稀土络合催化环硫丙烷开环聚合

本文首次研究了稀土络合催化环硫丙烷开环聚合。发现稀土元素膦酸盐、环烷酸盐及乙酰丙酮盐与三异丁基铝或三乙基铝、水组成的络合催化剂是环硫丙烷开环聚合的优良催化剂,在甲苯中呈均相聚合、活性大,聚合物分子量高(几百万)。聚合反应速度对单体浓度、催化剂浓度分别呈一级关系,聚合活化能为61.4kJ/mol。并用~(13)C-NMR谱,X-ray衍射,GPC,DSC等研究了稀土聚环硫丙烷链结构。     

杯[6]芳烃钪配合物催化DTC开环聚合动力学及其机理

以对叔丁基杯[6]芳烃和异丙氧基钪为原料, 合成了对叔丁基杯[6]芳烃钪配合物, 该配合物可在温和条件下单组分引发2,2－二甲基三亚甲基环碳酸酯(DTC)开环聚合, 制备重均分子量为33700, 分子量分布为1.21的聚合产物. 动力学研究表明该聚合反应对单体和催化剂浓度均呈一次方关系, 表观活化能为22.7 kJ/mol; 通过1H NMR研究聚合物端基, 表明单体的开环机理为Sc-O活性中心引发的酰氧键断裂开环.     

以可溶性催化剂一氯二乙基铝-氯化钴吡啶聚合丁二烯时有关分子量的一些规律

1.研究了聚合时起始单体浓度、催化剂组分浓度以及聚合温度对产物分子量的影响,找到聚合度的倒数分别与起始单体浓度的倒数、氯化钴浓度的平方根、一氯二乙基铝浓度 的平方根呈直线关系。根据聚合温度与产物聚合度的关系,求得总的链终止活化能约在14千卡/克分子左右。 2.研究了聚合时几种给电子化合物及庚烷的加入对产物分子量的影响。发现聚合度的倒数与给电子化合物的浓度或庚烷浓度成直线关系,设直线斜率为链转移系数,则对三乙胺、四氢呋喃、吡啶、乙硫醚、庚烷分别为1.87,0.36,0.19,0.14,0.0012。     

稀土络合催化炔烃和开环聚合新进展

本文综述了我国首创开拓的稀土络台催化聚合在炔烃和开环聚合方面的新进展.用稀土络合催化剂可以使乙炔、苯乙块在室温下聚合制备高顺式含量和抗氧化稳定性良好的聚炔烃膜;可以使环氧乙烷、环氧丙烷、环氧氯丙烷和环硫丙烷聚合制备高分子量聚合物;可以使丙交酯聚合制备可控分子量聚合物.     

二茚基稀土胺化物催化丙烯腈聚合

用二茚基稀土胺化物Ind2LnN(i-Pr)2(Ln=Y,Yb)作为单组分催化剂催化丙烯腈聚合,研究了催化剂用量、单体浓度及聚合温度对标题化合物的催化活性和所得聚丙烯腈的分子量的影响。提高聚合发应温度可明显提高催化活性,当聚合温度达50℃,单体浓度为5.1mol     

聚DL-乳酸的合成及其热性能研究

以辛酸亚锡为催化剂催化丙交酯开环聚合DL-乳酸(PDLLA)。研究了影响PDLLA分子量的因素包括丙交酯单体的纯度、催化剂的浓度、反应温度、反应时间及真空度等。用DSC,TGA分析了不同分子量PDLLA的警警化转变和热失重。结果表明,PDLLA是热不稳定聚合物,残留的单体、催化剂及低聚物是影响PDLLA热稳定性的因素,除去其中残留的单体、催化剂及低聚物可以提高PDLLA的热稳定性。     

甲基丙烯酸长链烷基酯的基团转移聚合研究

进行了甲基丙烯酸长链烷基酯（庚、辛、壬酯的混合物）的基团转移聚合．得到了具有较高分子量和转化率．分子量分布较窄的聚合产物．研究了聚合条件对产物的分子量及分布，转化率，聚合速率的影响．探讨了聚合反应动力学．认为聚合体系的非极性不利于催化剂的离解，单体较大的空间障碍使扩散困难．均是表观活化能升高和转化难以完全的原因．发现此类单体的基团转移聚合对温度的依赖性极大，本体聚合无自加速现象，容易得到较高的分子量．     

