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1.
The cationic polymerization of cyclopentadiene (CPD) with 1-(4-methoxyphenyl)ethanol (1)/BF3OEt2 initiating system in CH2Cl2:CH3CN 4:1 (v/v) mixture at room temperature and in the presence of water ([H2O]/[BF3OEt2] up to 8) is reported. The number-average molecular weights of obtained polymers increased in direct proportion to monomer
conversion or initial monomer concentration (M
n ≤ 4,000 g mol−1) in agreement with calculated values, and were inversely proportional to initiator concentration. Polymer MWDs were relatively
narrow (M
w/M
n = 1.4–1.7) up to 60% of monomer conversion. It was also shown that regioselectivity of CPD polymerization with 1/BF3OEt2 initiating system did not depend significantly on water, monomer, or initiator concentration (1,4-structures content was
nearly 60% in all cases). 相似文献
2.
Novel triazole-based aluminum complex {O,O′-[4,5-P(O)Ph2tz]-AlMe2 was studied as the catalyst for the ring-opening polymerization of caprolactone (ε-CL) in chlorobenzene. In the presence
of methanol, isopropanol, and bifunctional poly(ethylene glycol), the catalytic system produced polymers with high conversion
(81–85 %) but broader distribution (M
w/M
n = 1.5–1.8). The system of catalyst and benzyl alcohol produced relative monodisperse PCLs (M
w/M
n ~ 1.2) with defined molecular weight at 1/1ratio, 60 °C and an initial concentration of ε-CL equal to 0.5 mol/L. 相似文献
3.
Dawn M. Jennings Sarah E. Brady Ginger V. Shultz Lev N. Zakharov David R. Tyler 《Polymer Bulletin》2012,68(9):2243-2254
The (CH3)2Si[CpMo(CO)3]2 complex (1) was synthesized and used to explore ring-opening polymerization (ROP) as a method to prepare high molecular weight polymers
containing Mo–Mo bonds along their backbones. Attempts to initiate ROP of 1 using n-BuLi or PtCl2 did not yield any polymers. The X-ray crystal structure of 1 shows that the Si center is not strained, and it is suggested that no ROP occurred because 1 is less strained than other organometallic ROP monomers, such as the silicon-bridged ferrocenophanes. Thermal ROP (TROP)
of 1 was successful and yielded a polymer (M
w = 210,000 g mol−1) containing both Mo–Mo single bonds and Mo≡Mo triple bonds. When CO(g) is passed over the polymer in the solid state, the Mo≡Mo triple bonds are converted to Mo–Mo single bonds. Attempts to increase
the yield of the TROP polymer by increasing the reaction times led to polymer decomposition. The decomposition is likely caused
by the weakness of the Mo–Mo bond, cleavage of which causes the polymer to degrade. 相似文献
4.
Activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) is a new technique for conducting
ATRP developed recently. In this work, an iron(III)-mediated AGET ATRP of styrene in bulk was carried out at 110 °C, using
benzyl bromide as an initiator, oxidatively stable iron(III) chloride hexahydrate (FeCl3·6H2O) as a catalyst, triphenyl phosphine as a ligand, and ascorbic acid as a reducing agent. The polymerizations demonstrated
the features of “living”/controlled free-radical polymerization, such as the number–average molecular weights increasing linearly
with monomer conversion and narrow molecular weight distributions (M
w/M
n = 1.14–1.31). 相似文献
5.
Summary N-Hydroxypyridine-2-thione derivativesIa-c and N-hydroxy-4-methylthiazole-2(3H)-thione derivativesIIa-b act as chain transfer agents in free radical polymerizations of methyl methacrylate (C
x
=0.6–4.3), styrene (C
x
=0.32–3.9), methyl acrylate (C
x
=3.1–20), and vinyl acetate (C
x
=9.7–80) at 60°C. Some retardation occurs with vinyl acetate and methyl acrylate.Ib also has the property of initiating the polymerization of methyl methacrylate photochemically, whileIIb acts as a thermal initiator. The chain transfer constants ofIIb make it particularly suitable for regulating molecular weight in batch polymerizations of methyl methacrylate and styrene. 相似文献
6.
