共查询到20条相似文献,搜索用时 11 毫秒
1.
Sinoj Abraham Chang‐Sik Ha Il Kim 《Journal of polymer science. Part A, Polymer chemistry》2005,43(24):6367-6378
A series of poly(styrene‐block‐tert‐butyl acrylate) heteroatom star block copolymers having various block lengths were prepared by atom transfer radical polymerization (ATRP), using an “as synthesized” cynurate modified trifunctional initiator. The structure of the star polymers was confirmed by the characterization of the individual arms resulting from hydrolysis. Amphiphilic poly(styrene‐block‐acrylic acid) star copolymers were further synthesized by hydrolyzing PtBA blocks using anhydrous trifluoroacetic acid. The characterization data are reported from analyses using gel permeation chromatography, infrared, 1H and 13C NMR spectroscopies. The stable micelle solution was prepared by dialyzing the solution of these polymers in N,N‐dimethylformamide against deionized water. The temperature‐induced associating behavior of these amphiphilic star polymers were studied using dynamic laser light scattering spectroscopy. The hydrodynamic diameter of both micelles and unassociated chains were obtained in the same solution using light scattering cumulant's calculation method. The homogeneity and the size distribution of the micelle population in the solution were determined using centrifuge/sedimentation particle size distribution analyzer. Field emission scanning electron microscope was used to visualize the size of the micelles formed and the micellar aggregates. The influence of the temperature on the viscosity of the micelle solution was studied using an Ubbelohde viscometer. Thermodynamics of micellization of these block copolymers were also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 6367–6378, 2005 相似文献
2.
Atanu Kuila Dhruba P. Chatterjee Rama K. Layek Arun K. Nandi 《Journal of polymer science. Part A, Polymer chemistry》2014,52(7):995-1008
A new “grafting from” strategy for grafting of different monomers (methacrylates, acrylates, and acrylamide) on poly(vinylidene fluoride) (PVDF) backbone is designed using atom transfer radical coupling (ATRC) and atom transfer radical polymerization (ATRP). 4‐Hydroxy TEMPO moieties are anchored on PVDF backbone by ATRC followed by attachment of ATRP initiating sites chosen according to the reactivity of different monomers. High graft conversion is achieved and grafting of poly(methyl methacrylate) (PMMA) exhibits high degree of polymerization (DPn = 770) with a very low graft density (0.18 per hundred VDF units) which has been increased to 0.44 by regenerating the active catalyst with the addition of Cu(0). A significant impact on thermal and stress–strain property of graft copolymers on the graft density and graft length is noted. Higher tensile strain and toughness are observed for PVDF‐g‐PMMA produced from model initiator but graft copolymer from pure PVDF exhibits higher tensile strength and Young's modulus. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 995–1008 相似文献
3.
Haimanti Datta Anil K. Bhowmick Nikhil K. Singha 《Journal of polymer science. Part A, Polymer chemistry》2008,46(15):5014-5027
Hybrid nanoarchitecture of tailor‐made Poly(ethyl acrylate)/clay was prepared by surface‐initiated atom transfer radical polymerization (SI‐ATRP), by tethering ATRP initiator on active hydroxyl group, present in surface as well as in the organic modifier of the clay used. Extensive exfoliation was facilitated by using these initiator modified clay platelets. Poly(ethyl acrylate) chains with controlled polymerization and narrow polydispersities were forced to be grown from within the clay gallery (intergallery) as well as from the outer surface (extragallery) of the clay platelets. The polymer chains attached onto clay surfaces might have the potential to provide the composites with enhanced compatibility in blends with common polymers. Attachment of the initiator on clay platelets was confirmed by Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), elemental analysis, Wide‐angle X‐ray diffraction (WAXD), and microscopic analysis. Finally, end group analysis (by Matrix‐Assisted Laser Desorption Ionization Mass Spectrometry, and chain extension experiment) of the cleaved polymer and morphological study (by WAXD, Transmission Electron Microscopy), performed on the polymer grafted clays examined the effect of grafting on the efficiency of polymerization and the degree of dispersion of clay tactoids in polymer. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5014–5027, 2008 相似文献
4.