用双官能团引发剂进行的基团转移嵌段共聚研究

本文用二种双官能团引发剂进行基团转移嵌段共聚研究,得到了一系列实测分子量和理论分子量相近、分子量分布较窄的A-B-A型嵌段共聚物。用GPC、~1H-NMR、DSC等手段对嵌段共聚物进行了表征,证明确是两相嵌段共聚丙烯酸酯。发现位阻较大的单体作为第二单体时不利于聚合。过高的催化剂用量使嵌段共聚的总转化率降低。使用极性较大的溶剂可缩短第一步聚合的诱导期,但不影响第二步聚合的诱导期,即极性较大的溶剂有利于催化剂的离解。单体浓度增大使共聚物的分子量减小,多分散性指数增大。可通过单体投料比改变共聚物的热形变温度。     

甲基丙烯酸甲酯的原子转移自由基悬浮聚合

以 1 苯基氯乙烷为引发剂 ,氯化亚铜为催化剂 ,2 ,2 联吡啶为配体 ,外加搅拌 ,氮气保护下进行了甲基丙烯酸甲酯 (MMA)在 80℃下的原子转移悬浮聚合 .结果表明 ,聚合反应符合对单体浓度为一级的动力学关系 .经计算聚合体系的增长自由基浓度为 5 .74× 10 - 8mol L .聚合物分子量随转化率呈线性增加 ,分子量分布较窄 ,Mw Mn 在 1.37～ 1.40之间 .还以AIBN为引发剂 ,在三氯化铁和三苯基膦存在下进行了MMA的反向原子转移本体和悬浮聚合研究 .结果证明本体聚合具有好的可控特征 ,分子量随转化率呈线性增长 ,分子量分布指数在 1.2 7～ 1.31之间 .聚合反应速率较快 ,聚合体系中的增长自由基浓度较高 ,为 1.6 4× 10 - 7mol L .而在此催化体系下的悬浮聚合则完全失去了活性特征     

环硅氧烷负离子乳液聚合中活性中心浓度的变化规律

以八甲基环四硅氧烷(D4)为单体,十二烷基二甲基苄基氢氧化铵(BDAH)为乳化剂兼催化剂,进行环硅氧烷负离子乳液聚合,采用凝胶色谱(GPC)测定聚合产物的转化率及分子量.在此基础上,分析基元反应,提出活性中心生成机理,并应用环硅氧烷开环聚合普适动力学模型计算乳液聚合平衡之前的活性中心浓度变化规律.结果发现,聚合温度较低时,活性中心浓度随时间逐渐增加,最终恒定;聚合温度较高时,活性中心浓度随时间仅单调递增.结果与机理相符.     

RING-OPENING POLYMERIZATION OF PROPYLENE SULFIDE CATALYZED BY BIMETALLIC OXO ALKOXIDE

It was shown that the polymerization rate of propylene sulfide is second order with respect tomonomer concentration and half order with respect to catalyst concentration. A mechanism ofbimolecular coordinated propagation of propylene sulfide and association of the catalyst in thepolymerization system were proposed. The activation energy of polymerization was measured as12.2±0. 5 kcal/mole. Chain transfer constants of monomer and solvent were calculated. Thechange of molecular weight and molecular weight distribution with conversion was followed by GPCwhich was improved by adding LiCl to eluant.     

RING OPENING POLYMERIZATION OF PROPYLENE SULFIDE BY RARE EARTH COORDINATION CATALYSTS*

Ring opening polymerization of propylene sulfide using rare earth coordination catalysts has been investigated for the first time. It has been found that trinary rare earth coordination catslysts composed of rare earth compounds of phosphonate, naphthenate or acetylacetonate, trialkyl sluminum and water are effective catalysts for the polymerization of propylene sulfide. The polymerization in toluene is a homogeneous reaction. High molecular weight as high as several million poly(propylene sulfide) with high yield can be prepared by these catalysts. Kinetic studies showed that the polymerization rate is of first order with respect to both monomer concentration and catalyst concentration. The activation energy of the polymerization reaction is 61.4 k fJ/mol. The structure of the polymers so obtained has also been characterized by ~(13)C NMR spectroscopy, X-ray diffraction, gel permeation chromatography and differential scanning calorimetry.     

有机氨钙催化聚合脂肪族环酯

分别用经环氧丙烷和环氧丙烷/乙腈处理的氨钙催化剂催化聚合了ε-己内酯和L-丙交酯.研究了催化剂浓度、聚合时间、真空度、聚合温度和陈化温度等对聚合收率和聚合物粘均分子量的影响.结果表明,有机氨钙催化剂对ε-己内酯和L-丙交酯的开环聚合有较高的催化活性,在较低的温度下和较短的时间内,即可获得较高的转化率和较高的分子量,而且具有一些“准活性聚合”的特点,分子量在一定范围内可控.陈化处理和乙腈的加入可以大大提高聚ε-己内酯的分子量,最大分子量达到27×10⁴.     

