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1.
D. Bertin D. Gigmes S. Marque R. Maurin P. Tordo 《Journal of polymer science. Part A, Polymer chemistry》2004,42(14):3504-3515
During nitroxide‐mediated polymerization, the polymerization time decreases with an increasing rate constant of the cleavage of the NO? C bond of dormant alkoxyamines. Thus, knowledge of the factors influencing this cleavage is of considerable interest. We have prepared a series of SG1 2‐[N‐tert‐butyl‐N‐(1‐diethoxyphosphoryl‐2,2‐dimethylpropyl)aminoxyl] based alkoxyamines [SG1‐CH(Me)CO2R] with various R groups (alkyl or aryl) and measured the homolysis rate constants (kd). kd decreases with the bulkiness and increases with the polarity of the R group. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3504–3515, 2004 相似文献
2.
Gennady S. Ananchenko Marc Souaille Hanns Fischer Christophe Le Mercier Paul Tordo 《Journal of polymer science. Part A, Polymer chemistry》2002,40(19):3264-3283
Thermal reactions of the alkoxyamine diastereomers DEPN‐R′ [DEPN: N‐(2‐methylpropyl)‐N‐(1‐diethylphosphophono‐2,2‐dimethyl‐propyl)‐aminoxyl; R′: methoxy‐carbonylethyl and phenylethyl] with (R,R) + (S,S) and (R,S) + (S,R) configurations have been investigated by 1H NMR at 100 °C. During the overall decay the diastereomers interconvert, and an analytical treatment of the combined processes is presented. Rate constants are obtained for the cleavage and reformation of DEPN‐R′ from NMR, electron spin resonance, and chemically induced dynamic nuclear polarization experiments also using 2,2,6,6‐tetramethylpiperidinyl‐1‐oxyl (TEMPO) as a radical scavenger. The rate constants depend on the diastereomer configuration and the residues R′. Simulations of the kinetics observed with styrene and methyl methacrylate containing solutions yielded rate constants for unimeric and polymeric alkoxyamines DEPN‐(M)n‐R′. The results were compatible with the known DEPN mediation of living styrene and acrylate polymerizations. For methyl methacrylate the equilibrium constant of the reversible cleavage of the dormant chains DEPN‐(M)n‐R′ is very large and renders successful living polymerizations unlikely. Mechanistic and kinetic differences of DEPN‐ and TEMPO‐mediated polymerizations are discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3264–3283, 2002 相似文献
3.
Charlotte Dire Joël Belleney Julien Nicolas Denis Bertin Stéphanie Magnet Bernadette Charleux 《Journal of polymer science. Part A, Polymer chemistry》2008,46(18):6333-6345
Methyl methacrylate (MMA) was polymerized in bulk at 70 °C in the presence of an alkoxyamine initiator with low dissociation temperature (the so‐called BlocBuilder?) and increasing amounts of free N‐tert‐butyl‐N‐(1‐diethylphosphono‐2,2‐dimethylpropyl) nitroxide (SG1). Low final monomer conversions were reached, indicating a loss in radical activity due to side reactions such as irreversible homoterminations between the propagating radicals and β‐hydrogen transfer (also called disproportionation) from a propagating radical to a free‐SG1 nitroxide. Proton NMR and MALDI‐TOF mass spectrometry were used to analyze the polymer chain‐ends and to clearly identify the main mechanism of irreversible termination. In particular, it was shown that all polymer chains were terminated by an alkene function in the presence of a large excess of free SG1, meaning that β‐hydrogen transfer from PMMA propagating radicals to the nitroxide SG1 was the major chain‐stopping event. On the other hand, for a low excess of free SG1, the two termination modes coexisted. Kinetic modeling was then performed using the PREDICI software, and the rate constant of β‐hydrogen transfer, kβHtr, was estimated to be 1.69 × 103 L mol?1 s?1 at 70 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6333–6345, 2008 相似文献
4.