Jieai Li Zhengbiao Zhang Xiulin Zhu Jian Zhu Zhenping Cheng Wenjian Xu 《Polymer Bulletin》2010,64(1):1-13
The stable free radical polymerizations of styrene were investigated with five 4-sulphonate-2,2,6,6-tetramethylpiperidine-N-oxyl stable radicals as mediators and benzoyl peroxide (BPO) as initiators at 125 °C. The results indicated that the polymerizations
proceeded in a “living”/controlled manner, i.e., the polymerization rates were first-order with respect to the monomer concentrations,
molecular weights increased linearly with conversions and the molecular weight distributions were relatively low (M
w/M
n = 1.2–1.4), 1H NMR analysis of the polymer chain-ends and successful chain extensions. The polymerization rates were faster than that of
4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl (OH-TEMPO) mediated ones. The effects of steric interference of different substitute groups at four-position of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), the molar ratios of stable radical to BPO and the temperature on the polymerizations were investigated. 相似文献
7.
Minggang Hu Mei Wang Peili Zhang Kun Jin Yuee Chen Licheng Sun 《Polymer Bulletin》2012,68(7):1789-1799
The hydroxyl- and phenoxy-bridged dinuclear zirconium and hafnium complexes, 1 and 2, containing a chiral N atom in the N2O2 ligand (H2L = 2-(((2-pyridylmethyl)(2-hydroxyphenyl)amino)methyl)-4,6-di(tert-butyl)phenol) were used as catalysts for the ring-opening polymerization of rac-lactide. Experiments prove that 1 and 2 are living and controlled catalytic systems with activity up to 3.25 gpol mmolini
−1 h−1. The isotactic-rich polylactides in a narrow polydispersity (M
w/M
n = 1.01–1.13) were produced with enantiomeric complexes 1 and 2 (P
m = 0.65–0.73). The kinetic studies show a first-order dependency in both monomer and initiator. The initiation mechanism is
discussed on the basis of the MALDI-TOF MS and 1H NMR spectra of the rac-LA oligomer prepared by 1. 相似文献
8.
The star-shaped polymethyl acrylate (PMA) was synthesized by single electron transfer living radical polymerization (SET-LRP)
at 30 °C in dimethyl sulfoxide, using 2,2-dibromomethyl-1,3-dibromopropane as the multifunctional initiator, Cu0 powder and tris-(2-dimethylamino ethyl)amine (Me6-TREN) as catalyst. The structure of polymer was analyzed by 1H NMR, and the results showed that the star-shaped PMA had perfect chain ends (–Br) retention. In addition, the polymerization
proceeded smoothly and the time dependence of ln([M]0/[M]) was linear, which could indicate a first order propagation rate with respect to both radicals and monomer concentration,
the polymerization was the living polymerization. The M
n and M
w/M
n of polymer were being measured by Gel Permeation Chromatography. The k
papp = 0.0367 h−1 and the conversion was 36.3% at 16 h, meanwhile the M
nGPC of the polymer was 13,300 and the M
w/M
n was 1.40. 相似文献
9.
Katsuyuki Tsuda Ken'ichi Tsutsumi Manabu Yaegashi Masahiro Miyajima Takashi Ishizone Akira Hirao Fumiaki Ishii Toyoji Kakuchi 《Polymer Bulletin》1998,40(6):651-658
Summary
The radical polymerizations of 2-, 3-, and 4-(phenylethynyl)styrenes (1a–c) and the copolymerizations of 1a–c (M1) with styrene (M2) were carried out using AIBN as the initiator in toluene at 60°C. The number-average molecular weights (M
ns) were extremely low for poly(2-phenylethynylstyrene) (2a) and poly[(phenylethynyl)styrene-co-styrene] (3a), and increased in the order of 2a, 3a << 2b, 3b < 2c, 3c. Monomer reactivity ratios were determined as r
1= 1.80 and r
2= 0.51 for 1a, r
1= 1.72 and r
2= 0.53 for 1b, and r
1= 3.17 and r
2= 0.24 for 1c. Polymers 2a–c and 3a–c underwent an exothermic reaction at elevated temperature to form organic solvent-insoluble polymers. Although the decomposition
of 2a was observed from 200°C, 2b and 2c exhibited a high heat-resistance property in both nitrogen and air atmospheres, in particular, 2b showed no significant weight loss below 450°C.
