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1.
The polymerization of MMA, at ambient temperature, mediated by dansyl chloride is investigated using controlled radical polymerization methods. The solution ATRP results in reasonably controlled polymerization with PDI < 1.3. The SET‐LRP polymerization is less controlled while SET‐RAFT polymerization is controlled producing poly(methyl methacrylate) (PMMA) with the PDI < 1.3. In all the cases, the polymerization rate followed first order kinetics with respect to monomer conversion and the molecular weight of the polymer increased linearly with conversion. The R group in the CTAs do not appear to play a key role in controlling the propagation rate. SET‐RAFT method appears to be a simpler tool to produce methacrylate polymers, under ambient conditions, in comparison with ATRP and SET‐LRP. Fluorescent diblock copolymers, P(MMA‐b‐PhMA), were synthesized. These were highly fluorescent with two distinguishable emission signatures from the dansyl group and the phenanthren‐1‐yl methacrylate block. The fluorescence emission spectra reveal interesting features such as large red shift when compared to the small molecule. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

2.
Polystyrene (PSt) radicals and poly(methyl acrylate) (PMA) radicals, derived from their monobrominated precursors prepared by atom transfer radical polymerization (ATRP), were formed in the presence of the radical trap 2‐methyl‐2‐nitrosopropane (MNP), selectively forming PSt‐PMA diblock copolymers with an alkoxyamine at the junction between the block segments. This radical trap‐assisted, atom transfer radical coupling (RTA‐ATRC) was performed in a single pot at low temperature (35 °C), while analogous traditional ATRC reactions at this temperature, which lacked the radical trap, resulted in no observed coupling and the PStBr and PMABr precursors were simply recovered. Selective formation of the diblock under RTA‐ATRC conditions is consistent with the PStBr and PMABr having substantially different KATRP values, with PSt radicals initially being formed and trapped by the MNP and the PMA radicals being trapped by the in situ‐formed nitroxide end‐capped PSt. The midchain alkoxyamine functionality was confirmed by thermolysis of the diblock copolymer, resulting in recovery of the PSt segment and degradation of the PMA block at the relatively high temperatures (125 °C) required for thermal cleavage. A PSt‐PMA diblock formed by chain extenstion ATRP using PStBr as the macroinitiator (thus lacking the alkoxyamine between the PSt‐PMA segements) was inert to thermolysis. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3619–3626  相似文献   

3.
A detailed exploration of the atom transfer radical polymerization (ATRP) of a sugar‐carrying monomer, 6‐O‐methacryloyl‐1,2;3,4‐di‐O‐isopropylidene‐D‐galactopyranose (MAIPGal) was performed. The factors pertinent to ATRP, such as initiators, ligands, catalysts, and temperature were optimized to obtain good control over the polymerization. The kinetics were examined in detail when the polymerization was initiated by methyl 2‐bromoisopropionate (2‐MBP), ethyl 2‐bromoisobutyrate (2‐EBiB), or a macroinitiator, [α‐(2‐bromoisobutyrylate)‐ω‐methyl PEO] (PEO–Br), with bipyridine (bipy) as the ligand at 60 °C or by 2‐EiBB with N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) as the ligand at room temperature (23 °C). The effects of the catalysts (CuBr and CuCl) were also investigated. We demonstrate that the successful ATRP of MAIPGal can be achieved for 2‐EBiB/CuBr/bipy and 2‐MBP/CuCl/bipy at 60 °C and for 2‐EBiB/CuBr/PMDETA at room temperature. The initiation by 2‐EBiB at room temperature with PMDETA as the ligand should be the most optimum operation for its moderate condition and suppression of many side reactions. Chain extension of P(MAIPGal) prepared by ATRP with methyl methacrylate (MMA) as the second monomer was carried out and a diblock copolymer, P(MAIPGal)‐b‐PMMA, was obtained. Functional polymers, poly(D‐galactose 6‐methacrylate) (PGMA), PEO‐b‐PGMA, and PGMA‐b‐PMMA were obtained after removal of the protecting groups. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 752–762, 2005  相似文献   

