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自从Tomalia和Newkome报道树枝形聚合物以来[1],树状分子的研究主要集中在它的合成与表征上.二十世纪80年代中期,出现了具有非常规整、精致和球形结构的树状大分子,其分子体积、形状和功能可在分子水平精确设计和控制.这些特征的结合应用在催化领域,将使树状大分子有可能消除均相催化与非均相催化之间的差别,发展出一类具有优异性能的催化剂.1994年Van Koten等[2]报道了首例树状分子金属配合物催化剂,它在催化研究领域的应用引起了人们极大的关注,并已取得很大的进展[3].与可溶性高分子负载催化剂相比,树状分子催化剂具有如下优点:1)可精… 相似文献
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高分子化合物化学的发展,不仅限于碳、氢的有机化合物。例如将硅代替大分子链结构中的碳,形成—Si—O—Si—型的高分子,它的性能就得到很大的改善。1937年开始研究有机硅化合物,1940年就合成了Si—O—Si型的高分子,而在侧链上带有有机基团,出现了名为聚有机硅氧烷这一类有机化合物。 相似文献
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树状大分子是一类高度支化的单分散性大分子,具有精确可控的分子结构.本文在树状大分子结构特点的基础上,阐述了以树状大分子为载体的新型纳米CT成像造影剂的合成及其在CT成像中的应用,并对树状大分子在CT成像中的发展趋势和应用领域进行了展望. 相似文献
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近年来, 刺激响应型超分子凝胶作为一类智能软物质材料, 在离子识别材料、自修复材料、生物材料和药物缓释等领域展现出了非常好的应用前景, 受到人们广泛关注. 树状分子是一类具有高度支化结构的大分子, 其形成的凝胶兼具有机小分子凝胶和聚合物凝胶的双重优点, 树状分子丰富的多层次支化几何结构有利于修饰不同功能基团, 从而确保各功能基团彼此独立作用而不相互干扰, 这种特性使其在构筑多功能化凝胶材料, 尤其是多重环境刺激响应型凝胶材料方面具有独特优势. 基于此, 本综述从树状分子凝胶因子设计、成凝胶机理、响应性能和响应机理等方面详细归纳了刺激响应型树状分子凝胶的研究进展. 按照刺激源不同, 主要从光响应型、氧化还原响应型、离子响应型、触变响应型和多重响应型五个方面对刺激响应树状分子凝胶进行了系统归纳总结. 最后, 基于目前刺激响应树状分子凝胶存在的一些问题对该领域未来发展进行了展望. 相似文献
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超支化聚合物是一类高度支化的具有三维椭球状立体构造的大分子[1]. 由于具有传统线型聚合物所没有的低熔体粘度、高流变性、良好的溶解性及大量末端官能团等一系列独特的物理化学特性, 超支化聚合物自 20世纪 80年代末在杜邦公司诞生以来[2]便很快成为高分子科学界研究的一个热点[3~7], 预计其将在医药载体、大分子建筑"砌块"、催化剂和流变添加剂等诸多领域得到广泛应用[8]. 相似文献
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树状大分子是近年来蓬勃发展的一类新型高分子材料, 其表面存在大量的官能团, 分子内部存在空腔且分子尺寸可控, 因此, 树状大分子已被广泛应用于众多的领域. 肽类树状大分子是指在树状大分子结构中含有肽键的一类大分子, 因其具有类似蛋白质一样的球状结构, 且具有优异的水溶性、生物相容性、生物降解性和细胞低毒性等特点, 所以, 肽类树状大分子可以作为药物传输的载体. 此外, 肽类树状大分子的疏水空腔可以装载疏水性药物, 对其起到增溶和缓释作用. 综述了肽类树状大分子的合成方法, 并对其与药物分子的结合机制及其在药物传输系统中的应用进行了总结与展望. 相似文献
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可光固化超支化聚硅氧基硅烷的合成与表征 总被引:1,自引:0,他引:1
自20世纪80年代末期Kim和Webster首次采用AB2型单体合成超支化聚合物以来,超支化聚合物以其新颖的结构、独特的性能和广泛的应用前景受到了科学界和工业界的广泛关注.其中超支化有机硅聚合物,尤其是硅氧基聚合物,由于具有良好的高低温稳定性、耐腐蚀性、耐候性等,以及硅氯、硅氢等末端基团易于功能化改性的特点,使其在功能性涂层材料、催化剂以及液晶材料等领域具有重要的应用价值.到目前为止,有关超支化聚硅氧基硅烷的研究主要集中在AB2型单体(x≥2,A和B分别为硅氢基团和乙烯基、烯丙基等不饱和基团)的制备以及硅氢加成产物的功能化改性方面. 相似文献
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The curing characteristics of carboxylic functionalized glucose resin (glucose maleic acid ester vinyl resin: GMAEV) and epoxy resin have been studied using DSC and FTIR methods. Exothermic reactions attributed to esterification and etherification reactions of the hydroxyl and carboxyl functionalities of GMAEV with the epoxy groups were identified. Exothermic reactions showed very different patterns according to the degree of carboxyl group substituent of GMAEV. The results showed that esterification reaction occurs in the early stage of cure and then etherification followed after completion of the esterification. A cured matrix containing epoxy resin and 50 wt.% of GMAEV was prepared and characterized. The cured matrix showed thermal stability up to 300 °C. The average glass transition temperature and storage modulus of the matrix were as high as 95 °C and 2700 MPa, respectively. The cured matrix of epoxy resin and GMAEV with higher degree of carboxyl group was found to have a lower density due to the formation of bulky groups in the crosslinks. 相似文献
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制备了一种含芳基噻唑基团热稳定环氧树脂材料(TDABZ),通过傅里叶变换红外光谱(FTIR)对其结构进行了表征,采用热重分析-微熵热重分析(TGA-DTG)计算了TDABZ的热分解动力学参数,利用热重分析(TGA)和动态热机械分析(DMTA)探讨了TDABZ的耐热性能。 结果表明,TDABZ通过TGDDM结构中的环氧基团与混合固化剂(DDS和2-ABZ)结构中的活泼氢反应,在较低的温度下就能完全交联固化。 通过Kissinger和Ozawa方法求得TDABZ的热分解活化能分别为205.5和221.9 kJ/mol。 TDABZ固化物具有优异的耐热性能,双悬臂梁法测得的玻璃化转变温度(Tg)达到242.3 ℃,在N2气气氛下失重5%对应的温度(Td5)为340.2 ℃,最大失重速率对应的温度(Tdmax)为395.5 ℃,600 ℃的质量保留率为24.1%,显著提高了环氧树脂的热稳定性能,拓宽了其应用领域。 相似文献