Gennady S. Ananchenko Hanns Fischer 《Journal of polymer science. Part A, Polymer chemistry》2001,39(20):3604-3621
The thermal decomposition of five alkoxyamines labeled TEMPO–R, where TEMPO was 2,2,6,6‐tetramethylpiperidinyl‐N‐oxyl and R was cumyl (Cum), 2‐tert‐butoxy‐carbonyl‐2‐propyl (PEst), phenylethyl (PhEt), 1‐tert‐butoxy‐carbonylethyl (EEst), or 1‐methoxycarbonyl‐3‐methyl‐3‐phenylbutyl (Acrylate‐Cum), was studied with 1H NMR in the absence and presence of styrene and methyl methacrylate. The major products were alkenes and the hydroxylamine 1‐hydroxy‐2,2,6,6‐tetramethyl‐ piperidine (TEMPOH), and in monomer‐containing solutions, unimeric and polymeric alkoxyamines and alkenes were also found. Furthermore, the reactions between TEMPO and the radicals EEst and PEst were studied with chemically induced dynamic nuclear polarization. In comparison with coupling, TEMPO reacted with the radicals Cum, PEst, PhEt, and EEst and their unimeric styrene adducts by disproportionation to alkenes and TEMPOH only to a minor extent (0.6–3%) but with the radical adducts to methyl methacrylate to a considerable degree (≥20%). Parallel to the radical cleavage, TEMPO–EEst (but not the other alkoxyamines or TEMPO–Acrylate‐Cum) underwent substantial nonradical decay. The consequences for TEMPO‐mediated living radical polymerizations are discussed. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3604–3621, 2001 相似文献
5.
Jae Min Bak Hyung‐il Lee 《Journal of polymer science. Part A, Polymer chemistry》2013,51(9):1976-1982
Novel thermoresponsive double‐hydrophilic fluorinated block copolymers were successfully synthesized by reversible addition‐fragmentation chain transfer (RAFT) polymerization. Poly[N‐(2,2‐difluoroethyl)acrylamide] (P2F) was synthesized via RAFT polymerization of N‐(2,2‐difluoroethyl)acrylamide (M2F) using 2‐dodecylsulfanylthiocarbonylsulfanyl‐2‐methylpropionic acid (DMP) as the chain transfer agent (CTA) and 2,2′‐azobisisobutyronitrile (AIBN) as the initiator. The resulting P2F macroCTA was further chain extended with N‐(2‐fluoroethyl)acrylamide (M1F) to yield poly{[N‐(2,2‐difluoroethyl)acrylamide]‐b‐[N‐(2‐fluoroethyl)acrylamide]} (P2F‐b‐P1F) block copolymers with different lengths of the P1F block. Molecular weight and molecular weight distribution were determined by gel permeation chromatography. The average molecular weight (Mn) of the resulting polymers ranged from 2.9 × 104 to 5.8 × 104 depending on the length of the P1F block. The molecular weight distribution was low (Mw/Mn = 1.11–1.19). Turbidimetry by UV‐Visble (UV‐Vis) spectroscopy, dynamic light scattering, and in situ temperature‐dependent 1H NMR measurements demonstrated that the P2F block underwent a thermal transition from hydrophilic to hydrophobic, which in turn induced self‐assembly from unimers to aggregates. Transmission electron microscopy studies demonstrated that polymeric aggregates formed from an aqueous solution of P2F‐b‐P1F at 60 °C were disrupted by cooling down to 20 °C and regenerated by heating to 60 °C. Temperature‐triggered release of a model hydrophobic drug, coumarin 102, was also demonstrated. © 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 相似文献
6.