4.
Tetrakis(4‐(1‐bromoethyl)phenyl)silane is synthesized and utilized to initiate the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) to generate bromo‐terminated four‐armed PMMA macroinitiators, which further initiate the ATRP of methylacryloyloxyl‐2‐hydroxypropyl perfluorooctanoate (FGOA) to create fluorinated star‐shaped block copolymers PMMA‐b‐poly(FGOA)s with fluorine content ranging from 0 to 31.7 wt %. The polymerizations are well controlled with the polydispersity indices <1.30. The polymers readily dissolve in common organic solvents and show good film‐formation. Compared with the nonfluorinated sample, the fluorinated films exhibit significantly increased water contact angles owing to the enrichment of fluorine on the surface. The enhanced hydrophobicity is advantageous for the optical stability when the devices work under a moist environment. Moreover, the films possess high thermo‐optic coefficients, tunable refractive indices, and extremely low birefringence coefficients because of the presence of bulky and rigid tetraphenylsilane core and star‐shaped topological structure, showing potential application in optical waveguide devices. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1969–1977  相似文献   

5.
This study reports an application of trichloroethanol (TCE) as a bifunctional initiator for the synthesis of block copolymers (BCPs) by organocatalyzed ring‐opening polymerization (OROP) and atom transfer radical polymerization (ATRP). TCE was employed to synthesize a low dispersity poly (valerolactone) macroinitiator, which was subsequently used for the ATRP of tert‐butyl methacrylate. While it is known that TCE can serve as an initiator in ATRP, the ability to induce polymerization under OROP is reported for the first time. The formation of well‐defined BCPs was confirmed by gel permeation chromatography and 1H NMR. Computational studies were performed to obtain a molecular‐level understanding of the ring‐opening polymerization mechanism involving TCE as initiator. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 563–569  相似文献   

6.
In this contribution, we reported the synthesis of a hyperbranched block copolymer composed of poly(ε‐caprolactone) (PCL) and polystyrene (PS) subchains. Toward this end, we first synthesized an α‐alkynyl‐ and ω,ω′‐diazido‐terminated PCL‐b‐(PS)2 macromonomer via the combination of ring‐opening polymerization and atom transfer radical polymerization. By the use of this AB2 macromonomer, the hyperbranched block copolymer (h‐[PCL‐b‐(PS)2]) was synthesized via a copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition (i.e., click reaction) polymerization. The hyperbranched block copolymer was characterized by means of 1H nuclear magnetic resonance spectroscopy and gel permeation chromatography. Both differential scanning calorimetry and atomic force microscopy showed that the hyperbranched block copolymer was microphase‐separated in bulk. While this hyperbranched block copolymer was incorporated into epoxy, the nanostructured thermosets were successfully obtained; the formation of the nanophases in epoxy followed reaction‐induced microphase separation mechanism as evidenced by atomic force microscopy, small angle X‐ray scattering, and dynamic mechanical thermal analysis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 368–380  相似文献   

7.
A combination of living polymerization of ylides and atom transfer radical polymerization (ATRP) was used successfully in the design and synthesis of well‐defined polymethylene‐b‐poly(methyl methacrylate) (PM‐b‐PMMA) and polymethylene‐b‐poly(n‐butyl acrylate) (PM‐b‐Pn‐BuA). Tripolymethylene borane were firstly synthesized by living polymerization of dimethylsulfoxonium methylides and then oxidated quantitatively through trimethylamine‐N‐oxide dihydrate to provide a series of low‐polydispersity hydroxyl‐terminated polymethylenes (PM‐OHs) with different molecular weight. Subsequently, such polymers were converted into polymethylene‐based macroinitiators (PM‐MIs, Mn(GPC) = 1900–10,400 g/mol; Mw/Mn = 1.12–1.23) in ~100% conversion. ATRPs of methyl methacrylate and n‐butyl acrylate were successfully conducted using PM‐MI to produce well‐defined diblock copolymers of PM‐b‐PMMA and PM‐b‐Pn‐BuA, respectively. The GPC traces indicated the successful extension of PMMA and Pn‐BuA segment (Mn(GPC) of PM‐b‐PMMA = 3980–10,100 g/mol; Mw/Mn = 1.16–1.22; Mn of PM‐b‐Pn‐BuA = 7400–9200 g/mol; Mw/Mn = 1.14–1.18). Atomic force microscopy (AFM) was used to characterize the structures of the precipitated PM‐b‐PMMA micelles, which were formed in toluene. The blend of LDPE/PMMA was prepared with PM‐b‐PMMA as compatibilizer. The scanning electron microscopy (SEM) results showed that the compatibilization of the LDPE/PMMA was improved greatly by the incorporation of PM‐b‐PMMA. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5671–5681, 2009  相似文献   