A. S. Brar Sukhdeep Kaur 《Journal of polymer science. Part A, Polymer chemistry》2005,43(5):1100-1118
Copolymers of methyl methacrylate (MMA) and n‐butyl acrylate (n‐BA) were synthesized under atom transfer radical polymerization (ATRP) conditions. The molar infeed ratio was varied to obtain copolymers with different compositions. Methyl 2‐bromo propionate was used as the initiator with CuBr/Cu(0)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalyst at 60 °C. Molecular weight distribution was determined by gel permeation chromatography (GPC). Copolymer compositions (FM) were calculated from 1H NMR spectra. Reactivity ratios calculated with the Mao–Huglin terminal model at a high conversion were found to be rM = 2.17 and rB = 0.47. The polymerization mechanism was studied with the α‐methyl region of MMA. The backbone methylene and carbonyl carbons of both MMA and n‐BA units were found to be compositionally as well as configurationally sensitive. Complete spectral assignments were performed with the help of heteronuclear single quantum coherence (HSQC) spectroscopy along with total correlated spectroscopy (TOCSY). Further, the assignments of the carbonyl region were made with the help of heteronuclear multiple quantum coherence (HMBC) spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1100–1118, 2005 相似文献
5.
I. Garcia N. E. Zafeiropoulos A. Janke A. Tercjak A. Eceiza M. Stamm I. Mondragon 《Journal of polymer science. Part A, Polymer chemistry》2007,45(5):925-932
A key problem with nanomaterials is the difficulty of controlling the dispersion of nanoparticles inside an organic medium. To overcome this problem, functionalization of the nanoparticle surface is required. Poly(methyl methacrylate) (PMMA) brushes were grown on the surface of iron oxide magnetic nanoparticles with atom transfer radical polymerization and a grafting‐from approach. Modified magnetic nanoparticles with a graft density of 0.1 PMMA chains/nm2 were obtained. Cu(II), used as a deactivating complex, allowed good control of the polymerization along with a narrow polydispersity of the polymer chains. The functionalized magnetic nanoparticles were characterized with Fourier transform infrared spectroscopy, thermogravimetric analysis, gel permeation chromatography, and atomic force microscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 925–932, 2007 相似文献
6.
Auke Snijder Bert Klumperman Rob Van Der Linde 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2350-2359
The introduction of a functional group into a poly(butyl acrylate) polymer prepared by copper‐mediated atom transfer radical polymerization and the characterization of the prepared polymer by gradient polymer elution chromatography are reported. The bromo end group of the initial polymer can be transformed into a different functional group with several functionalization reactions, including nucleophilic substitution and atom transfer radical addition (ATRA), in combination with comonomers, addition–fragmentation transfer agents, or stable radicals. Several new functionalization agents are reported, including ATRA using 1‐(3‐hydroxymethyl‐phenyl)‐pyrrole‐2,5‐dione and trimethyl{1‐[4‐(2‐trimethylsiloxyethoxy)]phenylethenyloxy}silane and nucleophilic substitution using 2‐mercapto ethanol. The rate constant of the functionalization reaction and the final functionality are determined with gradient polymer elution chromatography, a technique by which qualitative and quantitative information about the conversion can be obtained. Polymers with a functionality greater than 95% are reported. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2350–2359, 2002 相似文献
7.
Haimanti Datta Anil K. Bhowmick Nikhil K. Singha 《Journal of polymer science. Part A, Polymer chemistry》2007,45(9):1661-1669
Atom transfer radical polymerization (ATRP) of ethyl acrylate (EA) was carried out using different initiators, CuBr or CuCl as catalyst in combination with different ligands e.g., 2,2′‐bipyridine (bpy) and N,N,N′,N″N″‐pentamethyl diethylenetriamine (PMDETA). Use of PMDETA as ligand resulted in faster polymerization rate (95% conversion in 15 min) than those using bipyridine (~58% conversion in 10.5 h). This is due to the lower reduction potential of copper‐amine than that of copper‐bpy complex, resulting in higher rates of activation of dormant halides. Use of ethylene carbonate as solvent lead to faster polymerization rate and better control in polymerization when compared with p‐xylene as solvent. The reaction temperature had a positive effect on polymerization rate and the optimum reaction temperature was found to be 90 °C. An apparent enthalpy of activation of ~85 kJ/mol was determined for the ATRP of ethyl acrylate, corresponding to an enthalpy of equilibrium of ~64 kJ/mol. By judicious choice of the reaction parameters it was possible to tailor the end group of the final polymer. MALDI‐TOF‐MS analysis and the chain extension experiment of poly(ethyl acrylate) (PEA) prepared using bpy as ligand showed the presence of ? Br as the end group. On the contrary, when PMDETA was used as the ligand, the mass spectra analysis showed hydrogen terminated polymer as the major species towards the end of polymerization. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1661–1669, 2007 相似文献
8.