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The bisphenol A epoxy acrylate resin (EA) containing a small amount of layered double hydroxide (LDH) was cured within seconds under UV irradiation at ambient temperature. Its microstructure was characterized by X‐ray diffraction (XRD). The combustion behavior of the coating was examined by the Microscale Combustion Calorimeter (MCC) and limiting oxygen index (LOI). The results obtained from MCC and LOI indicated that the addition of LDH into EA could decrease the peak of heat release rate (HRR) for the films and increase the LOI value of the films. Thermal behavior of the cured films was studied by thermogravimetric analysis (TGA). The results for TGA indicated that with increase in the contents of LDH, the residual char of UV‐cured films increased at 600 °C. The evolved products for UV‐cured films were characterized using thermogravimetric analysis/infrared spectrometry (TGA‐IR). It was implied that the mechanism of thermal degradation for EA0 was different from EA4. Viscoelastic property of photo‐cured hybrid materials was evaluated by dynamic‐mechanical analysis. The effect of LDH on the properties of UV‐curable films was critically evaluated in this paper. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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2-(Diphenylphosphinyl)-1,4-benzenediol(DPO-HQ) was synthesized by the reaction of diphenylphos- phine oxide(DPO) with 1,4-benzoquinone(BQ), and characterized by Fourier transform infrared(FTIR), and nuclear magnetic resonance(1H NMR, 13C NMR, 31p NMR) spectrometries. The thermal stability of DPO-HQ was investi- gated by thermogravimetric analysis(TGA). Flame retardant epoxy resin was synthesized based on DPO-HQ. The thermal properties and burning performance of cured epoxy resins were measured by differential scanning calorime- try(DSC), thermogravimetric analysis(TGA), limited oxygen index(LOI) and vertical burning test(UL-94V). The morphologies of cured epoxy resins after combustion were investigated by scanning electron microscopy(SEM) and electron probe microanalysis(EPMA). Moreover, the thermal stability(both in air and in N2) of DPO-HQ and its cured epoxy resin was compared with that of 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10- oxide(DOPO-HQ) and its cured epoxy resin. The thermal stability of DPO-HQ is comparable with that of DOPO-HQ, while the thermal stability of cured epoxy resin based on DPO-HQ is better than that based on DOPO-HQ. 相似文献
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一种带肉桂酸酯基的聚酰亚胺液晶光定向材料研究 总被引:3,自引:0,他引:3
利用双酚A二胺单体(BISDA)与4,4-′(六氟异丙基)-双邻苯二甲酸酐(6FDA)的缩聚反应,制备了含有侧羟基的先驱聚合物PI-OH.通过PI-OH与肉桂酰氯的官能化反应,得到接有肉桂酸酯感光侧基的双酚A型聚酰亚胺PI-CI.用红外光谱(FTIR)、氢核磁共振(1H-NMR)分析、热分析(DSC)等方法表征了上述聚合物的结构和热性能.利用紫外-可见光谱(UV-Vis)对PI-CI的感光性能进行了研究.在线偏振紫外光辐照下,上述聚合物膜表现出二色向性.二向色性的强弱随光照能量的变化存在最大值.经线性偏振紫外光(LPUV)辐射后的PI-CI薄膜能诱导液晶盒中液晶分子发生均匀的定向沿面排列.上述实验表明,该聚酰亚胺是一类具有优良性能的潜在液晶光定向材料. 相似文献
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John N. Suman 《European Polymer Journal》2005,41(12):2963-2972
Bisphenol A dicyanate ester (BADCy) was modified with different amounts of an engineering thermoplastic, polysulfone (PS) to improve impact strength of the parent resin. Differential scanning calorimetry of the blends suggested that addition of PS widens the curing exotherm of the BADCy considerably. FTIR of cured neat resins indicated total conversion of cyanate functional groups into triazine rings by cyclotrimerization. The cured neat resins showed phase separated morphology with cyanate ester as the continuous phase. The modified resins were shown to have better thermal, hygrothermal and impact strength properties. However, when glass fiber reinforced composites were made using partially polymerized BADCy and PS, very little or no phase separation in the resin was noticed. Flexural and impact strength measurement of composites showed that PS modification has compromised the flexural properties and only retained the impact strength of the parent resin containing composite. This study thus suggests that improvements realized in thermoplastic modification of monomeric BADCy are not directly transferable to composites using a partially prepolymerized BADCy. 相似文献