8.
9.
The linear poly(ε–caprolacton)‐b‐hyperbrached poly(2‐((α‐bromobutyryl)oxy)ethyl acrylate) (LPCL‐b‐HPBBEA) has been successfully synthesized by simultaneous ring‐opening polymerization (ROP) of CL and self‐condensing vinyl polymerization (SCVP) of BBEA in one‐pot. The HPBBEA homopolymers were found to be formed in the polymerization because of the competitive reactions induced by initiation with bifunctional initiator, 2‐hydroxylethyl‐2′‐bromoisobutyrate (HEBiB), and inimer BBEA. The separation of LPCL‐b‐HPBBEA from the polymerization products was achieved by precipitation in methanol. With feed ratio increase of CL and BBEA to HEBiB, the molecular weights of PCL and HPBBEA blocks in the block copolymer enhanced; and the polymerization rate of CL started to decrease gradually after 12 h of polymerization, but the polymerization rate of BBEA was maintained until 24 h of polymerization. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7628–7636, 2008  相似文献   

10.
Atom transfer radical polymerization was used to prepare well‐defined vinyl polyoxadiazole homomacromonomers with a properly modified α‐dicarboxylic acid methyl ester as the initiator. Macromonomers of various molecular weights with narrow polydispersities in some cases were obtained, as proved by gel permeation chromatography (GPC). The structures of the obtained macromonomers were then identified with 1H NMR spectroscopy. These macromonomers were subsequently copolymerized with a dihydroxy anthracene based monomer by a polycondensation technique, and this resulted in polymacromonomers. Coil–rod–coil copolymers containing side‐chain anthracene and oxadiazole units were also synthesized by atom transfer radical polymerization. The resulting copolymers combined an anthracene derivative as the rigid block with a random copolymer of the desired anthracene‐ and/or oxadiazole‐based monomers as the flexible block. These copolymers were primarily characterized with GPC and 1H NMR techniques. Additionally, the optical properties of all these copolymers were investigated in detail, and they suggested energy transfer from the oxadiazole to the anthracene chromophores, which became much more efficient in the solid state. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1049–1061, 2005  相似文献   

11.
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   

12.
三嵌段共聚物PAN-b-PEG-b-PAN的合成及其自组装行为的研究   总被引:3,自引:0,他引:3  
雷忠利  刘亚兰 《化学学报》2006,64(24):2403-2408
利用原子转移自由基聚合(ATRP)制得了分子量可控、分子量分布窄的聚丙烯腈-b-聚乙二醇-b-聚丙烯腈P(AN-b-PEG-b-PAN)嵌段共聚物. 通过1H NMR, FTIR, 凝胶渗透色谱(GPC)对所得产物的结构和分子量进行了表征并通过TG和DTA考察了该嵌段共聚物的热稳定性; 运用透射电子显微镜(TEM)、荧光探针技术和动态光散射(DLS)研究了P(AN)27-b-P(EG)45-b-P(AN)27在溶剂水中胶束的形成、结构、形貌和胶束粒径. 结果表明, 三嵌段共聚物P(AN)27-b-P(EG)45-b-P(AN)27的热稳定性较纯聚乙二醇P(EG)好, 且柔性链PEG的引入对嵌段共聚物的放热峰位置没有显著的影响. 当改变此嵌段共聚物溶液浓度时, 该嵌段共聚物会自组装成不同形状的胶束, DLS测量的胶束粒径大于TEM观察的结果, 其临界胶束浓度(cmc)约为4.46×10-4 g•L-1.  相似文献   

13.
Atom transfer radical polymerizations (ATRPs) of 1‐(4‐methacryloyloxy‐benzyl)thymine (MAT) and 9‐(2‐methacryloyloxyethyl)adenine (MAA) were conducted for the synthesis of DNA‐base functionalized polymers. The association equilibrium constant Kasso between MAT and MAA and the complexation equilibrium constant Kcomp between the corresponding polymers PMAT and PMAA were determined. A zipper‐like diblock copolymer, PMAT‐b‐PMAA, was prepared by anchoring the PMAT and PMAA blocks on the ortho‐positions of a pyridine ring via a successive two‐step ATRP. Dynamic light scattering and atom force microscopy confirmed that the block copolymer had a V‐shaped configuration in dimethylsulfoxide/N,N‐dimethylformamide. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5995–6006, 2006  相似文献   

