“活性”原子转移自由基聚合向活性正离子开环聚合转化制备苯乙烯—2 …

以苯乙烯的ＡＴＲＰ聚合制备含卤端基的聚苯乙烯,再以此含卤端基的聚苯乙烯引发２－甲基－２－恶唑啉的正离子开环聚合,合成了苯乙烯与２－甲基－２－恶唑啉嵌段共聚物,并用ＩＲ,ＧＰＣ对开环产物进行了表征。     

以聚（异戊二烯-苯乙烯）嵌段共聚物为“接枝剂”活性碳正离子聚合制备星形支化丁基橡胶

通过活性负离子聚合制备的聚（异戊二烯-苯乙烯）嵌段共聚物作为“接枝剂”,在2-氯-2,4,4-三甲基戊烷/TiCl4/质子捕捉剂的引发剂体系中,通过活性碳正离子聚合制备了星形支化丁基橡胶。结果表明,聚（异戊二烯-苯乙烯）嵌段共聚物的接枝效果明显,所得聚合物的空间排斥色谱图呈现明显的双峰,相对分子质量分布加宽;     

以聚(异戊二烯-苯乙烯)嵌段共聚物为"接枝剂"活性碳正离子聚合制备星形支化丁基橡

通过活性负离子聚合制备的聚(异戊二烯-苯乙烯)嵌段共聚物作为"接枝剂",在2-氯-2,4,4-三甲基戊烷/TiCl4/质子捕捉剂的引发剂体系中,通过活性碳正离子聚合制备了星形支化丁基橡胶.结果表明,聚(异戊二烯-苯乙烯)嵌段共聚物的接枝效果明显,所得聚合物的空间排斥色谱图呈现明显的双峰,相对分子质量分布加宽;高分子链可能存在支化现象.     

C60X／BCl3／AlEt2Cl催化异丁烯聚合

以新型球笼烯正离子催化剂Ｃ６０Ｘ／ＢＣｌ３／ＡｌＥｔ２Ｃｌ在－２５－－１５℃下引发异丁烯聚合。比较不同催化体系所得划丁烯的＾１Ｈ－ＮＭＲ谱图，发现并推断在（４．５－５．２）×１０＾－６处的吸收峰与Ｃ６０Ｘ参与引发发一转作用有关。     

活性正离子聚合向活性自由基聚合转化法合成嵌段共聚物

通过枯基氯／四氯化钛／吡啶／异戊二烯活性正离子聚合反应体系制备了末端是叔氯基的聚异丁烯,经过脱氯化氢反应其分子链末端转化成异丁烯基．在9-硼二环[3,3．1]壬烷、氧气存在下引发苯乙烯的活性自由基聚合,成功地合成了异丁烯-苯乙烯嵌段共聚物,并用核磁共振仪对所得产物进行了表征。     

异丁烯系共聚物的最新进展

本文简要介绍了异丁烯系共聚物的最新进展，对星形支化丁基橡胶，异丁类－对甲基苯乙烯共聚物及其溴化共聚物以及溴化丁基橡胶的改性等的合成，性能和应用进行了分析讨论，并提出加速研制生产丁基橡胶等的意见。     

正离子聚合制备异丁烯-对甲基苯乙烯无规共聚物及其溴化反应

通过正离子聚合法制备了异丁烯-对甲基苯乙烯无规共聚物,考察了单体浓度、聚合温度以及聚合时间对正离子聚合的影响,并通过光照溴化反应对共聚物进行溴化改性,制备出主链结构完全饱和的溴化异丁烯-对甲基苯乙烯无规共聚物(BIMS),对其结构与性能进行了表征。结果表明,在-80℃、单体质量分数为25%～28%时,异丁烯与对甲基苯乙烯正离子共聚合,聚合物的数均分子量可达2.1×10~5。随着温度的降低,聚合物的数均分子量增大,分子量分布变窄。随着溴含量的增加,BMIS中苄基溴含量也增加,当溴质量分数为1.9%时,聚合物中苄基溴摩尔分数达到1.38%。BIMS热稳定性较好,在较低的温度下仍能保持橡胶的高弹性,且耐热氧老化性能优异。     