Yanfei Hu Vincent Darcos Sophie Monge Suming Li 《Journal of polymer science. Part A, Polymer chemistry》2013,51(15):3274-3283
Novel thermo‐responsive poly(N‐isopropylacrylamide)‐block‐poly(l ‐lactide)‐block‐poly(N‐isopropylacylamide) (PNIPAAm‐b‐PLLA‐b‐PNIPAAm) triblock copolymers were successfully prepared by atom transfer radical polymerization of NIPAAm with Br‐PLLA‐Br macroinitiator, using a CuCl/tris(2‐dimethylaminoethyl) amine (Me6TREN) complex as catalyst at 25 °C in a N,N‐dimethylformamide/water mixture. The molecular weight of the copolymers ranges from 18,000 to 38,000 g mol?1, and the dispersity from 1.10 to 1.28. Micelles are formed by self‐assembly of copolymers in aqueous medium at room temperature, as evidenced by 1H NMR, dynamic light scattering (DLS) and transmission electron microscopy (TEM). The critical micelle concentration determined by fluorescence spectroscopy ranges from 0.0077 to 0.016 mg mL?1. 1H NMR analysis in selective solvents confirmed the core‐shell structure of micelles. The copolymers exhibit a lower critical solution temperature (LCST) between 32.1 and 32.8 °C. The micelles are spherical in shape with a mean diameter between 31.4 and 83.3 nm, as determined by TEM and DLS. When the temperature is raised above the LCST, micelle size increases at high copolymer concentrations due to aggregation. In contrast, at low copolymer concentrations, decrease of micelle size is observed due to collapse of PNIPAAm chains. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3274–3283 相似文献
7.
Gerson Lpez L. Marina Jaramillo Rodrigo Abonia Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(4):o168-o173
The molecules of N‐(3‐tert‐butyl‐1‐phenyl‐1H‐pyrazol‐5‐yl)‐2‐chloro‐N‐(4‐methoxybenzyl)acetamide, C23H26ClN3O2, are linked into a chain of edge‐fused centrosymmetric rings by a combination of one C—H...O hydrogen bond and one C—H...π(arene) hydrogen bond. In N‐(3‐tert‐butyl‐1‐phenyl‐1H‐pyrazol‐5‐yl)‐2‐chloro‐N‐(4‐chlorobenzyl)acetamide, C22H23Cl2N3O, a combination of one C—H...O hydrogen bond and two C—H...π(arene) hydrogen bonds, which utilize different aryl rings as the acceptors, link the molecules into sheets. The molecules of S‐[N‐(3‐tert‐butyl‐1‐phenyl‐1H‐pyrazol‐5‐yl)‐N‐(4‐methylbenzyl)carbamoyl]methyl O‐ethyl carbonodithioate, C26H31N3O2S2, are also linked into sheets, now by a combination of two C—H...O hydrogen bonds, both of which utilize the amide O atom as the acceptor, and two C—H...π(arene) hydrogen bonds, which utilize different aryl groups as the acceptors. 相似文献
8.
Activity and stability spontaneously enhanced toward ethylene polymerization by employing 2‐(1‐(2,4‐dibenzhydrylnaphthylimino)ethyl)‐6‐(1‐(arylimino)ethyl) pyridyliron(II) dichlorides
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Xinxin Wang Wenhong Yang Yan Chen Xiang Hao Xiaoping Cao Wen‐Hua Sun 《Journal of polymer science. Part A, Polymer chemistry》2017,55(6):988-996
A series of 2‐(1‐(2,4‐dibenzhydrylnaphthylimino)ethyl)‐6‐(1‐(arylimino)ethyl)pyridyliron(II) complexes ( Fe1 ? Fe5 ) was synthesized and characterized. The molecular structure of the representative Fe2 was determined by single‐crystal X‐ray diffraction, revealing a distorted pseudo‐square‐pyramidal geometry around the iron center. On activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all these iron complex precatalysts performed with high activities (up to 1.58 × 107 g (PE) mol?1 (Fe) h?1) toward ethylene polymerization, producing highly linear polyethylenes with high molecular weight and bimodal distribution, which was in accordance with high temperature 13C NMR, high T m values (T m ~130 °C) and the GPC curves of the obtained polyethylenes. Meanwhile, DFT calculation results also showed the good correlation between net charges on iron and experimental activities. Compared with previous bis(imino)pyridyliron analogues, the current iron complexes containing the benzhydrylnaphthyl groups exhibited relatively higher activities and better thermal‐stability at elevated temperatures, especially at 80 °C as the industrial operating temperature, and still showed high activities toward ethylene polymerization up to 8.57 × 106 g (PE) mol?1 (Fe) h?1 in the presence of co‐catalyst MMAO. In addition, these iron complex precatalysts all exhibited long lifetimes. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 988–996 相似文献
9.