14.
Amphiphilic diblock copolymer polycaprolactone‐block‐poly(glycidyl methacrylate) (PCL‐b‐PGMA) was synthesized via enzymatic ring‐opening polymerization (eROP) and atom transfer radical polymerization (ATRP). Methanol first initiated eROP of ?‐caprolactone (?‐CL) in the presence of biocatalyst Novozyme‐435 under anhydrous conditions. The resulting monohydroxyl‐terminated polycaprolactone (PCL–OH) was subsequently converted to a bromine‐ended macroinitiator (PCL–Br) for ATRP by esterification with α‐bromopropionyl bromide. PCL‐b‐PGMA diblock copolymers were synthesized in a subsequent ATRP of glycidyl methacrylate (GMA). A kinetic analysis of ATRP indicated a living/controlled radical process. The macromolecular structures were characterized for PCL–OH, PCL–Br, and the block copolymers by means of nuclear magnetic resonance, gel permeation chromatography, and infrared spectroscopy. Differential scanning calorimetry and wide‐angle X‐ray diffraction analyses indicated that the copolymer composition (?‐CL/GMA) had a great influence on the thermal properties. The well‐defined, amphiphilic diblock copolymer PCL‐b‐PGMA self‐assembled into nanoscale micelles in aqueous solutions, as investigated by dynamic light scattering and transmission electron microscopy. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5037–5049, 2007  相似文献   

15.
The synthesis of poly(methyl acrylate)-block-poly(gamma-benzyl-L-glutamate) (PMA-b-PBLG) diblock copolymers, using atom-transfer radical polymerization (ATRP) of methyl acrylate and living polymerization of gamma-benzyl-L-glutamate-N-carboxyanhydride (Glu-NCA) is described. Amido-amidate nickelacycle end groups were incorporated onto amino-terminated poly(methyl acrylates), and the resulting complexes were successfully used as macroinitiators for the growth of polypeptide segments. This method allows the controlled preparation of polypeptide-block-poly(methyl acrylate) diblock architectures with control over polypeptide chain length and without the formation of homopolypeptide contaminants.  相似文献   

16.
The polymers poly[(2,2‐dimethyl‐1,3‐dioxolane‐4yl) methyl acrylate] (PDMDMA) and four‐armed PDMDMA with well‐defined structures were prepared by the polymerization of (2,2‐dimethyl‐1,3‐dioxolane‐4yl) methyl acrylate (DMDMA) in the presence of an atom transfer radical polymerization (ATRP) initiator system. The successive hydrolyses of the polymers obtained produced the corresponding water‐soluble polymers poly(2,3‐dihydroxypropyl acrylate) (PDHPA) and four‐armed PDHPA. The controllable features for the ATRP of DMDMA were studied with kinetic measurements, gel permeation chromatography (GPC), and NMR data. With the macroinitiators PDMDMA–Br and four‐armed PDMDMA–Br in combination with CuBr and 2,2′‐bipyridine, the block polymerizations of methyl acrylate (MA) with PDMDMA were carried out to afford the AB diblock copolymer PDMDMA‐b‐MA and the four‐armed block copolymer S{poly[(2,2‐dimethyl‐1,3‐dioxolane‐4yl) methyl acrylate]‐block‐poly(methyl acrylate)}4, respectively. The block copolymers were hydrolyzed in an acidic aqueous solution, and the amphiphilic diblock and four‐armed block copolymers poly(2,3‐dihydroxypropyl acrylate)‐block‐poly(methyl acrylate) were prepared successfully. The structures of these block copolymers were verified with NMR and GPC measurements. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3062–3072, 2001  相似文献   

17.
Monomers bearing an activated ester group can be polymerized under various controlled polymerization techniques, such as ATRP, NMP, RAFT polymerization, or ROMP. Combining the functionalization of polymers via polymeric activated esters with these controlled polymerization techniques generate possibilities to realize highly functionalized polymer architectures. Within this highlight two different research areas of activated esters in polymer science will be discussed: (i) the preparation of defined reactive polymer architectures by controlled polymerization techniques and (ii) the preparation of defined reactive thin films. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6677–6687, 2008  相似文献   

