超支化聚合物的研究进展

超支化聚合物作为一种高度支化的聚合物,由于其独特的结构和性能而成为研究热点之一.本文将主要介绍超支化聚合物的结构、性质、合成方法以及应用前景.     

间歇式乳液聚合法制备超支化聚丙烯酸丁酯

以丙烯酸丁酯为单体,二乙烯基苯为支化剂,十二硫醇为链转移剂,通过间歇式乳液聚合法成功制备了一系列高转化率的聚丙烯酸丁酯超支化聚合物。通过核磁共振对其结构进行了表征,同时还对聚合物乳液粒径及其分布,超支化聚合物的溶解性、支化度、相对分子质量及相对分子质量分布进行了研究。结果表明:超支化聚合物分子结构中含有丙烯酸丁酯、二乙烯基苯和十二硫醇;聚合物乳液粒径较小,粒径分布较窄;超支化聚合物在有机溶剂中具有良好的溶解性;随着支化剂用量的增加,聚合物支化度增加,相对分子质量降低,相对分子质量分布变窄;随着链转移剂用量的增加,聚合物支化度增加,相对分子质量分布变窄。     

支化结构对树枝状聚合物溶液剪切前后流变性能的影响

采用吴茵混调器模拟聚合物在其配制、输送、注入中的机械剪切作用,研究了不同支化程度对剪切前后的驱油用树枝状聚合物溶液的流变性能的影响。首先制备了3种不同支化程度的树枝状聚合物,研究了剪切前后的树枝状聚合物的分子链粒径分布和分子量大小,然后研究了不同因素对树枝状聚合物流变性能的影响并考察了树枝状聚合物溶液的黏弹性能,最后结合环境扫描电镜分析支化结构对剪切前后树枝状聚合物溶液的流变性能的影响。结果表明：支化程度高的树枝状聚合物具有更大的流体力学半径和分子量,受环境影响较小;树枝状聚合物溶液呈现假塑性流体特征,支化程度越高,剪切前后的聚合物溶液幂律指数n越小、稠度系数K越大;支化程度高的树枝状聚合物溶液支链间越容易发生缠结,形成致密、多层的空间网状结构,致使剪切前后的聚合物溶液的流变性能越好。     

超支化聚合物合成的研究进展

超支化聚合物是一类高度支化的三维大分子,由于其独特的结构和性质以及潜在的应用,已经在高分子材料领域得到快速发展。综述了超支化聚合物合成方法的研究进展,其中主要介绍单单体法(SMM)、双单体法(DMM)、偶合单体法(CMM)以及点击化学法,同时对超支化聚合物的发展前景进行了分析和展望。     

支化结构对树枝状聚合物静态吸附特征的影响

采用浸泡法研究了不同支化程度的驱油用树枝状聚合物在石英砂上的静态吸附特征,并利用动静态激光光散射仪和环境扫描电子显微镜测定了聚合物溶液的分子尺寸和微观结构。结果表明,不同支化程度的树枝状聚合物溶液的等温吸附曲线均呈现三段式的吸附特点;在初始阶段,支化结构小的聚合物支链条数较少以及流体力学半径较小,其在固定表面积的石英砂上吸附位阻比支化结构大的聚合物小,导致吸附量较大;在吸附形式为多层吸附的Ⅱ、Ⅲ阶段,支化程度大的聚合物支化链间相互作用越强,易缠结形成网络结构,致使其在石英砂表面吸附层数多,吸附量比支化程度小的聚合物多。     

支化聚合物的合成及表征

支化聚合物由于其独特的结构和性能以及可实现规模化生产的特点,已迅速成为一类重要的和具有广阔应用潜力的高分子材料。本文综述了近年来制备支化聚合物常用的合成方法：主链引发法、主链-支链偶联法以及单体-大分子单体共聚法;介绍了表征支化聚合物支化度的方法：红外光谱法、核磁共振法、差热分析法、GPC和自动粘度计联用法,并评价了各种方法的优缺点,目的在于加深人们对该领域的了解,从而促进该领域的快速发展。     

