杂多酸引发四氢呋喃聚合反应 Ⅲ.环氧乙烷对聚合反应的影响

最近我们研究发现环氧乙烷（ＥＯ）可有效地促进低腐蚀性磷钨杂多酸（ＰＷ１２）引发的四氢呋喃（ＴＨＦ）聚合反应,产物分子量可通过体系中水或低分子二醇的含量进行控制［１,２］．而在没有ＥＯ存在时,相似条件下ＰＷ１２引发ＴＨＦ聚合反应２４ｈ,没有检出聚合物［...     

杂多酸引发四氢呋喃聚合反应 Ⅱ.水的反应行为

前报我们对低腐蚀性非均相的磷钨杂多酸Ｈ３ＰＷ１２Ｏ４０（ＰＷ１２）引发体系进行了研究［１］,发现环氧乙烷（ＥＯ）可有效地促进ＰＷ１２引发的四氢呋喃（ＴＨＦ）聚合反应,大幅度地降低了引发剂用量,聚合物收率显著提高,并发现聚合过程中不存在链终止反应．产物...     

CH3COSbCl6催化四氢呋喃聚合的研究

ＣＨ_３ＣＯＳｂＣｌ_６催化四氢呋喃聚合的研究栗方星，王红军，马克勤（南开大学化学系，天津，３０００７１）关键词聚四氢呋喃，乙酰基六氯锑酸盐，表观聚合反应速率常数，五氯化锑ＴＨＦ聚合为平衡聚合反应应［１，２］，文献报道［３，４］Ｅｔ３ＯＢＦ４、Ｅｔ３Ｏ...     

3-甲基-3-氧杂丁环甲醇的阳离子型开环聚合

三元和四元环醚具有较大的环张力而易于聚合．Ｖａｎｄｅｎｂｅｒｇ等［１］曾经以（ｉ－Ｂｕ３）Ａｌ／Ｈ２Ｏ为引发剂,使３－甲基－３－（三甲基硅氧甲基）氧杂丁环进行开环聚合反应,合成的聚合物水解后得到线形的聚甲基羟甲基醚．本文以ＢＦ３·ＯＥｔ２为引发剂,对３－甲基－３－氧杂丁环甲醇进行直接引发,实现了开环聚合反应,得到基本线形或轻度支化的聚醚多元醇．１　实验部分１．１　聚合物的合成　聚合装置同文献［１］．所用试剂按文献［１］方法处理．向烧瓶中加入２０ｍＬ的二氯乙烷和０．１ｍｏｌ３－甲基－３－氧杂丁环甲…     

杂多酸引发四氢呋喃开环聚合反应Ⅵ.以环氧氯丙烷为促进剂

在以低浓度杂多酸(ＨＰＡ)催化四氢呋喃(ＴＨＦ)聚合反应中,我们曾采用环氧乙烷(ＥＯ)和环氧丙烷(ＰＯ)为促进剂,发现它们都具有很好的促进效果[1,2],并且活性相近.在以三氟化硼(ＢＦ3)为催化剂的四氢呋喃正离子开环聚合反应中,促进剂的活性次序为:ＥＣＨ(环氧氯丙烷)>ＰＯＥＯ[3].在ＨＰＡ催化ＴＨＦ聚合反应中,ＥＣＨ是否仍具有高的促进活性是本文研究的目的.1　原料及聚合操作ＴＨＦ的纯化见文献[4],ＥＣＨ的纯化见文献[5],十二磷钨杂多酸(ＰＷ12)的处理见文献[1],三氟醋酸酐的合成方法和聚合反应的操作均见前文[2].2　分析测试核磁共振…     

二(芳氧基)稀土(Ⅱ)配合物催化ε-己内酯开环聚合

系统地研究了二（２，６ 二叔丁基 ４ 甲基酚基）钐［（ＡｒＯ）２Ｓｍ（ＴＨＦ）４］催化ε 己内酯的开环聚合，发现它具有很高的催化活性并显示“活性”聚合的特点，在甲苯中，当［Ｍ］／［Ｉ］＝２０００（摩尔比），６０℃，１ｈ，转化率可达９８％．并比较了不同的两价稀土化合物的催化活性．通过核磁分析末端基结构的方法，研究了（ＡｒＯ）２Ｓｍ催化己内酯开环聚合的引发机理，发现催化剂首先与己内酯反应，生成三价烯醇式稀土化合物，后者引发己内酯聚合．     