18.
A poly(methyl methacrylate)‐block‐poly(4‐vinylpyridine)‐block‐polystyrene (PMMA‐b‐P4VP‐b‐PS) triblock terpolymer is synthesized by ATRP to study its self‐assembly with PAA in organic solvents. The self‐assembly behavior of this system is compared with the one of a mixture of two diblocks, namely polystyrene‐block‐poly(4‐vinylpyridine) (PS‐b‐P4VP) and poly(methyl methacrylate)‐block‐poly(methacrylic acid) (PMMA‐b‐PMAA). For both systems, formation of hydrogen‐bonded complexes between the P4VP and PMAA or PAA blocks occurs. These complexes become insoluble in the solvent used and micelles with a P4VP/P(M)AA complexes core surrounded by PS and PMMA coronal chains are obtained in both cases. These micelles are analyzed by DLS and TEM. Spherical micelles are formed for both systems but the hydrodynamic radii obtained for the two types of micelles are different. Indeed, the micelles formed by the PMMA‐b‐P4VP‐b‐PS + PAA system are smaller than those observed for the PS‐b‐P4VP + PMMA‐b‐PMAA system. Finally, the effect of the molar ratio of the P4VP/PMAA complexing blocks is investigated. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 459–467  相似文献   

19.
A novel method for preparation the comb‐like copolymers with amphihilic poly(ethylene oxide)‐block‐poly(styrene) (PEO‐b‐PS) graft chains by “graft from” and “graft onto” strategies were reported. The ring‐opening copolymerization of ethylene oxide (EO) and ethoxyethyl glycidyl ether (EEGE) was carried out first using α‐methoxyl‐ω‐hydroxyl‐poly(ethylene oxide) (mPEO) and diphenylmethyl potassium (DPMK) as coinitiation system, then the EEGE units on resulting linear copolymer mPEO‐b‐Poly(EO‐co‐EEGE) were hydrolyzed and the recovered hydroxyl groups were reacted with 2‐bromoisobutyryl bromide. The obtained macroinitiator mPEO‐b‐Poly(EO‐co‐BiBGE) can initiate the polymerization of styrene by ATRP via the “Graft from” strategy, and the comb‐like copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] were obtained. Afterwards, the TEMPO‐PEO was prepared by ring‐opening polymerization (ROP) of EO initiated by 4‐hydroxyl‐2,2,6,6‐tetramethyl piperdinyl‐oxy (HTEMPO) and DPMK, and then coupled with mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐PS] by atom transfer nitroxide radical coupling reaction in the presence of cuprous bromide (CuBr)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine (PMDETA) via “Graft onto” method. The comb‐like block copolymers mPEO‐b‐[Poly(EO‐co‐Gly)‐g‐(PS‐b‐PEO)] were obtained with high efficiency (≥90%). The final product and intermediates were characterized in detail. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1930–1938, 2009  相似文献   

20.
Surface‐pattern formation in thin block copolymer films was investigated by utilizing a high‐throughput methodology to validate the combinatorial measurement approach and to demonstrate the value of the combinatorial method for scientific investigation. We constructed measurement libraries from images of subregions of block copolymer films having gradients in film thickness and a range of molecular mass, M. A single gradient film covers a wide range of film morphologies and contains information equivalent to a large number of measurements of films having a fixed thickness, h. Notably, the scale of the surface patterns is generally much larger than the molecular dimensions so that the interpretation of the patterns is more subtle than ordering in bulk block copolymer materials, and there is no predictive theory of this type of surface‐pattern formation. We observed a succession of surface patterns that repeat across the film with increasing h [extended smooth regions, regions containing circular islands, labyrinthine (“spinodal”) patterns, holes, and smooth regions again]. The extended smooth regions and the labyrinthine patterns appear to be novel features revealed by our combinatorial study, and these patterns occurred as bands of h that were quantized by integral multiples of the bulk lamellar period, Lo. The magnitude of the height gradient influenced the width of the bands, and the smooth regions occupied an increasing fraction of the film‐surface area with an increasing film gradient. The average size of the spinodal patterns, λ, was found to scale as λ ~ L or λ ~ M?1.65 and reached a limiting size at long annealing times. The hole and island features had a size comparable to λ, and their size likewise decreased with increasing M. The smooth regions were attributed to an increase in the surface‐chain density in the outer brushlike block copolymer layer with increasing h, and the scaling of λ with M was interpreted in terms of the increasing surface elasticity with M. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 2141–2158, 2001  相似文献   

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