The diorganotin(Ⅳ) complexes of N-(3,5-dibromosalicylidene)-α-amino acid, R2Sn(2-O-3,5-Br2C6H2CH= NCHRCOO)(where R=H, Me, i-Pr, Bz; R'=n-Bu, Cy), were synthesized by the reactions of diorganotin dichlorides with in situ formed potassium salt of N-(3,5-dibromosalicylidene)-α-amino acid and characterized by elemental analysis, IR and NMR (^1H, ^13C and ^119Sn) spectra. The crystal structures of n-Bu2Sn(2-O-3,5-Br2C6H2CH= NCHRCOO)(R=i-Pr, Bz) and Cy2Sn(2-O-3,5-Br2C6H2CH=NCHRCOO)(R=Me, Bz) were determined by X-ray single crystal diffraction and showed that the tin atoms are in a distorted trigonal bipyramidal geometry to form five- and six-membered chelate rings with the tridentate ligand. Bioassay results indicated that the compounds possess better in vitro antitumour activity against three human tumour cell lines, HeLa, CoLo205 and MCF-7, than cis-platin and moderate anti-bacterial activity against two bacteria, E. coli and S. aureus. 相似文献
10.
Zhaoliang Lin Zhaohua Huang Lianjun Shi Junlian Huang 《Journal of polymer science. Part A, Polymer chemistry》2000,38(14):2548-2554
The new monomer N′‐(β‐methacryloyloxyethyl)‐2‐pyrimidyl‐(p‐benzyloxy‐ carbonyl)aminobenzenesulfonamide (MPBAS) (M1) is synthesized using sulfadiazine as parent compound. It could be homopolymerized and copolymerized with N‐phenyl maleimide (NPMI) (M2) by radical mechanism using AIBN as initiator at 60 °C in dimethylformamide. The new monomer MPBAS and polymers were identified by IR, element analysis and 1H NMR in detail. The monomer reactivity ratios in copolymerization were determined by YBR method, and r1 (MPBAS) = 2.39 ± 0.05, r2 (NPMI) = 0.33 ± 0.02. In the presence of ammonium formate, benzyloxycarbonyl groups could be broken fluently from MPBAS segments of copolymer by catalytic transfer hydrogenation, and the copolymer with sulfadiazine side groups are recovered. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2548–2554, 2000 相似文献
11.
The thermal behavior and kinetic parameters of the exothermic decomposition reaction of N‐N‐bis[N‐(2,2,2‐tri‐nitroethyl)‐N‐nitro]ethylenediamine in a temperature‐programmed mode have been investigated by means of differential scanning calorimetry (DSC). The results show that kinetic model function in differential form, apparent activation energy Ea and pre‐exponential factor A of this reaction are 3(1 ‐α)2/3, 203.67 kJ·mol?1 and 1020.61s?1, respectively. The critical temperature of thermal explosion of the compound is 182.2 °C. The values of ΔS≠ ΔH≠ and ΔG≠ of this reaction are 143.3 J·mol?1·K?1, 199.5 kJ·mol?1 and 135.5 kJ·mol?1, respectively. 相似文献
12.