杂多酯引发四氢呋喃开环聚合反应Ⅶ.以氧杂环丁烷为促进剂

在以低浓度杂多酸(ＨＰＡ)催化四氢呋喃(ＴＨＦ)聚合反应中,我们曾采用环氧乙烷(ＥＯ)、环氧丙烷(ＰＯ)和环氧氯丙烷(ＥＣＨ)等三元环醚为促进剂,发现它们对聚合反应都具有很好的促进效果[1～3].本文进一步研究了具有四元环醚结构的氧杂环丁烷(ＯＸ)对ＴＨＦ聚合的促进效果.ＯＸ用作促进剂有以下优点,由ＯＸ促进ＴＨＦ聚合所得聚醚的端羟基为伯羟基,作为生产嵌段聚醚氨酯或嵌段聚酯弹性体的原料具有与四氢呋喃均聚醚相似的高反应活性;与ＥＯ相比,后者虽然促进ＴＨＦ聚合所得聚醚的端羟基也为伯羟基,但其沸点过低,不利于操作和贮存.1　原料及…     

杂多酸催化四氢呋喃开环聚合反应

以磷钼杂多酸作催化剂，环氧氯丙烷为促进剂，水或乙二醇为链调节剂，四氢呋喃开环聚合制备均聚醚的最佳工艺条件为：O℃－2℃，反应4h产率达64．5％，分子量在2000以内。用其制得的聚氨酯弹性材料与进口样品性能相当，某些性能优于进口原料制成的树脂。     

四氢呋喃阳离子聚合向丁二酸酐链转移反应的研究

四氢呋喃阳离子聚合向丁二酸酐链转移反应的研究魏斌，赵庆香，栗方星（南开大学化学系天津３０００７１）关键词聚四氢呋喃，五氯化锑，表现链转移速率常数，表现聚合反应速率常数前言在用ＣＨ３ＣＯＳｂＣｌ５引发的四氢呋喃阳离子聚合［１］过程中，我们发现存在着活性...     

开环移位聚合研究进展

关于开环移位聚合（Ｒｉｎｇ－ＯｐｅｎｉｎｇＭｅｔａｔｈｅｓｉｓＰｏｌｙｍｅｒｉｚａｔｉｏｎ,ＲＯＭＰ）的报导,最早始于５０年代末．１９６０年,Ｅｌｅｕｔｅｒｉｏ［１］用ＬｉＡｌＨ４激活的氧化铝催化降冰片烯（Ｎｏｒｂｏｒｎｅｎｅ,ＮＢＥ）、环戊烯的开环...     

杂多酸引发四氢呋喃开环聚合反应Ⅶ.以氧杂环丁烷为促进剂

在以低浓度杂多酸(HPA)催化四氢呋喃(THF)聚合反应中,我们曾采用环氧乙烷(EO)、环氧丙烷(PO)和环氧氯丙烷(ECH)等三元环醚为促进剂,发现它们对聚合反应都具有很好的促进效果[1～3]. 本文进一步研究了具有四元环醚结构的氧杂环丁烷(OX)对THF聚合的促进效果.     

杂多酸引发四氢呋喃聚合反应

八十年代中、后期发现，杂多酸（ＨＰＡ）是阳离子聚合反应的良好引发剂［１，２］．ＨＰＡ是一类酸强度比浓硫酸还高的质子酸［３］，不仅具有易于制备，结构稳定，腐蚀性低，易溶于大多数有机溶剂的特点，更为重要的是，ＨＰＡ可以回收和重复使用．因此，ＨＰＡ作为一类...     

杂多酸引发四氢呋喃开环聚合反应Ⅷ.以1,1,1-三羟甲基丙烷为分子量调节剂

Polyether triol with molecular weight distribution index being 1.3～1.5 was prepared in yield around 50% by tetrahydrofuran polymerization using heteropolyacid-H-3PW12O40 and ethylene oxide as initiator system and 1,1,1-trihydroxymethylenepropane(TMP) as molecular weight controller.The average hydroxyl functionality was estimated by end-group analysis and VPO to be close or equal to 3. The 1H-NMR　spectra showed that about 1/3 hydroxyl of TMP did not react with the propagating chains in the THF polymerization.Each of the unreacted hydroxyl groups of TMP attached to the middle or to the end of a diol chain as a pendent primary hydroxyl group forming the obtained polyether triol. All the hydroxyls of polyether triol were verified to be active enough towards 4,4′-methylene bis(phenyl isocynate) in the preparation of polyurethanes.     