Received: 28 January 1998/Accepted: 5 March 1998 相似文献
10.
Feng Guo Baoyong Zhu Xiuling Zhang 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(1):118-123
Two new metal coordination polymers [Zn(dpa)(bim)]
n
and [Ni(dpa)(bpp)]
n
, (H2dpa = 3,4′-Biphenyl-dicarboxylic acid, bim = Benzimidazole and bpp = 1,3-Di (4-pyridyl)-propane) have been synthesized and
structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray analyses reveal that the
3,4′-diphenic acids act as bridging ligands, exhibiting three coordination modes to link metal ions: μ
2–η
1: η
1, μ
1–η
1: η
0 and μ
1
–η1: η1. Compound 1 demonstrates a one-dimensional zigzag chain. There exists intermolecular hydrogen bonding interactions in compound 1 which lead to form supramolecular structure. Compound 2 is a two-dimensional (4,4) net, and further assembled twofold interpenetrating net. Furthermore, compound [Zn(dpa)(bim)]
n
shows intense photoluminescence at room temperature. 相似文献
11.
Yozo Miura Shiro Mibae Hiroaki Moto Norihiro Nakamura Bunichiro Yamada 《Polymer Bulletin》1999,42(1):17-24
Summary
The bulk polymerization of styrene at 110 °C in the presence of 7-oxo-15-azadispiro[5.2.5.1]pentadecanyl-N-oxyl was investigated. The M
n values of poly(St) formed were increased linearly with conversion, and the M
w/M
n values were 1.48–1.54 at 90% conversion. On the basis of the results it was concluded that 1 controlled radical polymerization of St.
Received: 19 October 1998/Revised version: 21 November 1998/Accepted: 26 November 1998 相似文献
12.
Xiuling Zhang Baoyong Zhu Yulan Song Feng Guo Yongliang Liu 《Journal of Inorganic and Organometallic Polymers and Materials》2011,21(3):711-717
Three new coordination polymers [Cd(L)(4,4′-bipy)0.5]n (1), {[Mn(L)(bpp)]·H2O}n (2) and [Ni(L)(2,2′-bipy)(H2O)2]n(3) [H2L = Benzopenone-2,4′-dicarboxylic acid, 4,4′-bipy = 4,4′-bipy ridine, bpp = 1,3-di(4-pyridyl) propane and 2,2′-bipy = 2,2′-bipyridine]
have been synthesized and structurally characterized by elemental analysis, IR and X-ray diffraction. Single-crystal X-ray
analyses revealed that the H2L ligand acts as a bridge, exhibiting three coordination modes to link metal ion: bidentate chelating, bis-monodentate, monodentate. Compound 1 has 3-connected metal–organic framework with the (63) topology notation; Compounds 2 and 3 are one-dimensional chain structures. The luminescent properties for compound 1 was investigated. 相似文献
13.
N-[2-(8-heptadecenyl)-4,5-dihydro-1H-imidazole-1-ethyl]-2-bromoisobutyramide (IEB) was synthesized and characterized by elemental
analysis, FT-IR, and 1H NMR. It had been successfully used as a bidentate initiator for the ATRP of methyl methacrylate with CuBr/2,2′-bipyridine
as the catalyst, and N,N-dimethylformamide as the solvent at 70 °C. The kinetics was first order in monomer and the number-average molecular weight
of the polymer increased linearly with the monomer conversion, indicating the ‘living’/controlled nature of the polymerization.
The polymerization reached high conversions producing polymers with a low molecular weight distribution (
M
w/M
n = 1.319). The obtained poly(methylmethacrylate) (PMMA) functionalized with 2-(8-heptadecenyl)-4,5-dihydro-1H-imidazoleyl
and ω-Br as the end groups were characterized by FT-IR spectroscopy. They can be used as macroinitiators for chain extension
reaction. Then, PMMA coatings were grafted from iron substrates by surface-initiated ATRP from a surface-bound IEB initiator.
The EIS measurements confirmed the successful grafting of the polymer coatings. Greatly improved short-term anticorrosive
properties for PMMA-modified electrodes were demonstrated by substantially increased resistance of the film for a period of
24 h as compared to bare iron. 相似文献
14.