Kelly A. Davis Bernadette Charleux Krzysztof Matyjaszewski 《Journal of polymer science. Part A, Polymer chemistry》2000,38(12):2274-2283
Block copolymers of polystyrene and poly(t‐butyl acrylate) were prepared using atom transfer radical polymerization techniques. These polymers were synthesized with a CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine catalyst system and had predictable molecular weights based on the degree of polymerization, as calculated from the initial ratio of monomer to initiator. The final polydispersities were low (1.10 < Mw /Mn < 1.3) for all the homopolymers and block copolymers. Polymers of various chain architectures were prepared, ranging from linear AB diblocks to three‐armed stars composed of AB diblocks on each arm. The key to controlled synthesis with this catalyst system was the choice of the solvent, temperature, and concentrations of catalyst and deactivator. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2274–2283, 2000 相似文献
9.
Sung Chul Hong Shijun Jia Mircea Teodorescu Tomasz Kowalewski Krzysztof Matyjaszewski Amy C. Gottfried Maurice Brookhart 《Journal of polymer science. Part A, Polymer chemistry》2002,40(16):2736-2749
Poly(n‐butyl acrylate)‐graft‐branched polyethylene was successfully prepared by the combination of two living polymerization techniques. First, a branched polyethylene macromonomer with a methacrylate‐functionalized end group was prepared by Pd‐mediated living olefin polymerization. The macromonomer was then copolymerized with n‐butyl acrylate by atom transfer radical polymerization. Gel permeation chromatography traces of the graft copolymers showed narrow molecular weight distributions indicative of a controlled reaction. At low macromonomer concentrations corresponding to low viscosities, the reactivity ratios of the macromonomer to n‐butyl acrylate were similar to those for methyl methacrylate to n‐butyl acrylate. However, the increased viscosity of the reaction solution resulting from increased macromonomer concentrations caused a lowering of the apparent reactivity ratio of the macromonomer to n‐butyl acrylate, indicating an incompatibility between nonpolar polyethylene segments and a polar poly(n‐butyl acrylate) backbone. The incompatibility was more pronounced in the solid state, exhibiting cylindrical nanoscale morphology as a result of microphase separation, as observed by atomic force microscopy. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2736–2749, 2002 相似文献
10.
Yan Shi Zhifeng Fu Bingyi Li Wantai Yang 《Journal of polymer science. Part A, Polymer chemistry》2006,44(8):2468-2475
A stable nitroxyl radical functionalized with an initiating group for atom transfer radical polymerization (ATRP), 4‐(2‐bromo‐2‐methylpropionyloxy)‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy (Br‐TEMPO), was synthesized by the reaction of 4‐hydroxyl‐2,2,6,6‐tetramethyl‐1‐piperidinyloxy with 2‐bromo‐2‐methylpropionyl bromide. Stable free radical polymerization of styrene was then carried out using a conventional thermal initiator, dibenzoyl peroxide, along with Br‐TEMPO. The obtained polystyrene had an active bromine atom for ATRP at the ω‐end of the chain and was used as the macroinitiator for ATRP of methyl acrylate and ethyl acrylate to prepare block copolymers. The molecular weights of the resulting block copolymers at different monomer conversions shifted to higher molecular weights and increased with monomer conversion. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2468–2475, 2006 相似文献
11.
Niyazi Bicak Mesut Ozlem 《Journal of polymer science. Part A, Polymer chemistry》2003,41(21):3457-3462
Trace amounts of labile chlorines present in poly(vinyl chloride) (PVC) were found to act as initiation sites for the preparation of graft copolymers of PVC by copper‐mediated atom transfer radical polymerization (ATRP). High grafting yields were attained during the graft copolymerizations of n‐butyl acrylate (161.8%) and 2‐ethyl hexyl acrylate (51.2%) in 7.5 h. In both cases, the grafting proceeded with first‐order kinetics with respect to the monomer concentrations, this being typical for ATRP. Gel permeation chromatography traces of the resulting products did not exhibit additional peaks attributable to the formation of free homopolymers. The presented procedure offers an efficient means of preparing self‐plasticized PVC structures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3457–3462, 2003 相似文献
12.