Ring opening polymerization of propylene oxide by chitosan-supported rare earth catalytic system and its kinetics

Ring opening polymerization of propylene oxide in the presence of a new type of catalytic system composed of chitosan-supported rare earth complex, triisobutyl aluminium, and acetylacetone and its kinetics have been studied for the first time. It has been found that the characteristics of this catalytic system are of high catalytic activity, of higher stereoselectivity, and of a high molecular weight polymer of 2 × 10⁶. Kinetic studies show that the polymerization rate is first order with respect to monomer concentration and catalyst concentration, respectively. The apparent activation energy of the polymerization reaction is 37.1 kJ/mol. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2177–2182, 1997     

合成高分子量无规聚丙烯—在烷烃溶剂中聚合及性能初步表征

丙烯聚合;茂金属催化剂;立体结构;合成高分子量无规聚丙烯—在烷烃溶剂中聚合及性能初步表征     

H_2O/TiCl_4/Py体系引发苯乙烯正离子聚合

研究了在少量吡啶(Py)存在下由水(H2O)四氯化钛(TiCl4)体系引发苯乙烯于二氯甲烷正己烷中进行碳正离子聚合,分别考察[Py]、[H2O]和[TiCl4]对聚合速率、产物分子量与分子量分布的影响.实验结果表明,少量亲核试剂吡啶(Py)对聚合反应起着重要作用,可有效地降低聚合速率和使分子量分布变窄;随着[H2O]和[Py]降低或[TiCl4]增加,聚合产物的分子量增加,而分子量分布指数(Mw Mn)基本维持在1.8左右;随着[Py]增加,聚合速率降低;随着[H2O]和[TiCl4]增加,聚合速率提高.聚合速率对单体浓度呈一级动力学关系,对Py、H2O和TiCl4的反应级数分别为-0.72、0.72和1.86.聚合速率对TiCl4浓度呈接近二级动力学关系,这可能与体系中TiCl4主要以二聚体形式存在有关.聚合转化率和产物分子量均随着反应时间延长而逐渐增大,PS的数均分子量与转化率呈线性增加关系.     

Anionic graft polymerization of propylene sulfide on cellulose. I

The anionic graft polymerization of propylene sulfide on cellulose membrane was studied. Alkali cellulosates were used to initiate graft polymerization, and graft polymers of high polypropylene sulfide content were obtained in good yields. The graft polymerization was accompanied by a certain extent of homopolymerization. The effects of reaction solvent, monomer concentration, cellulosate degree of substitution, and type of the alkali metal cellulosate on the graft polymer composition, yield, and on the molecular weight of the grafted side chains were investigated.     

Reaction of Lithium Cellulosate with Episulfides

The reactions of propylene, ethylene, and styrene sulfide with cotton fabrics in the form of their lithium cellulosate derivative, obtained by metallation with lithium methoxide, were studied. Both graft and homo-polymerization took place and in the reaction with propylene and ethylene sulfide, cotton fabrics with high polysulfide content were obtained. With propylene sulfide 50% of the monomer polymerized was grafted. The effects of monomer concentration, cellulosate degree of substitution, reaction time, and solvent on the polymerization were investigated. In contrast with propylene and ethylene sulfide, only small conversions were obtained in the reaction with styrene sulfide. The results were attributed to steric effects.     

合成高分子量无规聚丙烯的研究 Ⅰ.单茂基钛化合物/MAO催化丙烯聚合

用合成得到的五甲基环戊二烯基三苄氧基钛［ＣｐＴｉ（ＯＢｚ）３］与甲基铝氧烷（ＭＡＯ）组成新型催化体系进行丙烯的均聚合,研究了影响聚合活性及产物分子量的各种因素．结果表明,用甲基取代钛化合物茂环上的氢可使聚合产物分子量增大一个数量级,所制得的聚丙烯为无规聚丙烯,具有高分子量（Ｍｗ＝２０～１００×１０４）．     

Use of block copolymer surfactants in the inverse-suspension polymerization of acrylamide

A comprehensive experimental investigation of the inverse microsuspension polymerization of acrylamide using an oil-soluble initiator and a block copolymeric surfactant whose hydrophobic miety is poly(12-hydroxystearic acid) and whose hydrophilic moeity is polyethylene oxide was carried out. It was found that the initial polymerization rate was first order with respect to molar monomer concentration, first order with respect to molar initiator concentration and zeroth order with respect to molar emulsifier concentration. Based on these experimental findings, a mechanism was proposed which includes initiation, propagation transfer to monomer and termination. It also includes transfer to impurities which are believed to be found in the surfactant. The kinetic model developed from the proposed mechanism is found to be in good agreement with the experimental conversion and weight-average molecular weight data. Comparing with sorbitan esters of fatty acids, the copolymeric surfactant provides higher polymerization rate and very high and linear molecular weight comparable to those obtained by solution polymerization.