Lakhya J. Borthakur Tirthankar Jana S. K. Dolui 《Journal of Coatings Technology and Research》2010,7(6):765-772
A series of core–shell polymeric particles with poly(n-butyl acrylate-co-methacrylic acid-co-ethylene glycol dimethylacrylate) as core and poly(styrene-co-methyl methacrylate) as shell were prepared by seeded emulsion polymerization. The role of ethylene glycol dimethylacrylate
(EGDMA) is to crosslink the core so as to avoid any probability of gel formation and to bind both the core and the shell phase
together. The spherical morphology of the core–shell structure was achieved at 60:40 core to shell ratio. The core–shell morphology
was confirmed by SEM and TEM analyses. GPC analysis of the particles reveals that the polymer shows a bimodal mode. The first
peak has M
w = 382700 and M
n = 245200 with polydispersity index of 1.6, and the second peak has M
w = 21200 and M
n = 14800 with polydispersity index of 1.4. These core–shell latexes were applied as a pigment/binder in emulsion paint and
the paint properties like gloss, rock hardness, washability, opacity, etc. were compared with the standard. The results show
that these core–shell latexes can provide similar hiding power with 17% reduction of TiO2 in the paint formulation. 相似文献
15.
Reversible addition-fragmentation chain transfer (RAFT) polymerization of four divinyl monomers, 1,4-butanediol diacrylate (BDDA) and three poly(ethylene glycol) diacrylates (PEGDAs), were investigated under dilute conditions ([M] = 0.2-0.05 mol/L). RAFT polymerization of BDDA using a dithiocarbamate-type chain transfer agent (CTA) afforded soluble polymers, whereas a cross-linked product was obtained by conventional radical polymerization. The monomer concentration, the nature of the CTA, and the CTA/initiator ratio were found to affect the polymerization behavior and structure of the resulting polymers, which is attributed to the relative propensities for intermolecular propagating/cross-linking reactions and intramolecular cyclization. RAFT polymerizations of three PEGDAs (PEG258DA, average Mn = 258; PEG575DA, average Mn = 575; PEG700DA, average Mn = 700) having different lengths of PEG spacers (n = 3, 10, 13, respectively) were also conducted under dilute conditions. Water-soluble polymers were synthesized by one-step RAFT polymerization of PEGDAs having longer spacers (n = 10 and 13), whereas RAFT polymerization of PEGDA (n = 3) afforded polymers soluble in organic solvents. The product obtained by RAFT polymerization of PEGDA (n = 10) showed a characteristic thermoresponsive property, lower critical solution temperature (LCST), in aqueous solution. 相似文献
16.
Alaa S. Abd-El-Aziz Elizabeth A. Strohm Man Ding Rawda M. Okasha Tarek H. Afifi Sibel Sezgin Paul R. Shipley 《Journal of Inorganic and Organometallic Polymers and Materials》2010,20(3):592-603
A series of star-shaped macromolecules bearing distinct symmetrical branches with alternating organoiron complexes and azobenzene
moieties were synthesized using both convergent and divergent approaches. The various azo dye and organoiron-containing branches
were reacted with multifunctional cores via metal-mediated nucleophilic aromatic substitution and ester condensation reactions
to afford multi-substituted three- and four-arm star-shaped oligomers. UV–vis spectral studies of complexes 15 and 22 (λ
max = 435 and 427 nm, respectively) show bathochromic shifts (λ
max = 576 and 558, respectively) at various HCl concentrations indicating their use as potential acid sensors. Cyclic voltammetric
studies of the octa-iron oligomer 22 were reversibly reduced at E
1/2 = −1.53 V. 相似文献
17.
Li Yan Chuan-Bi Li Dong-Sheng Zhu Lin Xu 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(1):235-243
Two novel metal–organic coordination polymers {[Pb(CIPT)(1,4-BDC)]·2H2O}
n
1 and {[Zn2(IPDT)2(1,4-BDC)2(H2O)].3H2O}
n
2 [CIPT = 2-(3-chlorophenyl)-1H-imidazo[4,5-f][1,10]phenanthroline, 1,4-BDC = terephthalic acid, IPDT = 4-(1H-imidazo[4,5-f][1,10]phenanthroline-2-yl)-2,6-dimethoxyphenol]
were obtained from hydrothermal reaction and characterized by elemental analysis, thermogravimetric (TG) analysis, IR and
single-crystal X-ray diffraction. Both of the two coordination polymers exhibit one-dimensional (1D) infinite chain structures
through non-covalent interactions, and the existence of hydrogen bonds interactions lead the 1D chain to 2D layer structures.