大力开发高纯异丁烯的应用

根据美国著名咨询公司CMAI完成的题名为”2003年全球丁烯/MTBE市场分析”的研究报告分析,2002年全球异丁烯的需求量为1530万吨,CAMI公司预计在未来的几年中异丁烯的消费量将会以7.8％的速度降低,造成其需求量降低的主要原因是美国将会分阶段停止生产MTBE。 目前,我国乙烯副产异丁烯达30万吨,加上炼油厂C4中的异丁烯,总资源达40万吨以上。但这些异丁烯资源除用于合成甲基叙丁基醚MTBE外,大部分异丁烯混于C4中作液化气燃料烧掉,异丁烯资源浪费严重。虽然目前欧洲和亚洲尚未有表示禁用MTBE的意向,但世界范围内对MTBE污染性的争论给我国MTBE的发展笼罩了一层阴影,我国现有的MTBE装置达30余套,总生产能力已达70万吨·年~(-1)以     

2,6-二叔丁基吡啶在异丁烯活性正离子聚合中的作用研究

研究在-80℃条件下,以一氯甲烷和己烷为溶剂,2,6-二叔丁基吡啶(DtBP)对2-氯-2,4,4-三甲基戊烷(TMPCl)/四氯化钛(TiCl4)体系引发异丁烯(IB)正离子聚合反应的相对分子量及分子量分布、转化率的影响,并考察体系中DtBP浓度变化时,转化率对反应时间的函数关系,进行动力学研究。结果表明,DtBP在TMPCl/TiCl4/DtBP为引发体系,引发IB正离子聚合的过程中,有以下作用:1)质子捕捉作用,截获在引发阶段由杂质、水产生的质子和增长链端β-H脱除产生的质子;2)碳正离子稳定作用,降低聚合反应的表观速率,提高引发剂的引发效率,使非活性聚合过程转化为活性聚合过程。     

一种新型丁基橡胶淤浆稳定剂的合成与测评

通过负离子聚合技术,合成了一种星形聚苯乙烯-异戊二烯嵌段共聚物,并把它作为丁基橡胶的淤浆稳定剂和支化剂进行了测评。结果表明,合成的星形嵌段聚合物用量为0.5%～3%时,有稳定丁基橡胶淤浆的作用,且随着星形聚合物量的增加,淤浆稳定效果愈好,产品的相对分子质量分布愈宽;超出这个范围,有凝胶产物生成。     

分子模拟法研究亲核试剂在异丁烯正离子聚合反应中的作用机理

采用Chem3D中捆绑的MM2、MOPAC模拟不同体系的异丁烯引发反应及与亲核试剂作用所生成的分子结构，进行初步优化后使用Gaussian 98 revision A．9程序包对其可能的分子结构进行计算，根据电荷分布、键长等计算结果研究亲核试剂-六氢吡啶在异丁烯／苯甲酰氟／四氯化钛正离子聚合反应中的作用机理。     

Synthesis and characterization of star‐branched polyisobutylene with SIpS triblock copolymer core

Well‐defined polystyrene‐b‐polyisoprene‐b‐polystyrene (SIpS) triblock copolymers with different microstructures were synthesized by living anionic polymerization. The synthesis of star‐branched polyisobutylene (PIB) was accomplished by the cationic polymerization in 2‐chloro‐2,4,4‐trimethylpentane/titanium tetrachloride/SIpS triblock copolymer/2,6‐di‐tert‐butylpyridine initiating system. The double bonds in SIpS triblock copolymer were activated as starting points for isobutylene polymerization. The formation of star‐branched architecture was demonstrated by size‐exclusion chromatography with quadruple detection: refractive index, multiangle laser light scattering, viscometric, and ultraviolet detectors. SIpS triblock copolymer with high 3,4‐PIp content is more reactive than that with high 1,4‐PIp content in cationic initiating stage. The yields of star‐branched PIB were remarkably dependent on the reaction time of TMP⁺ with SIpS. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

