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金属—卟啉络合体系引发的活性聚合及不死聚合 总被引:1,自引:1,他引:1
金属-卟啉络合物是一类可以引发环氧化物、环硫化物、内酯、丙烯酸酯及α-甲基丙烯酸酯等进行活性聚合或不死聚合的新型引发剂。本文概述了上述两种聚合反应的机理、特点、在高分子合成中的应用及其与其他活性聚合的区别。 相似文献
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波聚合是一种通过局部反应区域向未反应区域连续移动将单体转化为聚合物的反应模式,具有简便快速、节能降耗和产物性能优异等优势,是化学合成、功能材料与结构材料制备的新方法。本文对波聚合反应体系、引发、过程、应用及存在问题等方面进行综述。重点评述了新型波聚合体系如二元或多元体系、离子液体体系、深共晶溶剂体系等;新型引发剂如光引发剂和离子液体引发剂等特殊引发剂;波聚合反应体系中的助剂如填料、交联剂、链转移剂、活化剂、增稠剂、表面活性剂和催化剂等对聚合过程和产物结构性能的影响;新发展的引发方式如紫外线、水、等离子体和耦合引发等;以及特殊波聚合过程。最后,展望了波聚合存在问题和商业化应用的研究方向。 相似文献
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在UV光照射下, 以Irgacure 1103/TEMPO为引发剂, 实现了苯乙烯的低温光引发可控聚合, 得到了低分散性的聚苯乙烯. 与热引发聚合相比较, 光聚合的反应条件更温和, 聚合速率更快. 探讨了聚合体系中光引发剂及光强等因素的影响, 实现了光聚合产物的扩链反应. 相似文献
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介绍了稳定自由基聚合的反应原理、引发剂设计,以及用稳定自由基聚合制备嵌段共聚物的几种方法:连续加料法、双官能团引发剂法和一步法。对于光引发聚合的原理及硫自由基的稳定性对聚合反应的影响也进行了讨论。 相似文献
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原子转移自由基聚合(ATRP)作为一种有效的"活性"/可控聚合可对聚合物进行分子设计,制备结构和相对分子质量可控的各类聚合物,具有潜在而广泛的研究价值。本文综述了ATRP的研究进展,特别是对传统ATRP催化引发体系、RATRP催化引发体系、AGET ATRP催化引发体系、SR&NI ATRP催化引发体系、ICAR ATRP催化引发体系、ARGET ATRP催化引发体系、杂化或双金属催化体系等的催化引发机理进行了详细的介绍。并综述了ATRP聚合中各种实施方法如本体聚合法、溶液聚合法、悬浮聚合法、乳液聚合法等的研究现状。 相似文献
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等离子体引发聚合的机理初探 总被引:5,自引:0,他引:5
等离子体引发聚合与常规自由基聚合存在许多不同之处。本文从等离子体引发聚合物一些现象,如较强的溶剂效应、极高的单体选择性、主成超高分子量聚合物等方面,系统介绍了等离子体引发聚合的机理研究成果,并提出了自己的看法。 相似文献
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自由基聚合是高分子化学课程中的重要一章,自由基聚合动力学(包括聚合速率、平均相对分子质量及分布)是教学中的重要内容。本文讨论了建立自由基聚合微观动力学模型的基础:三个基本假设和四个简化条件,阐释了传统单官能度引发剂引发的聚合体系速率方程推导中这些假设和条件的运用,并扩展到双官能度引发剂体系,得到基元反应速率和总速率。提出从三个层次讨论影响自由基聚合速率的因素,深化了对自由基聚合速率教和学。 相似文献
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聚吡咯的合成与新型双离子电池性能研究 总被引:10,自引:0,他引:10
用反相微乳聚合法制备了十二苯磺酸(DBSA)掺杂的导电聚吡咯纳米材料, DBSA既作为表面活性剂又作为掺杂剂, 能够提高聚吡咯的导电性. 用制备出的DBSA-PPy 为正极材料, 石墨为负极材料组装双离子电池, 测试结果表明, C/DBSA-PPy 电池的电化学性能已达到传统锂离子电池的水平, 这是因其具有较高的导电性和特殊掺杂结构的聚吡咯使其电化学性能得到优化. 相似文献
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《Electroanalysis》2006,18(2):131-140
Reduction of carbonyl group in aldehydes and ketones, as well as oxidation of numerous aldehydes is discussed, as well as those reductions of organic compounds where the C?O group activates cleavage of an adjacent C? X bond where X is a good leaving group like halogen, OH, NH2 or SR or activates hydrogenation of an adjacent C?C group. Survey involves aliphatic and aromatic aldehydes, aryl alkyl and diaryl ketones, as well as α‐ketoacids, 1,2‐diketones and compounds where the carbonyl group is a part of a ring. The role of acid–base, hydration–dehydration and in some cases keto–enol equilibria on electrochemical behavior is pointed out, as well as the role of buffer kind and concentration and the nature of the cation of supporting electrolyte. Better understanding of these factors promises finding of best conditions for electroanalytical procedures. 相似文献