It is noteworthy that the existence of hydrogen bonds reinforces the structural stability of the complexes 1 and 2, which can be proved by TG analysis. The photoluminescent study of coordination polymer 1 shows that it exhibits fluorescent emission band at 637 nm, which is red-shifted by 46 nm relative to the free ligand CIPT. 相似文献
18.
The kinetics of the thermal decomposition reaction of diethylketone triperoxide (3,3,6,6,9,9-hexaethyl-1,2,4,5,7,8-hexaoxacyclononane,
DEKTP) in ethylbenzene solution were studied in the temperature range of 120.0–150.0 °C and at an initial concentration range
of 0.01–0.10 M. This peroxide was used as a new initiator in methyl methacrylate (MMA) polymerization process at high temperatures
(110.0–140.0 °C) in ethylbenzene solution. The effects of initiator concentration and reaction temperature on the polymerization
rate were investigated in detail. Thus, activation parameters of the solution polymerization process (ΔE
d* = 83.3 kJ mol−1 and ΔE
p* − ΔE
t*/2 = 54.0 kJ mol−1) will be obtained. DEKTP can effectively act as initiator in MMA polymerization and its performance is similar to that presented
by a multifunctional initiator resulting in high-molecular weight polymethylmethacrylate with a high reaction rate. 相似文献
19.
Li Yan Chuan-Bi Li Dong-Sheng Zhu Lin Xu 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(2):395-403
Two novel metal–organic coordination polymers {[Pb2(MIP)2(BDC)2]·H2O}
n
1 and [Cd(MIP)(NDC)]
n
2 [MIP = 2-(3-methoxyphenyl)-1H-imidazo [4,5-f] [1, 10] phenanthroline, BDC = terephthalic acid, NDC = naphthalene-1,4-dicarboxylic
acid] were obtained from hydrothermal reaction and characterized by elemental analysis, thermogravimetric (TG) analysis, infrared
spectrum (IR) and single-crystal X-ray diffraction. The coordination polymers crystallize in triclinic, space group P-1 with a = 1.0335(2), b = 1.4224(3), c = 1.8156(4) nm, β = 106.088(3)° for complex 1 and the complex 2 crystallizes in monoclinic, space group P2(1)/n with a = 1.2562(8), b = 1.4800(9), c = 1.3723(8) nm, β = 97.257(1)°, respectively. The metal ions Pb(II) are located in [:PbN2O4] pentagonal bipyramidal geometry in complex 1. The metal ions Cd(II) in complex 2 act as distorted octahedral geometry, being surrounded by four carboxylate oxygen atoms from three NDC ligands and two donor
nitrogen atoms from one MIP molecule. Moreover, there are hydrogen bonds in the two complexes, and it is noteworthy that the
existence of hydrogen bonds and π–π interactions reinforce the structural stability of the title complexes, which have been
proved by TG analysis. The luminescent properties for the ligand MIP, NDC and complex 2 are also discussed in detail. 相似文献
20.
Ling-Ling Yu 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(1):278-282
Two new metal–organic coordination polymers containing Mn(II) and Cd(II) with oxo-bridged and N-donor ligands, [Mn(oba)(2,2′-bipy)]
n
(1) and {[Cd(oba)(bib)]·H2O}
n
(2) [2,3′-H2oba = 2-(3-carboxyphenoxy)benzoic acid, 2,2′-bipy = 2,2′-bipyridine, and bib = 4,4′-bis(2-methylimidazole-1-ylmethyl)biphenyl],
have been prepared and characterized by elemental analysis, Fourier infrared spectroscopy, and X-ray diffraction. Complex
1 has a 3D supramolecular network constructed from 1D zigzag chain via π–π stacking interactions. Complex 2 features 1D ladder-like chain which consists of 1D helical arrays and bib pillars. Moreover,
photoluminescence properties of the bib ligand and the Cd(II) complex were investigated. 相似文献