国内丁基橡胶产业现状及发展建议

介绍了国内丁基橡胶的供需现状及国内外目前使用的生产方法,总结了丁基橡胶的星形支化技术和共混改性技术的进展,针对我国丁基橡胶产业存在的问题提出了应大力推进技术先进化?实现核心装备国产化以及产品高性能化的发展建议.     

A modified glass reactor for the preparation of linear and star-branched block copolymers via living anionic polymerization

A modular high-vacuum system for large-scale anionic polymerization reactions was designed that utilizes mechanical agitation in place of magnetic stirring, Teflon Rotoflo stopcocks in place of glass breakseals, and spherical o-ring joints in place of direct glass seals. A standard reactor body was used, and depending upon reactor design, it was fitted with appropriate reactant ampules, volumetric charging cylinders, etc., to facilitate polymerization, blocking reactions, and linking reactions with minimal effort. To demonstrate the efficacy of the system a number of linear and three-arm star-block copolymers comprised of oligostyrene outer blocks and polybutadiene inner blocks were synthesized. The block copolymers were characterized by narrow molecular weight dispersity, and the star polymers showed greater than 95% linking efficiency. The polybutadiene blocks contained approximately 40% 1,2-enchainment and were exhaustively hydrogenated using H₂ and a nickel octoate/triethyl aluminum catalyst. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 151–159, 1997     

Synthesis of polyvinyl alcohol stereoblock copolymer via the combination of living cationic polymerization and RAFT/MADIX polymerization using xanthate with vinyl ether moiety

Different types of novel xanthates containing a vinyl ether moiety, S-benzyl O-2-(vinyloxy)ethyl carbonodithioate (Xanthate 1) and S-1-(ethoxycarbonyl)ethyl O-2-(vinyloxy)ethyl carbonodithioate (Xanthate 2) were synthesized. In particular, the Xanthate 2 enabled to design polyvinyl alcohol (PVA) stereoblock copolymer via the combination of living cationic vinyl polymerization and RAFT/MADIX polymerization. For cationic polymerization of isobutyl vinyl ether (IBVE) and tert-butyl vinyl ether (TBVE), the polymerizations were conducted under Xanthate 1-HCl adduct/SnCl₄ and Xanthate 1 or 2-CF₃COOH adduct/EtAlCl₂ initiating system in the presence of ethyl acetate. Both systems proceeded in living polymerization fashion because the calculated M_n of both poly(IBVE) and poly(TBVE) matches with the M_n polymerized assuming that one polymer chain is formed per one molecule of the Xanthate 1 or 2. The resulting poly(TBVE) had a high number average α-end functionality as determined by MALDI-TOF-MS spectrometry. Xanthate 2 is more efficient for the following RAFT/MADIX polymerization of vinyl acetate (VAc). The RAFT/MADIX polymerization of vinyl acetate (VAc) using azobis(isobutyronitrile) (AIBN) at 60 °C was conducted using either poly(IBVE) or poly(TBVE) macro-CTA. The poly(TBVE) macro-CTAs synthesized from the Xanthate 2 were able to polymerize VAc smoothly via RAFT/MADIX polymerization, to prepare well-defined diblock copolymer, poly(TBVE)-b-poly(VAc). The resulting block copolymer was then hydrolyzed using KOH in methanol and followed by acid hydrolysis using HBr gas bubbling. The resulting polymer is inherently stereoblock like copolymer, isotactic rich PVA-b-atactic PVA (iPVA-b-aPVA). From the DSC measurement, the iPVA-b-aPVA has one glass transition at 69.5 °C and two melting points according to iPVA and aPVA at 237.9 and 198.1 °C, respectively. Thus, it can be suggested that the obtained PVA has two different geometries by the combination of living cationic polymerization and RAFT/MADIX polymerization.     

