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1.
A cyclic oligosaccharide derivative was synthesized by cationic ring-opening polymerization of an anhydrodisaccharide derivative under high vacuum in dichloromethane with 20 mol% of PF5 as initiator. Analysis of the spectral results showed that the oligomer chain is composed of only 3 glucose units connected by -1,6 linkages with a glucopyranosyl branching unit at C-4 of each sugar residue in the main chain. 相似文献
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We have studied on the solubilization of single-walled carbon nanotubes (SW-CNTs) into aqueous and organic media by the use of a variety of nanometer size-controlled fluorinated self-assemblies, which were formed by the aggregations of end-capped fluoroalkyl segments in fluoroalkyl end-capped acrylic acid oligomers [RF-(ACA)n-RF], N,N-dimethylacrylamide oligomers [RF-(DMAA)n-RF], acryloylmorpholine oligomers [RF-(ACMO)n-RF], and N-(1,1-dimethyl-3-oxobutyl)acrylamide oligomers [RF-(DOBAA)n-RF]. Fluorinated self assemblies formed in organic media (colorless solutions) could solubilize SW-CNTs into organic media to afford the transparent pale yellow solutions. The dynamic light scattering measurements showed that the size of fluorinated self-assemblies increased after the solubilization of SW-CNTs into organic media. It was suggested that the solubilization of SW-CNTs into organic media is due to the encapsulation of SW-CNTs into fluorinated assemblies. Fluorinated assemblies were also able to solubilize SW-CNTs into water to give the transparent gray solutions. Among a variety of fluorinated assemblies, fluorinated assemblies formed by RF-(ACMO)n-RF [RF = CF(CF3)OC6F13] oligomer was more effective for the solubilization of SW-CNTs into both aqueous and organic media. Contact angle measurements of dodecane and the fluorescence spectra for poly(methyl methacrylate) cast film modified by fluorinated self-assemblies—SW-CNTs complexes showed that SW-CNTs are dispersed above the PMMA surface. 相似文献
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Some organogermanium oligomers with different side groups were synthesized via li-gand substitution polymerization from 1, 4-dioxane complex of germanium dichloride withdifferent organolithitum compounds. The oligomers were isolated through either precipi-tation from methanol or extraction using toluene with a yield of no less than 50%. Theweiglit average molecular weight (M_w) of the oligomers is ranging from 1.4×10~3 to 5.9×10~3depending on the type and alkyl length of the organolithium compounds used. 相似文献
5.
液体色谱,凝胶色谱分析低聚芳砜及其双烯大分子单体 总被引:2,自引:0,他引:2
本文用液相色谱和凝胶色谱对双酚A、双酚S型低聚芳砜及α,ω-双甲基丙烯酸聚芳砜酯大分子单体进行了组分分析,通过改合成条件、测定数均分子量等辅助手段确定液相色谱各峰的归属,计算其分子量及分子量分布指数,并对两种方法测定的结果进行了比较。用液相色谱观察低聚体每个组分的含量及其反应过程中的消长情况比凝胶色谱清晰。 相似文献
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环状碳酸酯低聚物的合成及其开环聚合的研究 总被引:4,自引:0,他引:4
环状碳酸酯低聚物的合成及其开环聚合的研究陈雨萍魏玮李革(中国科学院化学研究所工程塑料国家重点实验室北京100080)关键词环状碳酸酯低聚物,聚碳酸酯,开环聚合环状单体的开环聚合在合成高聚物方面具有突出的优点,即在聚合过程中没有副产物、热效应低、聚合... 相似文献
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Tetsuro Ito Toshiyuki TanakaMunekazu Iinuma Ibrahim IliyaKen-ichi Nakaya Zulfiqar AliYoshikazu Takahashi Ryuichi SawaYoshiaki Shirataki Jin MurataDedy Darnaedi 《Tetrahedron》2003,59(28):5347-5363
Five new resveratrol oligomers; pauciflorols A-C (1-3), isovaticanols B (6) and C (8), and three new oligostilbene glucosides; pauciflorosides A (11), B (13), C (14), were isolated from the stem bark of Vatica pauciflora (Dipterocarpaceae) together with known 17 resveratrol oligomers (4, 5, 7, 9, 10, 12 and 15-25) and bergenin (26). The structures of isolates were established on the basis of detailed spectroscopic analysis. The typical and characteristic spectral properties of some resveratrol oligomers were also discussed. 相似文献
9.
Lifang Yang Haifeng He Hongqing Cao Xinhua Wan Qi-feng Zhou Department of Polymer Science & Engineering College of Chemistry & Molecular Engineering Peking University Beijing China 《高分子科学》2002,(5):401-407
Four new rod-coil diblock molecules, which had well-defined para-phenylene oligomers (PPP, from biphenyl toquinquephenyl) as rigid segments and poly(ethylene oxide) (PEO, M_w ca. 750) as flexible segments, were synhesized. Thechemical structure and the number of repeating unit in PEO coil and PPP rod were characterized by ~1H-NMR and MALDI-TOF mass spectromeny. The diblock oligomers showed good solubility in common organic solvents and aggregated in wateras characterized by a blue shift in UV-vis absorption spectra, a red shift in emission spectra, quenching of the fluorescenceand formation of the microfibrilla and fractal-like structures. The formation of different supramolecular structures meant thatthis effort might lead to commercial important highly organized functional materials. 相似文献
10.
Yoshitsugu Kojima Takaaki Matsuoka Norio Sato Hideroh Takahashi 《Journal of polymer science. Part A, Polymer chemistry》1995,33(17):2935-2940
New conjugated oligomers were prepared by reacting phenylacetylene under high pressure of 0.11 to 0.92 GPa at 100–200°C for 0–5 h. The number-average molecular weight M?n, the weight-average molecular weight M?w, and the oligomer yield increased with pressure, tem-perature, and time. The average molecular weight of the oligomer showed the maximum value (M?n: 830, M?w: 2400) under 0.92 GPa, the maximum pressure, where phenylacetylene was oligomerized at a constant temperature. The structure of the oligomer was investigated from ESR, infrared, UV–VIS, field desorption mass (FDMS) spectra, and 13C NMR spec-trum. Analysis of the FDMS spectrum revealed that the molecular weight of the oligomer was multiple of the monomer. 13C NMR spectrum of the oligomer showed the absence of sp-carbon (? C?). We found that the oligomer had a cyclic structure. The cyclic oligomers of pentamer or more were new compounds. © 1995 John Wiley & Sons, Inc. 相似文献