高度支化聚有机硅烷的研究进展（Ⅰ）

总结了近几年来高度支化聚有机硅烷的研究进展,重点综述了含硅树枝状聚合物及超支化聚合物的合成和应用研究,并简要介绍了该类聚合物的表征分析手段。     

高度支化聚有机硅烷的研究进展（Ⅱ）

3超支化聚合物的结构与合成早在1952年,Flory[20]就第一次提出了“高度支化聚合物”(H ighly branched polym ers)的概念,并从理论研究的角度预测到由ABx(x≥2)型单体缩聚可得到高度支化聚合物而不会凝胶。但直到20世纪80年代末期Dupont公司的研究者Kim和W ebster犤21犦首次用A     

超支化聚合物共价修饰碳纳米管的制备及应用研究

碳纳米管(CNTs)具有很多优良性能,但由于在聚合物基体分散性差,限制了其广泛应用。超支化聚合物是高度支化的大分子,具有低黏度、高溶解性及含有大量末端基团等特点。利用超支化聚合物共价修饰CNTs,不仅可以提高CNTs在聚合物基体中的分散性,还能使CNTs拥有新的功能。介绍了超支化聚合物共价修饰CNTs的方法,探讨了其在生物医学、纳米材料等方面的应用前景,最后对超支化聚合物共价修饰CNTs的发展提出了建议。     

国内文献摘要

正一种两嵌段聚乙烯基超支化聚合物及其制备方法和应用本发明涉及高度支化聚合物的制备技术领域,具体涉及一种两嵌段聚乙烯基超支化聚合物及其制备方法和应用,其制备方法,包括两个步骤:一、制备末端羟基聚乙烯共聚物;二、制备两嵌段聚乙烯基超支化聚合物。本发明设计合成聚乙烯-超支化嵌段聚合物,一段为线性聚乙烯链,另一段为超支化聚合     

Hyperbranched organoboron polymer electrolytes derived from glycerol

Solid polymer electrolytes are still collecting attention today for development of safer Li-ion batteries. Introduction of boron moieties to electrolytes generally improves ion conductive properties of resultant electrolytes. Herein, we have undertaken dehydrocoupling reaction between glycerol (Gly)/triethylene glycol (TEG) and hydroborane to synthesize highly branched organoboron polymer electrolytes. Increase in amorphous nature of polymer due to branched structure improved the ionic conduction. This was supported from decreased Vogel–Fulcher–Tammann parameters corresponding to activation energy of ion transport in matrices. When Gly content was increased beyond [Gly]/[TEG] = 15%, ionic conductivity decreased due to decrease in solubility of the salt in organoboron polymer matrix.     

Concept of secondary heterogeneous structure of long-chain branched polyethylene

The mechanism of formation of surface roughness and extrusion swelling of the extrudate and the steady-shear viscous flow behavior in the region of high shear rate for branched polymers were investigated using two low-density polyethylenes and their sheared samples. These two polyethylenes varied in their degree of branching, molecular weight, and molecular weight distribution but were similar in their melt flow index. The effect of molecular parameters, especially long-chain branching, on viscoelastic properties in the molten state was also considered. Samples of various degree of shearing level were prepared by passing them repeatedly through an extruder. Results of intrinsic viscometry, gel permeation chromatography, and infrared spectroscopy of the original and the sheared samples indicate that no appreciable variation between them takes place in the molecular parameters during the process of extrusion shearing. Both surface roughness and extrusion swelling of the extrudate diminish with increase in the extent of shear. The extrusion shearing affects the surface roughness and extrusion swelling of the extrudate as well as the capillary entrance effect more markedly for the highly branched polymers with considerably higher molecular weight than for the less branched species with bell-type molecular weight distribution. These results demonstrate that heterogeneity becomes more conspicuous with the degree of long-chain branching level, and therefore the role of long-chain branching in the development of the heterogeneity is particularly important. It is suggested that the secondary heterogeneous structure arises through phase separation or from the heterogeneous formation of strongly entangled network at the branching point of the long-chain branching in the manufacturing process of the low-density polyethylene and that its presence causes the distinctive viscoelastic properties of long-chain branched polymer melts.     

