The Synthesis of Poly(ethylene oxide)-Block-Polybutylacrylate

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Study of the Crystallization Kinetics. Poly(ethylene oxide) and a blend of poly(ethylene oxide) and poly(bisphenol A-co-epichlorohydrin)

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.     

Synthesis of Poly(ethylene oxide)s Bearing Functional Groups along the Chain

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.

Polyfunctional PEOs bearing different pendant groups.     

Shape Memory Properties in Poly(ethylene oxide)–Poly(ethylene terephthalate) Copolymers

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.     

Molecular motion in nanocomposites of poly(ethylene oxide) and montmorillonite

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     

Calculation of polymer blend compositions from vibrational spectra: A simple method

In this work, the application of a new approach for quantitative analysis, originally developed for Raman spectroscopy, is extended to IR spectroscopy. The attractive features of this methodology are its simplicity and ease of use in comparison with traditional approaches. Unlike other methods, rich spectral information containing several overlapped peaks can be used in the calculations. A robust and well‐conditioned calculation scheme renders precise results, which are independent of the operator's decisions. The method was applied to study the chemical compositions of homogeneous polymer blends made of polystyrene and poly(vinyl methyl ether). Raman and IR blend spectra were acquired with confocal Raman microspectroscopy and attenuated total reflection/Fourier transform infrared, respectively. The blend compositions were calculated from the corresponding vibrational spectra with the proposed strategy, and excellent agreement between those values and the true ones was found for both techniques. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1144–1151, 2005     

Gas Chromatographic Analysis in the Synthesis of Poly (Ethylene Oxide) Dimethyl Ethers

ABSTRACT

Gas chromatography (GC) was used in the analysis of the synthesized oligomeric mixtures, involving poly(ethylene glycol)s, poly(ethylene oxide) monomethyl ethers, poly(ethylene oxide) dimethyl ethers and crown ethers. It was demonstrated that the samples could be successfully analyzed on the wide bore capillary column with cross-linked polar stationary phase (FFAP) without derivatization. An on-column injection technique is used to avoid possible sample distortion. Identification and quantitative analysis were achieved taking advantage of the GC homologues retention rule and the FID effective carbon number response rule, thus the limitations of some standard availability and purity problems were avoided. Much useful information such as average molecular weight, polydisperse distribution and so on were obtained by the established method, which is very important in the process monitoring and product quality control.     

PEO-PS共聚微粒在MgSO4溶液中聚集的分形

可溶性高聚物的聚集动力学研究在物理、化学、生物和医学工程等诸多领域都极有理论和实际应用价值，这方面的工作国外多有报导［‘，’，“］．最近Napper与他的合作者Zhu又报导用聚地异丙基丙烯酸胺（PNIPAM）空间稳定的聚苯乙烯（PS）微乳粒子在NaNO。中的聚集动力学研究［‘’］．指出该粒子的聚集生长遵循指数规律，聚集速率和描述生长过程的分形值（fractal山mension）随着NaNO。的浓度和温度增加·在所研究的条件范围内粒子的聚集过程属扩散限制型簇聚集（dffesion－h。tedclusteraggregation，DLCA．本文将报导用不同摩to＄…     

Blends of Sulfonated Polysulfone and Poly(ethylene oxide)-Grafted-Polyethersulfone as Proton Exchange Membranes for Fuel Cell Applications

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.     

Polybenzoxazole from 1,4-bis(trichloromethyl)benzene

High molecular weight poly(phenylenebenzobisoxazole) (PBO) was synthesized from 1,3-diamino-4,6-dihydroxybenzene dihydrochloride (1) and 1,4-bis(trichloromethyl)benzene (3) in polyphosphoric acid (PPA) or a mixture of PPA and methanesulfonic acid. When PPA was used as the solvent, 3 was first converted in situ to terephthalic acid before 1 was added to minimize degradation of 1. Compound 3 did not need to be sealed from atmospheric moisture because the trichloromethyl groups were not moisture sensitive. It was not necessary to use micronized 3. Adjustment of P₂O₅ content was optional for this reaction because no water was liberated from the condensation of 1 and 3. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2143–2145, 1997     

Poly(ethylene terephthalate) copolymers containing 5‐nitroisophthalic units. II. Crystallization studies

The microstructure and crystallization behavior of a set of poly(ethylene terephthalate‐co‐5‐nitroisophthalate) copolymers (PETNI) containing 5‐nitroisophthalic units in the 10–50 mol % range were examined and compared to those of poly(ethylene terephthalate) (PET) and poly(ethylene terephthalate‐co‐isophthalate) (PETI) copolymers. A ¹³C NMR analysis of PETNI copolymers in a trifluoroacetic acid solution indicates that they are random copolymers with average sequence lengths in accordance with ideal polycondensation statistics. Differential scanning calorimetry (DSC) studies show that PETNI containing 5‐nitroisophthalic units up to 20 mol % are able to crystallize and that crystallization takes place in these copolymers at much slower rates than in PET. Wide‐angle X‐ray diffraction from powder and fibers reveals that crystallizable PETNI adopts the same triclinic crystal structure as PET, with the nitroisophthalate units being excluded from crystallites. Fourier transform infrared in combination with cross‐polarization/magic‐angle spinning ¹³C NMR spectroscopy demonstrates the occurrence of a gauche–trans conversion encompassing the crystallization process. A correlation between DSC and spectroscopic data leads us to conclude that the content of trans conformer in the noncrystallized phase of PETNI is higher than in both PET and PETI copolymers and suggests that secondary crystallization in the homopolymer must proceed by a mechanism different than that in copolymers. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1553–1564, 2001     

