight of 3000 and 4,4′-azobis(4-cyanopentanoyl chloride) as initiator
and CuCl2/2,2′-bipyridine (bpy) catalyst system to yield poly(ethylene glycol-b-styrene) block copolymer. The block copolymers were
characterized 1H NMR, FT-IR spectroscopy and GPC. The 1H NMR, and FT-IR spectra showed that formation of poly(ethylene glycol-b-styrene) block copolymer. The polydispersities of
block copolymers were observed between from 1.49 and 1.98 GPC measurements. 相似文献
8.
Atom transfer radical polymerization (ATRP) of 1‐(butoxy)ethyl methacrylate (BEMA) was carried out using CuBr/2,2′‐bipyridyl complex as catalyst and 2‐bromo‐2‐methyl‐propionic acid ester as initiator. The number average molecular weight of the obtained polymers increased with monomer conversion, and molecular weight distributions were unimodal throughout the reaction and shifted toward higher molecular weights. Using poly(methyl methacrylate) (PMMA) with a bromine atom at the chain end, which was prepared by ATRP, as the macro‐initiator, a diblock copolymer PMMA‐block‐poly [1‐(butoxy)ethyl methacrylate] (PMMA‐b‐PBEMA) has been synthesized by means of ATRP of BEMA. The amphiphilic diblock copolymer PMMA‐block‐poly(methacrylic acid) can be further obtained very easily by hydrolysis of PMMA‐b‐PBEMA under mild acidic conditions. The molecular weight and the structure of the above‐mentioned polymers were characterized with gel permeation chromatography, infrared spectroscopy and nuclear magnetic resonance. Copyright © 2005 Society of Chemical Industry 相似文献
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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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In order to prepare well-defined pH-sensitive block copolymers with a narrow molecular weight distribution (MWD), we synthesized a pH-sensitive block copolymer via atom transfer radical polymerization (ATRP) of sulfamethazine methacrylate monomer (SM) and amphiphilic diblock copolymers by the ring-opening polymerization of d,l-lactide/?-caprolactone (LA/CL), and their sol-gel phase transition was investigated. SM, which is a derivative of sulfonamide, was used as a pH responsive moiety, while PCLA-PEG-PCLA was used as a biodegradable, as well as a temperature sensitive one, amphiphilic triblock copolymer. The pentablock copolymer, OSM-PCLA-PEG-PCLA-OSM, was synthesized using Br-PCLA-PEG-PCLA-Br as an ATRP macroinitiator. The number average molecular weights of SM were controlled by adjusting the monomer/initiator feed ratio. The macroinitiator was synthesized by the coupling of 2-bromoisobutyryl bromide with PCLA-PEG-PCLA in the presence of triethyl amine catalyst in dichloromethane. The resultant block copolymer shows a narrow polydispersity. The block copolymer solution shows a sol-gel transition in response to a slight pH change in the range of 7.2-8.0. Gel permeation chromatography (GPC) and NMR were used for the characterization of the polymers that were synthesized. 相似文献
12.
Atom transfer radical polymerization (ATRP) of styrene and acrylonitrile with monofunctional and bifunctional initiators 总被引:1,自引:0,他引:1
Mamdouh Al-Harthi 《Polymer》2007,48(7):1954-1961
A bifunctional initiator (benzal bromide) was used to initiate the bulk atom transfer radical polymerization of styrene and acrylonitrile at 90 °C with CuBr/2,2-bipyridyl. We compared these results with those of a monofunctional initiator of similar structure (1-bromoethyl benzene) under the same polymerization conditions. The monofunctional initiator worked better than the bifunctional initiator when both comonomers were added simultaneously at the beginning of the copolymerization; the bifunctional initiator was only effective when acrylonitrile was added after 20 min of polymerization with styrene. The styrene-acrylonitrile copolymers were characterized by gel permeation chromatography, 13C nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, and refractometry. Copolymer composition was monitored by both 13C NMR and by the change in the specific refractive index increment. 相似文献
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A novel amphiphilic phosphorus-containing polymer was prepared by RAFT polymerization of 3-[2-(acryloyloxy)ethoxy]-3-oxopropyl(phenyl) phosphinic acid (AOPA). The monomer was first synthesized by esterification of 3-[hydroxy(phenyl)phosphoryl]propanoic acid and 2-hydroxyethyl acrylate, and then the polymerizations were performed at 60 °C. The polymerization was well controlled, and the polymers with “well-defined” structures were successfully synthesized. The polymers can self-assemble to form the micelles in distilled water due to the special amphiphilic structure, and the shell of the micelles could be cross-linked by the coordination of phosphinic acid with cations. The property may promote the polymers to be used in the ionic exchange for the environment protection. 相似文献
