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TheSynthesisofPoly(ethyleneoxide)┐Block┐Polybutylacrylate**SupportedbytheNationalNaturalScienceFoundationofChinaandDoctoralfo... 相似文献
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Synthesis of poly(ethylene oxide) (PEO) macromonomers carrying a methacyloyl group in one end, and N, N-dimethyl amino, thiophene, styryl and vinyl ether functional groups in the other end was desribed. The general synthetic strategy is based on the living anionic polymerization of ethylene oxide initiated with functional potassium alcoholates, followed by reaction with methacyloyl chloride. These macromonomers were further utilized in various macromolecular architectures through via concurrent or selective thermal free radical, oxidative and photoinitiated free radical and cationic polymerization methods. The use of this synthetic route to prepare graft copolymers possessing completly and perfectly alternating PEO side chains using charge-transfer-complex polymerization was also demonstrated. 相似文献
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Avinash Dundigalla Sheng Lin‐Gibson Vincent Ferreiro Matthew M. Malwitz Gudrun Schmidt 《Macromolecular rapid communications》2005,26(3):143-149
Summary: The unusual structure of poly(ethylene oxide) (PEO) and Laponite clay in transparent nanocomposite films was investigated using scanning electron, atomic force, and optical microscopy, and X‐ray scattering. Each method is sensitive to different aspects of structural features and together they measure the resulting morphology and shear‐induced orientation. On nanometer length scales, clay platelets were found to orient in bundles while polymer crystallinity was suppressed. Microscopy led to the observation of unexpected and highly oriented multilayers on the micron length scale.
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Memory effects of several copolymers of poly(ethylene oxide) (PEO) and poly(ethylene terephthalate) (PET) were illustrated with photos, determined with shrinkage experiments and characterized by the recovery of samples to their original figures. Copolymers of appropriate composition could undertake an approximately full recovery which is tightly related to the annealing temperature at which shrinkage of samples occurs to some extent. Melting and recrystallization of PEO segments may be responsible for the memory effect. The memory properties of samples almost kept unchanged after many fatigue cycles (e.g. 15–20 cycles), which could make these copolymers useful in practical applications as novel shape memory materials. © 1997 John Wiley & Sons, Ltd. 相似文献
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Kaynoush Naraghi Bernard Meurer Pierre J. Lutz 《Macromolecular rapid communications》2005,26(7):537-541
Summary: Hydrogels, the elastic chains of which are constituted of a short central poly(1,3‐dioxolane) (PDXL) block surrounded by two hydrophilic poly(ethylene oxide) (PEO) blocks, were obtained by free radical homopolymerization of α,ω–methacryloyloxy PEO‐block‐1,3‐PDXL‐block‐PEO macromonomers. The central PDXL block is known to be sensitive to acidic degradation due to the presence of acetal groups. Once swollen to equilibrium, these hydrogels were characterized for their equilibrium swelling degree and their mechanical properties and network degradation studies were carried out.
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A kinetic study of the crystallization of poly(ethylene oxide) (PEO) and of a blend of PEO+poly(bisphenol A-co-epichlorohydrin)
(PBE) was performed by using DSC in a non-isothermal program at constant cooling rates. The curves obtained were analyzed
by the Kissinger, Ozawa and Friedman methods, with determination of the kinetic parameters in each case. As a consequence
of the presence of PBE, the kinetic parameters were altered, leading to the conclusion that PBE has some influence on the
crystallization of PEO, modifying its mechanism.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
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Well‐defined poly(ethylene oxide)s (PEOs) bearing reactive sites regularly distributed along the chain have been synthesized by the polycondensation of PEO containing a central tertiary amino group with dichloromethane, followed by quaternization with suitable reagents to obtain polyzwitterionic or cationic PEOs with alkyl, allyl, or fluorocarbon pendant groups. The pendant allyl groups have been converted into primary amino groups by reaction with 2‐aminoethanethiol hydrochloride to obtain polyamino‐functionalized PEO.