Kinetic study of the radical polymerization behavior of N‐(1‐phenylethylaminocarbonyl)methacrylamide
Makiko Seno Takahiro Yamada Hongwei Wang Tomohiro Hirano Tsuneyuki Sato 《Journal of polymer science. Part A, Polymer chemistry》2005,43(10):2013-2020
Polymerization of N‐(1‐phenylethylaminocarbonyl)methacrylamide (PEACMA) with dimethyl 2,2′‐azobisisobutyrate (MAIB) was kinetically studied in dimethyl sulfoxide (DMSO). The overall activation energy of the polymerization was estimated to be 84 kJ/mol. The initial polymerization rate (Rp) is given by Rp = k[MAIB]0.6[PEACMA]0.9 at 60 °C, being similar to that of the conventional radical polymerization. The polymerization system involved electron spin resonance (ESR) spectroscopically observable propagating poly(PEACMA) radical under the actual polymerization conditions. ESR‐determined rate constants of propagation and termination were 140 L/mol s and 3.4 × 104 L/mol s at 60 °C, respectively. The addition of LiCl accelerated the polymerization in N,N‐dimethylformamide but did not in DMSO. The copolymerization of PEACMA(M1) and styrene(M2) with MAIB in DMSO at 60 °C gave the following copolymerization parameters; r1 = 0.20, r2 = 0.51, Q1 = 0.59, and e1 = +0.70. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2013–2020, 2005 相似文献
13.
Makoto Eishima Shigeru Ohba Masumi Suzuki Chiaki Nagasawa Takeshi Sugai 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(11):1391-1393
In the racemic crystals of (1S,2R)‐ or (1R,2S)‐1‐[N‐(chloroacetyl)carbamoylamino]‐2,3‐dihydro‐1H‐inden‐2‐yl chloroacetate, C14H14Cl2N2O4, (I), the enantiomeric molecules form a dimeric structure via the N—H?O cyclic hydrogen bond of the carbamoyl moieties. In the chiral crystals of (—)‐(1S,2R)‐1‐[N‐(chloroacetyl)carbamoylamino]‐2,3‐dihydro‐1H‐inden‐2‐yl chloroacetate, C14H14Cl2N2O4, (II), the N—H?O intermolecular hydrogen bond forms a zigzag chain around the twofold screw axis. The melting points and calculated densities of (I) and (II) are 446 and 396 K, and 1.481 and 1.445 Mg m?3, respectively. 相似文献
14.
Bartosz Zarychta Anna Piecyk‐Mizgaa Zdzisaw Daszkiewicz Jacek Zaleski 《Acta Crystallographica. Section C, Structural Chemistry》2005,61(8):o515-o517
The structures of the two title isomeric compounds (systematic names: N‐methyl‐N,2‐dinitroaniline and N‐methyl‐N,3‐dinitroaniline, both C7H7N3O4) are slightly different because they exhibit different steric hindrances and hydrogen‐bonding environments. The aromatic rings are planar. The –N(Me)NO2 and –NO2 groups are not coplanar with the rings. Comparison of the geometric parameters of the ortho, meta and para isomers together with those of N‐methyl‐N‐phenylnitramine suggests that the position of the nitro group has a strong influence on the aromatic ring distortion. The crystal packing is stabilized by weak C—H⋯O hydrogen bonds to the nitramine group. 相似文献
15.
Christopher Glidewell John N. Low Janet M. S. Skakle Solange M. S. V. Wardell James L. Wardell 《Acta Crystallographica. Section C, Structural Chemistry》2002,58(8):o487-o490
In 2‐iodo‐N‐(3‐nitrobenzyl)aniline, C13H11IN2O2, the molecules are linked into a three‐dimensional structure by a combination of C—H?O hydrogen bonds, iodo–nitro interactions and aromatic π–π‐stacking interactions, but N—H?O and C—H?π(arene) hydrogen bonds are absent. In the isomeric 3‐iodo‐N‐(3‐nitrobenzyl)aniline, a two‐dimensional array is generated by a combination of N—H?O, C—H?O and C—H?π(arene) hydrogen bonds, but iodo–nitro interactions and aromatic π–π‐stacking interactions are both absent. 相似文献
16.