Synthesis of poly(2‐ethylhexyl acrylate)/clay nanocomposite by in situ living radical polymerization
Dhruba J. Haloi Nikhil K. Singha 《Journal of polymer science. Part A, Polymer chemistry》2011,49(7):1564-1571
This investigation reports the preparation of tailor‐made poly(2‐ethylhexyl acrylate) (PEHA) prepared via in situ living radical polymerization in the presence of layered silicates and characterization of this polymer/clay nanocomposite. Being a low Tg (?65 °C) material, PEHA has very good film formation property for which it is used in paints, adhesives, and coating applications. 2‐Ethylhexyl acrylate was polymerized at 90 °C using CuBr and Cu(0) as catalyst in combination with N,N,N′,N″,N″‐pentamethyl diethylenetriamine (PMDETA) as ligand. A tremendous enhancement in reaction rate and polymerization data was achieved when acetone was added as additive to increase the efficiency of the catalyst system. PEHA/clay nanocomposite was prepared at 90 °C using CuBr as catalyst in combination with PMDETA as ligand. Different types of clay with same loading were also used to study the effect on reaction rate. The molecular weight (Mn) and polydispersity index of the prepared nanocomposites were characterized by size exclusion chromatography. The active end group of the polymer chain was analyzed by 1H NMR analysis and by chain extension experiment. Polymer/clay interaction was studied by Fourier Transform Infrared spectrometry and wide‐angle X‐ray diffraction analyses. Distribution of clay in the polymer matrix was studied by the transmission electron microscopy. Thermogravimetric analysis showed that thermal stability of PEHA/clay nanocomposite increases on addition of nanoclay. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
13.
Belkacem Otazaghine Cyrille Boyer Jean‐Jacques Robin Bernard Boutevin 《Journal of polymer science. Part A, Polymer chemistry》2005,43(11):2377-2394
Different acrylate oligomers were synthesized by atom transfer radical polymerization in the presence of a transfer agent and CuBr/1,1,4,7,10,10‐hexamethyltriethylenetetramine. The functionality in bromine was determined by 1H NMR. These oligomers were coupled in the presence of Cu(0) and the ligand 2,2′‐bipyridine. The coupling yield was determined by size exclusion chromatography and NMR analysis and depended on the nature of the monomer and not on the molecular weight. In other words, the preliminary functionalization of the brominated chain end with styrene increased the coupling yield. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2377‐2394, 2005 相似文献
14.
Will R. Gutekunst Athina Anastasaki Sungbaek Seo Alaina J. McGrath David J. Lunn Paul G. Clark Craig J. Hawker 《Journal of polymer science. Part A, Polymer chemistry》2017,55(5):801-807
A new di‐tert‐butyl acrylate (diTBA) monomer for controlled radical polymerization is reported. This monomer complements the classical use of tert‐butyl acrylate (TBA) for synthesis of poly(acrylic acid) by increasing the density of carboxylic acids per repeat unit, while also increasing the flexibility of the carboxylic acid side‐chains. The monomer is well behaved under Cu(II)‐mediated photoinduced controlled radical polymerization and delivers polymers with excellent chain‐end fidelity at high monomer conversions. Importantly, this new diTBA monomer readily copolymerizes with TBA to further the potential for applications in areas such as dispersing agents and adsorbents. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 801–807 相似文献
15.
G. Carrot S. Diamanti M. Manuszak B. Charleux J.‐P. Vairon 《Journal of polymer science. Part A, Polymer chemistry》2001,39(24):4294-4301
This article reports the synthesis of atom transfer radical polymerization (ATRP) of active initiators from well‐defined silica nanoparticles and the use of these ATRP initiators in the grafting of poly(n‐butyl acrylate) from the silica particle surface. ATRP does not require difficult synthetic conditions, and the process can be carried out in standard solvents in which the nanoparticles are suspended. This “grafting from” method ensures the covalent binding of all polymer chains to the nanoparticles because polymerization is initiated from moieties previously bound to the surface. Model reactions were first carried out to account for possible polymerization in diluted conditions as it was required to ensure the suspension stability. The use of n‐butyl acrylate as the monomer permits one to obtain nanocomposites with a hard core and a soft shell where film formation is facilitated. Characterization of the polymer‐grafted silica was done from NMR and Fourier transform infrared spectroscopies, dynamic light scattering, and DSC. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 4294–4301, 2001 相似文献
16.