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Christophe Flesch Yves Unterfinger Elodie Bourgeat‐Lami Etienne Duguet Christelle Delaite Philippe Dumas 《Macromolecular rapid communications》2005,26(18):1494-1498
Summary: A methacrylate‐functionalized poly(ethylene glycol) macromonomer was copolymerized at the surface of methacrylate‐derivatized maghemite nanoparticles. After silylation of the magnetic core with methacryloxypropyltrimethoxysilane, two grafting procedures based on either a direct copolymerization reaction in water or an inverse emulsion polymerization were compared. A direct copolymerization led to low polymer surface amounts, whereas an inverse emulsion process allowed nanocomposite particles containing up to 90 wt.‐% polymer to be obtained.
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Sherry Lee Xia Zhong Roya Ravarian Peter Valtchev Fariba Dehghani 《Journal of polymer science. Part A, Polymer chemistry》2014,52(9):1291-1299
The synthesis and purification of poly(lactide ethylene oxide fumarate) (PLEOF) involved using organic solvents and triethylamine, an acid scavenger that produces toxic complexes. These issues were addressed by using potassium carbonate as an alternative acid scavenger and CO2 gas expanded solution as a media for reaction. Conducting the reaction at these conditions resulted in reducing the number of stages for purification, enhancing the yield of polymerization by 31%, and increasing the fumarate fraction by 110% compared with conventionally produced polymers. Therefore, the capacity of polymer for crosslinking was significantly promoted that resulted in elevating the compression modulus of hydrogel by 119%. Eliminating the toxic chemical residues and strengthening the mechanical property of PLEOF led to enhancement in primary osteoblast cell proliferation on this hydrogel. The new strategy for the synthesis of PLEOF had paramount impact on the characteristics of this polymer and enhanced its biocompatibility for tissue engineering applications, particularly bone repair. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1291–1299 相似文献
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Sterling F. Alfred Zoha M. Al‐Badri Ahmad E. Madkour Karen Lienkamp Gregory N. Tew 《Journal of polymer science. Part A, Polymer chemistry》2008,46(8):2640-2648
The synthesis of three different poly(ethylene oxide) macromonomers with a norbornene and oxanorbornene end group is presented. The macromonomers were polymerized to comb‐polymers by ring‐opening metathesis polymerization (ROMP) using Grubbs' Catalyst G3 to produce water soluble polymers with polydispersities between 1.04 and 1.30 and molecular weights between 14,000 and 50,000 g/mol. Characterization by static and dynamic light scattering reveals that the comb‐polymers with norbornene backbone are molecularly disperse in aqueous solution, while the oxanorbornene‐backbone polymers form small water‐soluble aggregates. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2640–2648, 2008 相似文献
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The self-diffusion of poly (ethylene oxide)-poly (propylene oxide)-poly (ethylene oxide) block copolymers dissolved in deuterated water was investigated by means of pulsed field gradient NMR (PFG-NMR). The polymer forms micelles in the solution and, with increasing temperature, clouding and phase demixing occurs. The self-diffusion coefficient indicates the association of the polymer molecules in the vicinity of the cloud point because of its maximum with increasing temperature. Above the cloud point, two kinds of diffusing species are observed due to phase separation. The faster diffusing species is attributed to the polymer-poor phase. The self-diffusion coefficient of the polymer-rich phase species decreases with increasing temperature above the cloud point due to further association and dehydration. The correlation length of the diffusing associates, calculated from the self-diffusion coefficient and the viscosity by means of the Stokes-Einstein equation is nearly independent of temperature and concentration up to 30 wt-% polymer concentration. The correlation length is about 1.4 nm. It shows a slight maximum at the cloud point. 相似文献