Synthesis of poly(cyclohexene oxide)‐block‐polystyrene by combination of radical‐promoted cationic polymerization,atom transfer radical polymerization and click chemistry

The combination of radical‐promoted cationic polymerization, atom transfer radical polymerization (ATRP) and click chemistry was employed for the efficient preparation of poly(cyclohexene oxide)‐block‐polystyrene (PCHO‐b‐PSt). Alkyne end‐functionalized poly(cyclohexene oxide) (PCHO‐alkyne) was prepared by radical‐promoted cationic polymerization of cyclohexene oxide monomer in the presence of 1,2‐diphenyl‐2‐(2‐propynyloxy)‐1‐ethanone (B‐alkyne) and an onium salt, namely 1‐ethoxy‐2‐methylpyridinium hexafluorophosphate, as the initiating system. The B‐alkyne compound was synthesized using benzoin photoinitiator and propargyl bromide. Well‐defined bromine‐terminated polystyrene (PSt‐Br) was prepared by ATRP using 2‐oxo‐1,2‐diphenylethyl‐2‐bromopropanoate as initiator. Subsequently, the bromine chain end of PSt‐Br was converted to an azide group to obtain PSt‐N₃ by a simple nucleophilic substitution reaction. Then the coupling reaction between the azide end group in PSt‐N₃ and PCHO‐alkyne was performed with Cu(I) catalysis in order to obtain the PCHO‐b‐PSt block copolymer. The structures of all polymers were determined. Copyright © 2010 Society of Chemical Industry     

Emulsifier-free emulsion polymerization of N-butyl methacrylate

A cationic polymer of n-butyl methacrylate was prepared in an emulsifier-free system. Using, as a base, a 30% solid content, the variables studied were the monomer and initiator concentrations, the agitation, and the temperature. The molecular weight, the zeta potential, and the particle size were determined. The results are compared with earlier work done on similar systems. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1711–1719, 1998     

微反应器内丁基橡胶溶液法制备体系的反应特性研究

研究了微反应器内丁基橡胶溶液法制备体系的反应规律。结果表明以H₂O为质子源、EtAlCl₂为共引发剂时,控制反应温度为-60℃、水含量在0（control）到0.27 mmol/L之间,可在分钟级时间内高转化率地得到数均分子量高于300000的聚异丁烯产品,此时链转移得到有效抑制,强化反应物料的初始混合对提升产品质量有利;引入异戊二烯会显著降低产物分子量和转化速度,可以通过使用酸性更弱的Et₂AlCl代替EtAlCl₂来稳定碳阳离子,抑制链转移,在-60℃下得到数均分子量接近150000的共聚产物,但反应速度缓慢,需要进一步优化和控制反应体系中的水含量来强化该过程。     

光引发阳离子聚合及其在环氧树脂固化研究中的进展

从光引发阳离子聚合的特点、常见阳离子型光敏引发剂及其引发聚合机理、光引发环氧树脂阳离子聚合体系及发展前景等几个方面进行了简要概述。     

Block copolymers of cyclohexene oxide and ketonic resins via condensation and promoted cationic polymerization

Block copolymers of cyclohexene oxide (CHO) and ketonic resin were prepared by using ketonic resins as free radical photoinitiators via two‐step procedure. In the first step, cyclohexanone–formaldehyde and acetophenone–formaldehyde resins were modified during their preparation with benzoin and benzoin isobutyl ether. Then, AB or ABA type block copolymers depending on the resin employed were obtained by irradiation of these resins in the presence of pyridinium salt and CHO as a cationically polymerizable monomer. By this way, block copolymers of CHO with ketonic resin were prepared and characterized by GPC, DCS, FTIR, and ¹H NMR spectral measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007