Jong‐Bum Kim Wenxi Huang Matthew D. Miller Gregory L. Baker Merlin L. Bruening 《Journal of polymer science. Part A, Polymer chemistry》2003,41(3):386-394
Although atom transfer radical polymerization (ATRP) is often a controlled/living process, the growth rate of polymer films during surface‐initiated ATRP frequently decreases with time. This article investigates the mechanism behind the termination of film growth. Studies of methyl methacrylate and methyl acrylate polymerization with a Cu/tris[2‐(dimethylamino)ethyl]amine catalyst system show a constant but slow growth rate at low catalyst concentrations and rapid growth followed by early termination at higher catalyst concentrations. For a given polymerization time, there is, therefore, an optimum intermediate catalyst concentration for achieving maximum film thickness. Simulations of polymerization that consider activation, deactivation, and termination show trends similar to those of the experimental data, and the addition of Cu(II) to polymerization solutions results in a more constant rate of film growth by decreasing the concentration of radicals on the surface. Taken together, these studies suggest that at high concentrations of radicals, termination of polymerization by radical recombination limits film growth. Interestingly, stirring of polymerization solutions decreases film thickness in some cases, presumably because chain motion facilitates radical recombination. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 386–394, 2003 相似文献
17.
Leong‐Huat Gan Palaniswamy Ravi Bao Wei Mao Kam‐Chiu Tam 《Journal of polymer science. Part A, Polymer chemistry》2003,41(17):2688-2695
Polymerization of 2‐(diethylamino)ethyl methacrylate (DEAEMA) via homogeneous atom transfer radical polymerization under various reaction conditions is described. The effects of the initiators and solvents were examined. With 1,1,4,7,10,10‐hexamethyl triethylenetetramine/copper(I) chloride/p‐toluenesulfonyl chloride as the ligand/catalyst/initiator system in methanol, poly(DEAEMA) with a polydispersity index as low as 1.07 was synthesized. Kinetic studies demonstrated the polymerization was very well controlled and exhibited the living characteristic of the process. Well‐defined block copolymers of DEAEMA and tert‐butyl methacrylate (tBMA) were successfully synthesized. The copolymers could be synthesized with equally good results by starting with either p(DEAEMA) or p(tBMA) as the macroinitiators. However, only the macroinitiators terminated with chlorine should be used. The corresponding macroinitiators with bromine as a transferable group did not yield well‐defined copolymers. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2688–2695, 2003 相似文献
18.
19.
Devon A. Shipp Xiang Yu 《Journal of polymer science. Part A, Polymer chemistry》2004,42(21):5548-5558
Kinetic studies of the atom transfer radical polymerization (ATRP) of styrene are reported, with the particular aim of determining radical‐radical termination rate coefficients (<kt>). The reactions are analyzed using the persistent radical effect (PRE) model. Using this model, average radical‐radical termination rate coefficients are evaluated. Under appropriate ATRP catalyst concentrations, <kt> values of approximately 2 × 108 L mol?1 s?1 at 110 °C in 50 vol % anisole were determined. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5548–5558, 2004 相似文献
20.
Gregory T. Lewis Van Nguyen Yoram Cohen 《Journal of polymer science. Part A, Polymer chemistry》2007,45(24):5748-5758
Controlled radical polymerization of 4‐vinylpyridine (4VP) was achieved in a 50 vol % 1‐methyl‐2‐pyrrolidone/water solvent mixture using a 2,2′‐azobis(2,4‐dimethylpentanitrile) initiator and a CuCl2/2,2′‐bipyridine catalyst–ligand complex, for an initial monomer concentration of [M]0 = 2.32–3.24 M and a temperature range of 70–80 °C. Radical polymerization control was achieved at catalyst to initiator molar ratios in the range of 1.3:1 to 1.6:1. First‐order kinetics of the rate of polymerization (with respect to the monomer), linear increase of the number–average degree of polymerization with monomer conversion, and a polydispersity index in the range of 1.29–1.35 were indicative of controlled radical polymerization. The highest number–average degree of polymerization of 247 (number–average molecular weight = 26,000 g/mol) was achieved at a temperature of 70 °C, [M]0 = 3.24 M and a catalyst to initiator molar ratio of 1.6:1. Over the temperature range studied (70–80 °C), the initiator efficiency increased from 50 to 64% whereas the apparent polymerization rate constant increased by about 60%. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5748–5758, 2007 相似文献