MeOH/BF_3体系引发异丁烯阳离子聚合反应中水含量及聚合温度的影响

研究了水含量和聚合反应温度Tp 对MeOH BF3体系引发异丁烯 (IB)阳离子聚合反应的转化率、产物的分子量及分子量分布的影响 ,求出在不同水含量条件下的Tp 对聚合物分子量影响的数学方程及相应的聚合度活化能Ep ,以期对体系中存在的微量水加以充分利用 .结果表明 ,[H2 O]和Tp 两者共同影响IB阳离子聚合反应过程及产物的分子参数 .当Tp 由 - 10 0℃升高至 - 5 0℃时 ,聚合转化率先增加到一定值后再减小 ,在- 80℃～ - 70℃范围内出现峰值 .在 [H2 O]较低时 ,Tp 明显影响着聚合产物的分子量及分子量分布 ,Tp 越低 ,分子量越高 ,分子量分布越窄 ;在 [H2 O]较高时 ,Tp 对分子量的影响程度较小 ,说明此时水对聚合反应的影响更为突出 .体系中水含量增大对IB阳离子聚合反应呈现不利作用 ,当 [H2 O]由 1 5× 10 - 3mol L增加至 4 6×10 - 3mol L时 ,Ep 由 - 4 0kJ mol增大至 - 17kJ mol ,说明随着 [H2 O]增大 ,水的负面效应更加明显 ,既促进副反应 ,又阻碍链增长反应 ,增长活化能增大 ,聚合物分子量降低 ,分子量分布变宽 .水的负面作用也随着Tp 升高而变得明显 .     

Multihollow structured poly(methyl methacrylate)/silver nanocomposite microspheres prepared by suspension polymerization in the presence of dual dispersion agents

Poly(methyl methacrylate) (PMMA)/silver nanocomposite microspheres with unique multihollow structures were prepared by suspension polymerization in the presence of dual dispersion agents. The addition of a lipophilic emulsifier, polyethylene glycol (30EO) dipolyhydroxystearate (Arlacel P135), not only stabilized water-in-oil (W/O) emulsion, but also converted silver nanoparticles from hydrophilic to lipophilic. When a suspension polymerization dispersion agent, poly(vinyl alcohol), was added to the above W/O emulsion system, a water-in-oil-in-water suspension was formed with silver nanoparticles dispersed in the oil phase. The suspension polymerization was carried out at low temperature with 2,2’-azobis(2,4-dimethylvaleronitrile) as the initiator. When modified silver nanoparticles were added, the rate of polymerization increased slightly. High monomer conversion (about 85%) was obtained in spite of low polymerization temperature of 30 °C. Under controlled conditions, PMMA/silver microspheres with various hollow structures were synthesized. The PMMA/silver microspheres with multihollow structure showed high antibacterial ability.     

Chain termination in polymerization of substituted oxetanes in the presence of boron trifluoride etherate

It has been shown that the polymerization of oxetanes with azidomethyl substituents initiated by boron trifluoride etherate in the absence and the presence of ethylene glycol proceeds via chain termination with fluorine atom transfer. This reaction results in the formation of a polymer that is monofunctional with respect to hydroxyl groups and contains a fluorine atom at one of the chain ends. With the use of ¹⁹F NMR spectroscopy, the number-average functionality of polymer with respect to fluorine atoms was studied. The methods of suppressing the aforementioned reaction, whose intensity decreases during a decrease in the polymerization temperature and an increase in the ethylene glycol concentration, were considered. In the absence of ethylene glycol, the chain termination with fluorine atom transfer is the main reaction of chain-propagation restriction.     

Anion ring-opening polymerization of ethylene oxide by initiation of sodium 4-amino-N-(2-pyrimidinyl)benzene sulfonamide and influence of moisture on polymerization

Polyethylene oxide with sulfadiazine and hydroxyl end groups (PEOsf) were prepared by anion ring-opening polymerization of ethylene oxide initiated by sodium 4-amino-N-(2-pyrimidinyl)benzene sulfonamide (SF-Na). The product was characterized in detail by NMR, IR, GPC and DSC. Its molecular weight and molecular weight distribution are in the range of 1200-1 500 and 1.04-1.06 respectively, and the latter is nearly monodistribution. The trace of the moisture from air could accelerate the polymerization, and the mechanism is discussed.