Preparation and properties of benzophenone chromophoric group branched polymer for self‐decontamination

To prepare self‐decontamination materials with highly reactive chemical species, such as radicals, the benzophenone chromophoric group branched polymer was synthesized by Friedel–Crafts acylation of polystyrene with benzoyl chloride. The resultant polymer could be prepared into a casting film, and the polymer solution and film were characterized by FTIR, NMR, UV–VIS, XRD, and DSC. From the analyses, it was verified that the benzophenone chromophoric group branched polymer was successfully prepared, and the resultant polymer revealed radical reactivities such as antibacterial effect and decoloration of dye, under UV irradiation. POLYM. ENG. SCI., 47:1750–1755, 2007. © 2007 Society of Plastics Engineers     

Effects of charge density and structure of side-chain branching on the composition of polyanion-polycation complexes

A combination of methods (turbidimetry and conductometry) was used to study polyanion-polycation complex formation and its stoichiometry. The influence of charge density on the polyelectrolyte complex (PEC) formation and the behaviour of PEC upon addition of salt (sodium chloride) was studied; the specific structure of the individual components was also investigated. As anionic polymer components modified poly(ethylene oxide) ionomers and poly(acrylamide-co-acrylic acid) of various charge densities were used. For the cationic polymer component, cationically modified polyacrylamides, poly(dimethyldiallylammonium chloride) and highly branched poly(ethylenimine) were used. By a variation of chemical structure of the individual polymers and their charge densities, the stoichiometry of the PEC formation could be very strongly influenced, as shown by turbidimetric and conductometric endpoint measurements; a 1:1 stoichiometry is the exception. In contrast to polyacrylamides with various amounts of carboxylate groups (polyacrylate copolymers), carboxylate-containing ethylene oxide comonomers, because of their highly branched structure, have a strong tendency towards immediate gel formation.     

超支化聚合物及其自组装研究进展

介绍了超支化聚合物的结构性质特点及合成方法,主要有缩聚反应、乙烯基自缩合反应(SCVP)、开环聚合等;概述了超支化聚合物的自组装及其应用研究情况,如在生物医药、修饰碳纳米管及其它领域的实际应用现状。     

聚烯烃热塑性弹性体POE官能化及其应用

聚烯烃热塑性弹性体（POE）的非极性限制了它的进一步应用,为了扩大其使用领域,对POE官能化引起关注。将POE作为接枝机体树脂,利用其支化度比较高、容易形成接枝点来获得较高的接枝率;由于其侧链相对较大,有可能降低大分子自由基之间碰撞的几率,从而减轻凝胶化程度,得到具有良好流动性的接枝树脂。本文综述了聚烯烃热塑性弹性体POE官能化几种方法,包括在有机过氧化物引发剂存在下的熔融接枝法、裂解引发接枝、机械力引发接枝、复合引发接枝等等,并对其产物的应用进行概括。     

Evaluation of different branching functions used in the determination of random branching by GPC

Three branching functions are evaluated for use in the measurement of random branching by GPC. Initial evaluations of the functions g^1/2, g^3/2, and h³ were made by computer simulations of GPC experiments using published data of lightly and highly randomly branched polymers. Actual GPC experiments were then performed on characterized samples of lightly and highly branched styrene–divinylbenzene copolymers. The results indicate that h³ adequately predicts branching and molecular weight at all branching densities, whileg^1/2 is accurate only for lightly branched polymers and g^3/2 is accurate only for highly branched polymers. A means for predicting the M–[η] curve for branched polymers from the M–[η] calibration curve for linear polymer is proposed.     

聚酰亚胺增韧改性研究进展

综述了国内外近几年对聚酰亚胺(PI)增韧的研究进展,对超支化增韧、柔性基团增韧、二胺二酐增韧及结构改性进行了概述。超支化分子具有高度支化的三维立体结构和更多的端基,可降低分子链的纠缠;柔性基团可提高分子链的柔顺性,两者均可提高材料的韧性;设计合成新型二胺二酐可用于改善PI的韧性;破坏原来分子链的结构,可降低分子链与苯环间的共轭,提高PI的韧性;对今后的研究方向和趋势进行了展望：分别将超支化与柔性基团和二胺二酐结合,协同增韧PI。     

GC/MS and PGC/MS analyses of plasma polymerization for benzaldehyde

Gas chromatography/mass spectrometry studies of gas condensates in plasma and pyrolysis products of plasma polymer for benzaldehyde were made. Both products' analyses indicate the significant presence of benzyl and carbonyl groups in plasma polymer samples. Infrared measurements were also used to correlate the structures suggested by GC/MS results. A radical mechanism, which involved hydrogen abstraction, aldehyde group abstraction, and benzyl fragmentation under plasma activation, was proposed. The highly crosslinked and branched structures of the plasma polymer were attributed to the subsequent reactivity of free radicals, formed as a result of the scission of the chemical bonds in the benzaldehyde molecules.