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Eliane Alexandre Jacques Cinqualbre Daniel Jaeck Lysiane Richert François Isel Pierre J. Lutz 《Macromolecular Symposia》2004,210(1):475-481
Macromonomer based poly(ethylene oxide) (PEO) hydrogels were tested with respect to their ability to serve as a template for the survival and the growth of hepatocytes. Two systems were considered : either the surface of preexisting hydrogels, with controlled structural parameters, were seeded with isolated rat hepatocytes or the hepatocytes were dispersed in physiological medium containing the macromonomer/initiator and heated to 37°C. In the first case, cells were examined at given times after spreading over two days. The results were compared to those observed for the dispersion of fibroblasts onto a surface of the same type of hydrogels. The effects of the structure of the hydrogels and its chemical nature on the extent of hepatocyte attachment (or encapsulation) and the morphology were investigated. 相似文献
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Blends composed of sulfonated polysulfone (SPSF) and poly(ethylene oxide)-grafted-polyethersulfone (PEO-g-PES) in different compositions have been prepared and studied in terms of fuel cell relevant parameters like thermal behaviour, water uptake and ionic conductivity. Moreover, spectroscopic characterization (FT-IR) has also been conducted in order to elucidate their miscibility and to investigate the influence of polymer blending on the crystallinity level of the individual components. These blends exhibit very good mechanical properties, a very high water uptake and a high ionic conductivity (4 × 10−3 S/cm) at ambient temperatures and they are amorphous, a property that facilitates their use as polymer electrolytes in fuel cells. 相似文献
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Johann Kwiatkowski Andrew K. Whittaker 《Journal of Polymer Science.Polymer Physics》2001,39(14):1678-1685
Motion of chains of poly(ethylene oxide) within the interlayer spacing of 2:1 phyllosilicate/montmorillonite was studied with 1H and 13C NMR spectroscopy. Measurements of the 1H NMR line widths and relaxation times across a large temperature range were used to determine the effect of bulk thermal transitions on polymer chain motion within the nanocomposites. The results were consistent with previous reports of low apparent activation energies of motion. Details of the frequency and geometry of motion were obtained from a comparison of the 13C cross‐polarity/magic‐angle spinning spectra and relaxation times of the nanocomposite with those of the pure polymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1678–1685, 2001 相似文献
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Guowei Wang Xiaolan Luo Yannan Zhang Junlian Huang 《Journal of polymer science. Part A, Polymer chemistry》2009,47(18):4800-4810
The dendrimer‐like copolymers [PEEGE‐(PS/PEO)]n (n ≥ 2) based on the star[Polystyrene‐Poly(ethylene oxide)‐Poly(ethoxyethyl glycidyl ether)] [star(PS‐PEO‐(PEEGE‐OH))] terpolymers were synthesized by click chemistry. First, the star‐shaped copolymers star[PS‐PEO‐(PEEGE‐Alkyne)] (also termed as [PEEGE‐(PS/PEO)]1) were synthesized by the reaction of hydroxyl end group at PEEGE arm (on star[PS‐PEO‐(PEEGE‐OH)]) with propargyl bromide. Then, the small molecule 1,4‐diazidobutane (DAB) with two azide groups and pentaerythritol tetrakis (2‐azidoisobutyrate) (PTAB) with four azide groups were synthesized and reacted with [PEEGE‐(PS/PEO)]1 by the click chemistry for dendrimer‐like [PEEGE‐(PS/PEO)]2 and [PEEGE‐(PS/PEO)]4, respectively. However, in the latter case, only the [PEEGE‐(PS/PEO)]3 was formed as the main product because of the steric effect. The final dendrimer‐like [PEEGE‐(PS/PEO)]n copolymers were characterized by SEC and 1H‐NMR in detail. Comparing with the SEC of their precursor [PEEGE‐(PS/PEO)]1, the curves of [PEEGE‐(PS/PEO)]2 was shifted to the shorter elution time, while that of [PEEGE‐(PS/PEO)]n (n ≥ 3) was shifted to the longer elution time, which was attributed to the different hydrodynamic volume derived from their separate structures and compositions in THF solution. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4800–4810, 2009 相似文献