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。     

异丁烯-co-对甲基苯乙烯的合成研究

以二枯基氯(DCC)、四氯化钛(Ti Cl4)、2,6-二叔丁基吡啶(Dt BP)为合成原料,通过活性正离子聚合成功地合成了不同异丁烯和对甲基苯乙烯进料比、不同聚合时间下的聚(异丁烯-co-对甲基苯乙烯)无规共聚物。通过TG以及DSC对产物进行表征。结果表明,无规共聚物的单体转化率与分子量呈线性关系,分子量分布窄,具有活性聚合的特征。     

异丁烯-对甲基苯乙烯无规共聚物的合成与表征

以二枯基氯/四氯化钛/2,6 -二叔丁基吡啶为引发体系,在-80℃条件下采用正离子聚合法合成了异丁烯-对甲基苯乙烯无规共聚物(IB -co -p - MeSt),研究了不同单体投料比(摩尔比)下聚合反应的特征,并通过示差折光指数仪/多角激光光散射仪/紫外检测器、核磁共振氢谱、差示扫描量热法和热重分析对无规共聚物进行了表...     

异丁烯与对甲基苯乙烯共聚合反应竞聚率的测定

在-80℃下,以2-氯-2,4,4-三甲基戊烷(TMPCl)/四氯化钛(TiCl4)/2,6-二叔丁基吡啶(DtBP)为引发体系,氯甲烷(CH3Cl)/环己烷(Chx)(体积比为50/50)为溶剂采用正离子聚合技术研究异丁烯与对甲基苯乙烯的共聚行为。研究异丁烯与对甲基苯乙烯不同投料比以及不同转化率下的共聚组成,利用Kelen-Tudos与Yezreielv-Brokhina-Roskin法计算单体的竞聚率;用1 H-NMR方法测定异丁烯和对甲基苯乙烯共聚物组成。结果表明,在低转化率(小于15%)的条件下,异丁烯与对甲基苯乙烯的竞聚率分别为r1=0.248,r2=1.190。     

异丁烯-对甲基苯乙烯无规共聚物可见光溴化反应的选择性

使用气相色谱仪对几种不同纯度的正己烷和环己烷进行了组分分析,并对包括2-甲基戊烷、3-甲基戊烷和甲基环戊烷在内的正己烷的主要支链型同分异构体成分,以及异丁烯-对甲基苯乙烯无规共聚物中对甲基苯乙烯结构单元的模型分子对二甲苯和对二异丙苯在波长为365～840 nm的可见光照射下的光溴化反应进行了对比,筛选出可以有效避免溶剂发生光溴化副反应并提高目标光溴化反应选择性的可见光波长。此外,将异丁烯-对甲基苯乙烯无规共聚物在质量分数为85.740 0%～99.960 0%的溶剂正己烷和环己烷中的光溴化反应的选择性进行了对比,并考察了除酸剂碳酸氢钠和反应温度对异丁烯-对甲基苯乙烯无规共聚物在正己烷中光溴化反应的影响。结果表明,波长为595 nm和630 nm的可见光可作为异丁烯-对甲基苯乙烯无规共聚物光溴化反应的光源,在质量分数为85%的工业正己烷中即可实现良好的光溴化反应,溴的有效利用率可达到70%～80%;碳酸氢钠作为酸蚀剂可以有效抑制异丁烯-对甲基苯乙烯无规共聚物的凝胶化反应。此外,反应温度对光溴化反应有一定影响,当反应温度从5 ℃降至-20 ℃时,溴化反应速率降低了58.87%。     

溴化异丁烯-对甲基苯乙烯共聚物的特点及应用

溴化异丁烯-对甲基苯乙烯共聚物(BIMS)除了具有丁基橡胶的优良气密性和阻尼性外,还表现出更好的耐热性(优于三元乙丙橡胶)、耐臭氧性、耐候性。在轮胎胶料中并用BIMS,可以改善动态性能,降低滚动阻力和提高抗湿滑性能,其应用正在逐渐拓展。     

溴化异丁烯-对甲基苯乙烯共聚物发泡材料的制备及性能

以氮气为物理发泡剂,采用间歇式发泡法对溴化异丁烯-对甲基苯乙烯共聚物(BIMSM)基体材料进行发泡,研究了高岭土用量及发泡温度对BIMSM发泡材料力学性能及泡孔结构的影响。结果表明,在相同发泡温度下,随着高岭土用量的增加,发泡材料的密度、邵尔C硬度、拉伸强度及撕裂强度均增大,泡孔尺寸呈先增大后减小的趋势,泡孔密度则先减小后增大,泡孔分布不均匀程度增加。当高岭土用量相同时,随着发泡温度的升高,发泡材料的密度、邵尔C硬度、拉伸强度及撕裂强度均降低,泡孔尺寸增大,泡孔分布更加均匀。     

