共查询到18条相似文献,搜索用时 140 毫秒
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分散聚合技术及其研究进展 总被引:5,自引:0,他引:5
介绍了分散聚合体系中各组分及反应条件对反应过程和最终产物性能的影响,简要归纳了分散聚合成核机理、稳定机理及其反应动力学,并着重阐述了近年来分散聚合发展的新技术以及制备的功能微球在各领域的应用等方面的研究进展.分散聚合与其它非均相聚合方法相比,是制备粒径范围在1-10μm且单分散性较好的聚合物微球的有效方法.最近,许多新思路不断引入分散聚合体系,如采用水和超临界CO2作为分散介质,尝试微波和辐射引发聚合以及按照活性聚合机理进行反应等. 相似文献
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分散聚合法制备PVP微球的研究 总被引:1,自引:0,他引:1
以N-乙烯基吡咯烷酮(NVP)为初始单体,乙酸乙酯为分散介质,采用分散聚合法制备了分散性能良好、粒径为3~4μm的聚乙烯基吡咯烷酮(PVP)微球.考察了单体、分散剂及引发剂浓度对PVP微球的粒径、单体转化率及分子量的影响,并对PVP的结构和性能进行研究.结果表明,单体浓度增加,PVP微球粒径和分子量增大,单体转化率升高;分散剂浓度增加,PVP微球粒径变小,分子量增大,单体转化率升高;引发剂浓度增加,PVP微球粒径变大,分子量减小,单体转化率升高.与溶液聚合法相比,分散聚合法制备的PVP分子量较小且具有一定的结晶性. 相似文献
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乙酸乙酯/乙醇混合溶液中分散聚合制备单分散亚微米级聚丙烯酰胺微球 总被引:8,自引:0,他引:8
以乙酸乙酯/乙醇混合溶液为分散介质, PVP为分散剂, 通过分散聚合法合成了单分散亚微米级PAM微球. 在反应初期, 自动加速现象明显. 由于凝胶效应的影响, 分子量随着单体转化率的提高而逐渐增大. 考察了分散剂浓度对最终产物增率的影响, 并用IR光谱对产物的结构进行了表征, 证明分散聚合体系中吸附稳定机理和接枝稳定机理同时存在, 且以后者为主. 同时还研究了混合溶剂比例、分散剂浓度、初始单体浓度和引发剂浓度对微球粒径及粒径分布的影响. 结果表明, 乙酸乙酯/乙醇体积比在5∶5-7∶3范围内, 可得到粒径在200 nm左右, 且分布较窄的PAM微球; 分散剂浓度增大, 粒径减小; 引发剂浓度增加, 粒径增大; 初始单体浓度较高或较低时, 都得不到单分散性微球. 相似文献
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Abstract Seed dispersion polymerization of methyl methacrylate (MMA) in the presence of monodisperse PMMA particles was carried out in an aqueous methanol using poly(methacrylic acid) stabilizer. The polymerization using 2. 5 μ. m-sized seed particles gave monodisperse PMMA particles in the diameter up to 4. 9 μm. The solvent composition and monomer concentration greatly affected the polymerization behavior. Under appropriate conditions, monodisperse PMMA particles in the diameter up to 8. 9 μ, m was prepared from 4. 6 μm-sized seed particles. The seed dispersion polymerization of styrene in the presence of the seed particles produced monodisperse PMMA-polystyrene particles in the micron range. The particles were supposed to have a structure consisting of PMMA-core and polystyrene-shell from ESCA analysis. 相似文献
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Ya Yan 《Journal of Dispersion Science and Technology》2013,34(4):575-580
Polystyrene (PS) colloidal particles were prepared in aqueous solution by a quick emulsifier-free emulsion polymerization (EFEP) method. The scanning electron microscopy (SEM) images indicate that the as-synthesized particles have good sphericity and uniform size (dispersion coefficient Cv is less than 5%). The monodisperse PS microspheres with different diameter were obtained easily by varying the monomer concentration. The atomic force microscopy (AFM) images show that the PS microspheres were self-assembled into three-dimensional ordered structure on micas by dropping-casting method. The self-assembly method is simple and quick. Based on the experimental results, a possible self-assembly mechanism was proposed. 相似文献
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N. N. Shevchenko T. G. Evseeva D. I. Shevaldysheva B. M. Shabsel’s Yu. O. Skurkis A. Yu. Men’shikova 《Russian Journal of Applied Chemistry》2013,86(2):242-252
Crosslinked monodisperse microspheres of a diameter 3–10 μm were synthesized by a method of heterophase copolymerization of ethylene glycol dimethacrylate or styrene with divinylbenzene and methacrylic acid on seed nuclei produced by dispersion polymerization of styrene. The diameter and distribution of the microspheres by size, their morphology and surface structure were analyzed by SEM. Factors that control these characteristics of the microspheres in the polymerization process were determined. Swelling ability of the microspheres in toluene and dimethylformamide was evaluated using optical microscopy. 相似文献
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Synthesis of monodisperse polystyrene microspheres by dispersion polymerization using sodium polyaspartate 总被引:1,自引:0,他引:1
We prepared monodisperse polystyrene microspheres by dispersion polymerization using sodium polyaspartate (PAspNa) as a dispersion
stabilizer in an ethanol/water medium. The influence of reaction parameters, i.e., the volume fraction of ethanol in the medium,
stabilizer concentration, and the monomer concentration, on the average diameter of the prepared polystyrene microspheres
and its distribution were investigated. Polystyrene microspheres were successfully prepared, and the average diameter of the
prepared monodisperse polystyrene microspheres was controlled by adjusting the reaction parameters. The zeta potential of
the microspheres and the time course of conversion, the particle diameter and its distribution, and particle numbers were
also examined. It was found that PAspNa as a dispersion stabilizer provides an environmentally benign process for the preparation
of monodisperse polymer microspheres by dispersion polymerization. 相似文献
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K. J. O'Callaghan A. J. Paine A. Rudin 《Journal of polymer science. Part A, Polymer chemistry》1995,33(11):1849-1857
The emulsion polymerization of large MMA/BA copolymer particles with narrow particle size distributions and core-shell structure is described. A series of sequential seeded growth emulsion polymerizations were used to obtain monodisperse particles with diameters of at least 3 μm, at 30% solids contents. Because the core and shell polymers used here were chemically similar, core-shell structures could not be verified by differential staining tech-niques. Core-shell structure was demonstrated by minimum film-forming temperature studies and by scanning electron microscopy in conjunction with energy dispersive x-ray analysis, using chlorine-labeled core polymers. © 1995 John Wiley & Sons, Inc. 相似文献
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PDMAAm microspheres have been obtained by inverse suspension, inverse emulsion, and dispersion polymerization. Conventional inverse suspension polymerization in toluene/trichloroethene is modified by the use of ultrasound. The resulting hydrogel microspheres are examined by dynamic light scattering and scanning electron microscopy to afford the morphology, dispersity, and size of the microspheres. Inverse suspension polymerization yields 100‐µm particles, while those obtained by inverse emulsion polymerization are 0.13–1 µm in diameter. While the inverse techniques produce particles of broad size distribution, monodisperse microspheres are obtained by the Kraton G 1650‐stabilized dispersion polymerization of DMAAm in a toluene/heptane medium. The particle size and polydispersity could be controlled by the addition of water into the dispersed phase, and by varying the cellulose acetate butyrate or Kraton G 1650 concentration and the toluene/trichloroethene or toluene/heptane ratio.