The synthesis, characterization and methyl methacrylate polymerization behaviors of 2‐(N‐arylimino)pyrrolide nickel complexes are described. The nickel complex [NN]2Ni ( 1 , [NN] = [2‐C(H)NAr‐5‐tBu‐C4H2N]?, Ar = 2,6‐iPr2C6H3) was prepared in good yield by the reaction of [NN]Li with trans‐[Ni(Cl)(Ph)(PPh3)2] in THF. Reaction of [NN]Li with NiBr2(DME) yielded the nickel bromide [NN]Ni(Br)[NNH] ( 2 ). Complexes 1 and 2 were characterized by 1H NMR and IR spectroscopy and elemental analysis, and by X‐ray single crystal analysis. Both complexes, upon activation with methylaluminoxane, are highly active for the polymerization of methyl methacrylate to give high molecular weight polymethylmethacrylate with narrow molecular distributions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
17.
Kejian Bian Michael F. Cunningham 《Journal of polymer science. Part A, Polymer chemistry》2006,44(1):414-426
Nitroxide‐mediated radical polymerization (NMRP) of 2‐(dimethylamino)ethyl acrylate (DMAEA) was carried out at 100–120 °C, initiated by MONAMS, an alkoxyamine based on N‐tert‐butyl‐N‐(1‐diethyl phosphono‐2,2‐dimethylpropyl)nitroxide, SG1. Controlled polymerization can be achieved by the addition of free SG1 (the initial molar ratio of SG1 to MONAMS ranged from 0.06 to 0.12), giving a linear first‐order kinetic plot up to 55–70% conversion depending on the reaction conditions. The molecular weights show a near linear increase with conversion; however, they deviate to some extent with theoretical values. SG1‐mediated polymerization of DMAEA at 112 °C is also controlled in organic solvents (N,N‐dimethylformide, anisole, xylene). Polymerization rate increases with increasing solvent polarity. Chain transfer to polymer produces ~1 mol % branches in bulk and 1.2–1.9 mol % in organic solvents, typical of those for acrylates. From poly(styrene) (pS) and poly(n‐butyl acrylate) (pBA) macroinitiators, amphiphilic di‐ and triblock copolymers p(S‐b‐DMAEA), p(DMAEA‐b‐S‐b‐DMAEA), p(BA‐b‐DMAEA), and p(DMAEA‐b‐BA‐b‐DMAEA) were synthesized via NMRP at 110 °C. Polymers were characterized by GPC, NMR, surface tension measurements, and DSC. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 414–426, 2006 相似文献
18.
Valérie Sciannamea Jean‐Marie Catala Robert Jérôme Christophe Detrembleur 《Journal of polymer science. Part A, Polymer chemistry》2007,45(7):1219-1235
Kinetics of the free radical polymerization of styrene at 110 °C has been investigated in the presence of C‐phenyl‐N‐tert‐butylnitrone (PBN) and 2,2′‐azobis(isobutyronitrile) (AIBN) after prereaction in toluene at 85 °C. The effect of the prereaction time and the PBN/AIBN molar ratio on the in situ formation of nitroxides and alkoxyamines (at 85 °C), and ultimately on the control of the styrene polymerization at 110 °C, has been investigated. As a rule, the styrene radical polymerization is controlled, and the mechanism is one of the classical nitroxide‐mediated polymerization. Only one type of nitroxide (low‐molecular‐mass nitroxide) is formed whatever the prereaction conditions at 85 °C, and the equilibrium constant (K) between active and dormant species is 8.7 × 10?10 mol L?1 at 110 °C. At this temperature, the dissociation rate constant (kd) is 3.7 × 10?3 s?1, the recombination rate constant (kc) is 4.3 × 106 L mol?1 s?1, whereas the activation energy (Ea,diss.), for the dissociation of the alkoxyamine at the chain‐end is ~125 kJ mol?1. Importantly, the propagation rate at 110 °C, which does not change significantly with the prereaction time and the PBN/AIBN molar ratio at 85 °C, is higher than that for the thermal polymerization at 110 °C. This propagation rate directly depends on the equilibrium constant K and on the alkoxyamine and nitroxide concentrations, as well. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1219–1235, 2007 相似文献
19.