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New X-ray methods have been developed for the determination of as little as 1 μg of fluorine or as little as 0.1 μg of sulfur. Fluorine as fluoride is precipitated as lanthanum fluoride in 75% ethanol-water mixture and determined by measuring the amount of lanthanum present in the precipitate. Sulfur as sulfate is precipitated as barium sulfate from a barium sulfate saturated 50% ethanol-buffer mixture, using selenate as a coprecipitant, and determined by measuring the amount of sulfur present. Sulfur as sulfide is precipitated as cadmium sulfide and determined by measuring the amount of sulfur or cadmium in the precipitate. 相似文献
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醋酸和丙三醇对制备SrTiO3的影响 总被引:5,自引:0,他引:5
醋酸和丙三醇对制备SrTiO_3的影响颜秀茹,霍明亮,王建萍,王菲,曾淑兰(天津大学化学系天津300072)关键词 冰醋酸,溶胶-凝胶过程,丙三醇,SrTiO_3SrTiO3是电子材料中使用最广的材料之一,有关它的制备已有不少报道。一般可以通过SrCO... 相似文献
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WU Ren-Ping YU Yan GU Ying Yun GUO Jin-Yu 《结构化学》2007,26(5):562-566
Deep color glass-ceramics is prepared by using gold tailings as the main raw material, and Cr2O3 is added as nucleation agent. Influence of different Cr2O3 additions on crystallization structure and properties of CaO-MgO-Al2O3-SiO2 glass-ceramics has been discussed so as to select optimum additions. DTA is employed to determine optimum crystallization and nucleation temperatures; XRD and SEM are used to characterize microstructure of each sample; and performance indexes, such as water absorption, bulk density, flexural strength and so on, are also determined. Experimental results show that when 3wt% Cr2O3 is introduced, fine glass-ceramics with diopside as the main crystal and Ca-Fe diopside as the second-crystal is obtained, and its corresponding performance indexes are as follows: water absorption 0.12%, bulk density 2.56 g/cm3, and flexural strength 70.01 Mpa. 相似文献
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An experimental technique based on a modified vibrating orifice aerosol generator has been employed to study unsteady evaporation of linear streams of highly monodisperse binary microdroplets of volatile constituents over short time periods (i.e., <1 ms), such that the droplet composition remains nearly constant. The droplet size and temperature (i.e., refractive index) have been determined with high temporal resolution from the resonances observed in the simultaneous elastic and Raman light scattering spectra obtained by varying the droplet size through modulation of droplet generation frequency. By using this technique we show that thermodynamic parameters of binary systems, such as activity coefficients as well as vapor pressures of the constituents as functions of temperature, can be determined. We have applied the procedure to study unsteady evaporation rates of pure ethanol and methanol droplets as well as binary droplets containing various ratios of ethanol and methanol. We have obtained vapor pressures of ethanol and methanol as functions of temperature as well as activity coefficients of ethanol and methanol as functions of composition, and the results show excellent agreements with the values reported in the literature. The technique presented in this paper is applicable to any binary system containing at least one volatile constituent. Copyright 2000 Academic Press. 相似文献