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The polymerization by ATRP of hydroxy and amino functional acrylates and methacrylates with tert-butyldimethylsilyl (TBDMS) or tert-butyloxycarbonyl (BOC) protective groups has been studied for the first time achieving high control over molecular weight and polydispersity. Detailed investigation of the ATRP of 2-{[tert-butyl(dimethyl)silyl]oxy}ethyl acrylate (M2b) in bulk and 2-[(tert-butoxycarbonyl)amino]ethyl 2-methylacrylate (M3a) in diphenyl ether (DPE) showed that the type of ligand plays an important role on either the polymerization rate or the degree of control of the polymerization. Among the ligands used, N,N,N,′N″N″-pentamethyl diethylenetriamine (PMDETA) was the most suitable ligand for ATRP of all functional acrylates and methacrylates. The kinetics of M2b and M3a polymerization using PMDETA as a ligand was reported and proved the living character of the polymerization. Well-defined block copolymers based on a halogen terminated polystyrene (Pst) macroinitiator and the functional acrylate and methacrylate monomers were successfully synthesized by ATRP, and subsequent deprotection of the protective groups from the acrylate or methacrylate segment afforded amphiphilic block copolymers with a specific solubility behavior. 相似文献
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This review covers both fundamental aspects and applications of electrochemically mediated atom transfer radical polymerization (eATRP). eATRP setup is discussed in detail, together with the advantages and limitations of this technique. All relevant parameters that can influence eATRP outcome are evaluated (e.g. applied current and potential, stirring and diffusion, solvents and supporting electrolytes). Various materials prepared by eATRP are described, including homopolymers, block copolymers, star polymers, and surface grafted polymer brushes. In addition, other electrochemical techniques conceptually similar to eATRP are discussed, including copper-catalyzed azide-alkyne cycloaddition, electrochemical micropatterning, reversible addition-fragmentation chain transfer polymerization using redox-sensitive initiators, and catalyst removal by electrochemical reduction. The increasing research activity in the last decade indicates that electrochemically regulated methods are becoming valuable tools in the design and synthesis of advanced polymer materials. 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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Recent progress in controlled radical polymerizations, in particular atom transfer radical polymerization (ATRP), has provided a unique means for the design and synthesis of bioactive surfaces and functional biomaterials. This review summarizes such recent research activities. The synthesis strategies of bioactive surfaces and biomaterials via ATRP are described in detail. The highly robust and versatile ATRP technique is particularly suited for the preparation of functional bioactive surfaces, including antifouling, antibacterial, stimuli-responsive, biomolecule-coupled and micropatterned surfaces. In addition to bioactive surfaces, ATRP has also been widely used for the preparation of well-structured functional biomaterials, such as micellar delivery systems, hydrogels, cationic gene carriers and polymer–protein conjugates. The research activities in the last decade indicate that ATRP has become an essential tool for the design and synthesis of advanced, noble and novel biomaterials. 相似文献
19.
Bohumil Masa Miroslav Janata Petra Ltalov Milo Netopilík Petr Vl
ek Ludk Toman 《应用聚合物科学杂志》2006,100(5):3662-3672
Grafting of tert‐butyl acrylate (tBuA), methyl methacrylate (MMA), and styrene (St) monomers (M) by Cu(I)‐mediated ATRP from polystyrene (PSt) macroinitiator (Mn = 5620, polydispersity index, PDI = 1.12), containing initiating 2‐bromopropionyloxy groups (I) (bound to 34% of aromatic cores; 11 groups per backbone), was performed using conditions suitable for the respective homopolymerizations. The preparation of PSt‐g‐PtBuA in bulk using an initial molar ratio [M]0/[I]0 = 140 had a controlled character up to Mn = (132–148) × 103 (PDI = 1.08–1.16). With MMA and St and using the same [M]0/[I]0, preliminary experiments were made; the higher the monomer conversion, the broader was the distribution of molecular weight of the products. Graft copolymerizations of all these monomers at [M]0/[I]0 = 840 or 1680 were successfully conducted up to high conversions. Low‐polydispersity copolymers, with very long side chains, in fact star‐like copolymers, were obtained mainly by tuning the deactivator amount in the reaction mixture. (PSt‐g‐PtBuA, DPn,sc (DP of side chain) = 665, PDI = 1.24; PSt‐g‐PMMA, DPn,sc = 670, PDI = 1.43; PSt‐g‐PSt, DPn,sc = 324, PDI = 1.11). Total suppression of intermolecular coupling was achieved here. However, the low concentrations of initiator required long reaction times, leading sometimes to formation of a small amount (~5%) of low‐molecular‐weight polymer fraction. This concomitant process is discussed, and some measures for its prevention are proposed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 3662–3672, 2006 相似文献
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This article reports on a facile route for the preparation of methyl acrylate and methyl methacrylate graft copolymers via a combination of catalytic olefin copolymerization and atom transfer radical polymerization (ATRP). The chemistry first involved a transforming process from ethylene/allylbenzene copolymers to a polyolefin multifunctional macroinitiator with pendant sulfonyl chloride groups. The key to the success of the graft copolymerization was ascribed to a fast exchange rate between the dormant species and active radical species by optimization of the various experimental parameters. Polyolefin‐g‐poly(methyl methacrylate) and polyolefin‐g‐poly(methyl acrylate) graft copolymers with controlled architecture and various graft lengths were, thus, successfully prepared under dilute ATRP conditions. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献