Benoît Lessard Milan Marić 《Journal of polymer science. Part A, Polymer chemistry》2011,49(24):5270-5283
A series of poly(2‐(dimethylamino)ethyl methacrylate‐ran‐9‐(4‐vinylbenzyl)‐9H‐carbazole) (poly(DMAEMA‐ran‐VBK)) random copolymers, with VBK molar feed compositions fVBK,0 = 0.02–0.09, were synthesized using 10 mol % [tert‐butyl[1‐(diethoxyphosphoryl)‐2,2‐dimethylpropyl]amino] nitroxide (SG1) relative to 2‐([tert‐butyl[1‐(diethoxyphosphoryl)‐2,2‐dimethylpropyl]amino]oxy)‐2‐methylpropionic acid (BlocBuilder) at 80 °C and 90 °C. Controlled polymerizations were observed, even with fVBK,0 = 0.02, as reflected by a linear increase in number average molecular weight (Mn) versus conversion X ≤ 0.6 with final copolymers characterized by relatively narrow, monomodal molecular weight distributions (Mw/Mn ≈ 1.5). Poly(DMAEMA‐ran‐VBK) copolymers were deemed sufficiently pseudo‐“living” to reinitiate a second batch of N,N‐dimethylacrylamide (DMAA), with very few apparent dead chains, as indicated by the monomodal shift in the gel permeation chromatography chromatograms. Poly(DMAEMA‐ran‐VBK) random copolymers exhibited tuneable lower critical solution temperature (LCST), in aqueous solution, by modifying copolymer composition, solution pH and by the addition of the water‐soluble poly(DMAA) segment. 1H NMR analysis determined that, in water, the VBK units of the poly(DMAEMA‐ran‐VBK) random copolymer were segregated to the interior of the copolymer aggregate regardless of solution temperature and that poly(DMAEMA‐ran‐VBK)‐b‐poly(DMAA) block copolymers formed micelles above the LCST. In addition, the final random copolymer and block copolymer exhibited temperature dependent fluorescence due to the VBK units. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
20.
The title compound, N‐(2‐pyridylmethyl)salicylamide ( 1 ), was synthesized by ester aminolysis of methyl salicylate and 2‐picolylamine. In the presence of triethylamine as a supporting base, the salicylamide moiety reacts with the organodichlorosilanes RR′SiCl2 to form the desired six‐membered heterocycles of the type RR′Si–O–(o‐C6H4)–C(=O)N(pic), with pic being the 2‐pyridylmethyl (i.e., 2‐picolyl) moiety and RR′ = Me, Me ( 2a ); Me, Ph ( 2b ); Ph, Ph ( 2c ); Bn, Bn ( 2d ); All, Ph ( 2e ) and Ph, H ( 2f ). Despite the absence of notable ring strain release Lewis acidity (i.e., only a six‐membered chelate is formed by the dianion, and smaller rings are not present in the compound), the poor electron withdrawal from silicon by its C– or H– substituents and the flexible methylene bridge between the salicylamide and the pyridine moiety, the pyridine N donor atom furnishes pentacoordinate silicon coordination spheres in all of these compounds 2a – 2f . The coordination number of the silicon atom was confirmed by single‐crystal X‐ray diffraction analysis for the solid state and by 29Si NMR spectroscopy for the solution state. 相似文献