苯乙烯-马来酸酐无规共聚物的研究进展

介绍苯乙烯(St)-马来酸酐(MAH)无规共聚物(R-SMA)的发展历程和聚合机理,分析R-SMA合成的影响因素,总结近年来R-SMA的主要聚合方法,并对R-SMA的未来发展进行展望。MAH与St极易进行交替聚合,可以通过提高温度和加入极性溶剂抑制交替聚合倾向,以合成R-SMA。溶液聚合法R-SMA具有传热效率高、可控性好的优点。在极性溶剂选择上,选择一种或多种混合环保型溶剂代替传统有机溶剂是需要解决的问题。     

DMS溶液法合成苯乙烯-马来酸酐无规共聚物

以环保型溶剂丁二酸二甲酯(DMS)为溶剂、苯乙烯(St)和马来酸酐(MAn)为共聚单体,采用溶液聚合法合成了苯乙烯/马来酸酐无规共聚物(R-SMA)。分析了溶剂浓度、单体摩尔比等反应条件对共聚物的影响,并且将其与传统常用溶剂丁酮进行对比。利用红外光谱(FTIR)表征R-SMA化学结构,采用凝胶气相色谱(GPC)测定其分子量及分子量分布,采用差示扫描量热法(DSC)、热重分析法(TGA)分析了R-SMA的热性能。实验结果表明,在溶剂DMS质量分数为70%、St/MAn摩尔比为75/25、反应温度为120℃条件下,R-SMA收率为82.9%、数均分子量(M_n)为18 111,分子量分布指数(PDI)为2.0。与丁酮作溶剂相比,当DMS作为溶剂时,产物的相对分子质量及马来酸酐含量较好,耐热性相近。     

Dynamics of continuous isobutylene cationic polymerizations

Polyisobutylene can be produced in either continuous cationic precipitation or solution polymerization reactors. It is known that the open-loop behavior of polymerization reactors may be very complex and may lead to oscillatory behavior, which is usually caused by thermal positive feedback (due to the large heats of reaction of polymerization reactions) and high viscosity effects (such as the gel effect in radical polymerization reactors and the decrease of heat transfer coefficients at high polymer concentrations). Oscillatory behavior may be observed in industrial isobutylene reactors, and it is intended to know whether these oscillations are inherent to the kinetic mechanism. Based on published experimental data, mathematical models are developed for both solution and precipitation processes. Steady-state solutions are calculated and steady-state stability is analyzed. Dynamic simulations and stability results reveal that only single stable steady-state solutions are possible for such reactors at usual operation conditions, which means that oscillatory behavior is not intrinsic to the reaction mechanism. © 1996 Wiley & Sons, Inc.     

VAC与DMC共聚合制备正离子型无皂乳液

以偶氮二异丁基脒酸盐（AIBA）为引发剂，用乙酸乙烯酯（VAC）与甲基丙烯酰氧乙基三甲基氯化铵（DMC）单体进行无皂乳液聚合，制备了正离子型无皂乳液。结果表明，增加DMC单体的质量分数和采用连续加料方式能够提高乳液的总固物质量分数和稳定性，同时连续加料聚合可以得到均匀、粒径较小的粒子。     

Slow initiation by tert-butoxybenzenes in living cationic polymerization of isobutylene

Summary tert-Butoxybenzenes including the 4-substituted derivatives of anisole, toluene and p-chlorobenzene have been synthesized and studied as initiators in combination with TiCl₄ for polymerization of isobutylene (IB) in CH₂Cl₂/methylcyclohexane (MeCHx) solvent mixtures at -78°C. Living polymerizations with slow initiation were observed by the allmonomer-in (AMI) and incremental monomer addition (IMA) techniques, and polymers with narrow molecular weight distribution (MWD) (M_w/M_n>1.1) were obtained under certain conditions. Aging of the initiating system prior to charging the monomer does not improve the initiating efficiency. It has been found that the initiating efficiency can be increased by increasing the solvent polarity, however, the relative volume of CH₂Cl₂ is limited in order to avoid polymer precipitation and bimodal MWD.     