聚甲基丙烯酸甲酯/星形聚乙二醇半互穿聚合物网络的形状记忆性能和分子机理

采用非共价复合方法,设计并合成了具有星形结构的聚甲基丙烯酸甲酯/星形聚乙二醇半互穿聚合物网络(PMMA/SPEG)和聚甲基丙烯酸甲酯/线性聚乙二醇半互穿聚合物网络(PMMA/LPEG).研究了PEG分子量对PMMA/SPEG和PMMA/LPEG的热性能、机械性能、动态机械性能和形状记忆性能的影响.结果表明,与PMMA/LPEG相比,星形结构的嵌入显著提高了PMMA/SPEG复合物的机械性能、形状回复率和回复速度.采用Edwards管道模型理论对其形状记忆效应的分子机理进行了阐释,利用材料的应力松弛特性对机理分析进行了验证.     

聚左旋乳酸/聚氧化乙烯共混物的拉伸行为及结构转变

采用熔融共混方法制备了聚左旋乳酸(PLLA)和超高分子量聚氧化乙烯(PEO)共混物, 通过差示扫描量热(DSC)、 扫描电子显微镜(SEM)和二维广角X射线散射(2D-WAXS)等方法系统研究了PEO的加入对不同温度下PLLA拉伸行为及拉伸过程中微观结构变化的影响. 结果表明, PLLA/PEO共混物为非均相体系, PEO粒子均匀分布在PLLA中形成两相结构. PEO的加入能够显著降低PLLA的玻璃化转变温度(T_g), 在25～60 ℃范围内显著提高PLLA的拉伸性能. 在60 ℃拉伸时, PEO的加入提高了PLLA在拉伸过程中的结晶和形变能力. 在80 ℃拉伸时, 共混物的拉伸断裂伸长率下降, 但共混物的结晶速度仍高于纯PLLA样品.     

Poly(ethylene terephthalate) copolymers containing nitroterephthalic units. I. Synthesis and characterization

The synthesis, microstructure, and thermal behavior of a series of poly(ethylene terephthalate) (PET) copolymers containing nitroterephthalic units are described. These novel copolyesters were synthesized by transesterification followed by melt copolycondensation of dimethyl terephthalate and dimethyl nitroterephthalate mixtures with ethylene glycol. The molar ratio of the two comonomers in the feed varied from 95/5 to 25/75. Furthermore, PET and poly(ethylene nitroterephthalate) homopolymers were synthesized with the same method and comparatively studied. Copolyester compositions were practically the same as in the feed, and weight‐average molecular weights ranged from 10,000 to 60,000. The two monomeric units were randomly distributed along the polymer chain, and the experimentally determined average sequence lengths were in accordance with ideal copolycondensation statistics. Melting temperatures and enthalpies of the copolyesters decreased with increasing content in nitroterephthalic units, and they all showed a single glass‐transition temperature superior to that of PET. They appeared to be stable up to 300 °C, and thermal degradation occurred in two well‐differentiated steps. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3761–3770, 2000     

Morphology and crystal structure of the poly(ethylene oxide)–hydroquinone molecular complex

The occurrence of a molecular complex between poly(ethylene oxide) (PEO) and p‐dihydroxybenzene (hydroquinone) has been determined using different experimental techniques such as differential scanning calorimetry (DSC), wide‐angle X‐ray diffraction (WAXD), and Fourier transform infrared spectroscopy (FTIR). From DSC investigations, an ethylene oxide/hydroquinone molar ratio of 2/1 was deduced. During the heating, the molecular complex undergoes a peritectic reaction and spontaneously transforms into a liquid phase and crystalline hydroquinone (incongruent melting). A triclinic unit cell (a = 1.17 nm, b = 1.20 nm, c = 1.06 nm, α = 78°, β = 64°, γ = 115°), containing eight ethylene oxide (EO) monomers and four hydroquinone molecules, has been determined from the analysis of the X‐ray diffraction fiber patterns of stretched and spherulitic films. The PEO chains adopt a helical conformation with four monomers per turn, which is very similar to the 7₂ helix of the pure polymer. A crystal structure is proposed on the basis of molecular packing considerations and X‐ray diffraction intensities. It consists of a layered structure with an alternation of PEO and small molecules layers, both layers being stabilized by an array of hydrogen bonds. The morphology of PEO–HYD crystals was studied by small angle X‐ray scattering and DSC. As previously shown for the PEO–resorcinol complex, PEO–HYD samples crystallize with a lamellar thickness corresponding to fully extended or integral folded chains. The relative proportion of lamellae with different thicknesses depends on the crystallization temperature and time. Finally, the observed morphologies are discussed in terms of intermolecular interactions and chain mobility. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 1197–1208, 1999     

Poly(ethylene oxide) blends with crosslinking polyester resin

The miscibility of polyethylene oxide (PEO) with oligoester and polyester resin, the morphology of the blends and the kinetics of PEO crystallization in the blends were studied by optical microscopy and differential scanning calorimetry. The blends were found to be miscible with uncured resin at 60°C. After isothermal crystallization of PEO from liquid oligoester or UV cured polyester about 20% of the PEO material is still dissolved in the resin and it is incorporated between lamellae or in the interspherulitic regions. It was observed that the growth rate of PEO spherulites and the degree of crystallinity of PEO in the blends decreases very fast together with a decrease of the PEO content and the progress of the resin crosslinking.