三元共聚阳离子型聚丙烯酰胺的合成及应用

以丙烯酰胺(AM)、甲基丙烯酰氧乙基三甲基氯化铵(DMC)及二甲基二烯丙基氯化铵(DMDAAC)为原料,水溶性偶氮化合物为引发剂,采用水溶液聚合法合成了三元共聚阳离子型聚丙烯酰胺絮凝剂。考察了阳离子单体配比、单体质量分数、反应时间、引发剂用量及反应温度对聚合物相对分子质量的影响。结果表明,该三元共聚物的相对分子质量可达5.0×106,且水溶性好;对煤泥水具有良好的絮凝效果。     

异丁烯直接胺化制备叔丁胺研究进展

介绍了目前国内外叔丁胺的主要工业化制备方法,综述了异丁烯直接胺化制备叔丁胺的研究进展,并提出利用分子筛催化剂催化异丁烯直接胺化法是目前最有前景的叔丁胺制备方法。     

The anionic copolymerization behavior of the styrene: p-tert-butylstyrene and styrene:p-methylstyrene monomer pairs in benzene

Summary The anionic copolymerization of styrene:p-tert-butylstyrene and styrene:p-methylstyrene has been studied. In benzene, near statistical copolymers can be formed at 20°C when the lithium counter-ion is used. The addition of tetrahydrofuran (THF) is known to disrupt chain end association. The addition of THF(THF/Active center = 10) to the sytrene:p-tert-butylstyrene system led to virtually no change in the reactivity ratios.     

共聚合阳离子聚丙烯酰胺的合成及性能测试

首先合成阳离子单体N—(二甲氨基)甲基丙烯酰胺，然后用共聚合法合成阳离子聚丙烯酰胺。单体合成中探讨了经甲基二甲胺的合成工艺，当n(甲醛)：n(二甲胺)=2：1，反应温度为55℃，反应时间为2h时，羟甲基二甲胺的收率最高；并通过NMR确定了其结构。采用正交实验，研究了共聚合反应中n(丙烯酰胺)：n(阳离子丙烯酰胺)、温度、引发剂用量对聚合反应的影响。研究结果表明，n(丙烯酰胺)：n(阳离子丙烯酰胺)＝10：1，温度为45℃，引发剂质量分数为0．04％时，效果最佳，达到了一定的絮凝效果。     

Studies on cationic copolymerization of α-Methylstyrene and indene

Summary -Methylstyrene (MS) and indene (In) have been copolymerized in methylene chloride diluent using trityl ion salts, boron trifluoride methyl etherate, and trifluoroacetic acid as catalysts. Rate constants of homopolymerization of both monomers, copolymerization parameters (CPP) and individual rate constants (IRC) of binary first order copolymerization have been determined. The rate constants of trityl ion consumption in the presence of the monomers are qualitative measures of initiation rates. An interpretation of the differences of monomer reactivity in homopolymerization and copolymerization selectivity is proposed.     

Synthesis of linear isotactic-rich poly(p-methylstyrene) via cationic polymerization coinitiated with AlCl3

Cationic polymerizations of p-methylstyrene (pMS) with H₂O/AlCl₃/triphenylamine (TPA) or triethylamine (TEA) initiating system were carried out in mixed solvents of n-hexane and dichloromethane at ?80 ～ ?50 °C. The effects of TPA or TEA concentration, solvent polarity, polymerization temperature and time on monomer conversion, number-average molecular weight (M_n), molecular weight distribution (MWD, M_w/M_n), stereoregulatity and crystallinity of poly(p-methylstyrene) (PpMS) were investigated. The stereospecific cationic polymerization of p-methylstyrene could be achieved and high molecular weight (M_n = 116,000 ～ 436,000 g mol^?1) polymers with isotactic-rich segments (more than 75% of meso dyad) along macromolecular chains could be successfully synthesized. A possible mechanism for stereospecific cationic polymerization of pMS was proposed. The propagation proceeded via the dominant back-side attack and insertion of monomer from the growing ion paired species. The steric course of propagation was mainly determined by the tightness of the growing ion paired species and steric hindrance in counteranion. The resulting isotactic-rich PpMS could form crystal morphology with 10 ～ 30 μm in size by flow-induced crystallization under pressure at 180 °C. A possible model for the aligning mechanism was sketched to describe crystallization and to explain the multi-melting peaks and lower glass transition temperatures of PpMS. This is the first example of stereospecific cationic polymerization of p-methylstyrene to get crystallizable polymers with such high molecular weights and isotacticity.