单取代芳氧钛合成与催化乙烯及乙烯与α-烯烃共聚

使用廉价原料和简单工艺方法合成了芳氧钛类烯烃聚合和共聚催化剂,得到了(2-OMe C6H4O)Ti Cl3(C1),(2,4-Me2C6H3O)Ti Cl3(C2),Ti Cl3(1,4-OC6H4O)Ti Cl3(C3),Ti Cl3(1,4-OC6H2O-Me2-2,5)Ti Cl3(C4)以及相应的(Ar O)2Ti Cl2类络合物Ti Cl2(OC6H4-OMe-2)2(C5)和Ti Cl2(OC6H3-Me2-2,6)2(C6).通过1H NMR,13C NMR,MS以及元素分析进行了结构表征,确认了化学组成,以甲基铝氧烷(MAO)为助催化剂,Ar OTi Cl3/MAO体系显示了对乙烯聚合和共聚的高活性,13C NMR结果表明,聚合物中1-己烯插入率最高达6.88%(摩尔分数),而且得到的聚合物呈现高度支化,除了α-烯烃支链,还有甲基、乙基和长支链,并对其形成机理进行了研究,此外,对聚合温度、时间及共聚单体浓度对聚合反应的影响也进行了探讨.     

四碘化钛-三異丁基铝催化体系制备顺式-1,4-聚丁二烯——Ⅰ.催化剂的活性和聚合物的性质

研究了丁二烯在苯中有四碘化钛-三异丁基铝催化剂的存在下的聚合。发现这一催化体系的活性取决于Al/Ti比和聚合温度。对每一四碘化钛用量出现一具有最高活性的“临界Al/Ti此”;低于这一Al/Ti比,活性完全消失;高于这一Al/Ti比则活性逐渐降低(图2)。 增加Al/Ti可以减慢聚合速度而不影响最终转化率(图3);因此,可以利用Al/Ti来控制这一聚合反应以防止反应混合物的积热现象(图4)。 这一催化体系的优点是不论在任何条件下,包括催化剂组成(例如Al/Ti)和聚合条件(例如温度),聚合物都不合凝胶,而顺-1,4-结构含量总能在90％以上(表2)。 聚合物的分子量取决于两个主要因素:四碘化钛用量和聚合温度;增加四碘化钛用量和升高聚合温度都降低分子量(图5和图6)。Al/Ti对分子量的影响则不甚明显(图6)。 用这种催化剂制得的顺-1,4-聚丁二烯的分子量分布很窄(图7);因此,虽然这是一个非均相催化体系,它的活性中心可能比较单纯,大概不会含有多种活性中心。     

膦手性丙炔胺脯氨酸磷酸酯螺旋聚合物的合成与表征

通过添加对映体拆分剂,合成了4种含膦手性的丙炔胺磷酸酯单体[HC帒CC H2NH(PO)R1R2].单体1,R1=OPh,R2=NC4H7COOCH3;单体2,R1=OPh,R2=NC4H7COOCH2CH3;单体3,R1=OPh,R2=NC4H7-COOC(CH3)3;单体4,R1=Ph,R2=NC4H7COOC(CH3)3].1H-NMR和31P-NMR表征可知对映体(单体1)不能被拆分剂拆分,而单体2、单体3、单体4通过拆分剂可以制得单一手性的磷化合物.以(nbd)Rh+[η6-C6H5B--(C6H5)3]为催化剂,以三氯甲烷为溶剂成功得到聚合物分子量范围在0.4×10-4～0.7×10-4,分子量分布在1.26～1.98范围的3种含手性膦侧基的丙炔胺类聚合物.比旋光度([α]D)、圆二色谱(CD)对聚合物的不同侧基及温度对光学活性的影响表明,聚合物具有良好的光学活性且能够形成单一方向的螺旋构象,说明膦手性在构建螺旋聚合物具有重要作用.     

异双桥联茂金属催化剂催化丙烯聚合制备高分子量无规聚丙烯

采用2种分别具有Cs对称性和C1对称性的异双桥联茂金属催化剂(Me_2C)(Me_2Si)Cp_2TiCl_2、[(CH_2)_5C](Me_2Si)Cp_2TiCl_2,在助催化剂甲基铝氧烷(MAO)的作用下用于丙烯聚合.通过对聚合温度、助催化剂用量和聚合时间的研究,详细考察了这些因素对聚合活性和聚合物结构的影响.由核磁共振碳谱(13CNMR)、示差扫描量热分析(DSC)和凝胶渗透色谱法(GPC)表征了所得聚合物的结构和分子量及分子量分布.这2种催化剂催化丙烯常压聚合活性最高可达10~6g PP/mol·h,重均分子量可达7×10~5,分子量分布在2.0左右,所得聚丙烯为高分子量的无规聚丙烯.这两种异双桥联茂金属催化体系在低温下表现出良好的聚合活性;但聚合温度升高,聚合活性和聚丙烯的分子量呈现明显的下降趋势.随铝钛比的增加,聚合活性和聚合物分子量均呈现先上升后降低的趋势.聚合时间增加活性下降,聚合物分子量有所增加.研究表明,这2种催化剂具有的大二面角(71.0°,70.3°)结构对催化性能和聚合物的结构有较大影响.     

钛(Ⅳ)催化Meerwein-Ponndorf-Verley-Oppenauer反应

本文研究了各种Ti(Ⅳ)化合物:Ti(OR)_4(R=Et,~iPr,~nBu),TiCl_4,CP_2TiC_2,Cp_2Ti(OPh)_2对Meerwein-Ponndorf-Verley-Oppenauer反应的催化活性。试验表明Ti(O~iPr)_4对还原反应显示出极好的催化活性,还原苯甲醛,对氯苯甲醛,对硝基苯甲醛,对甲氧基苯甲醛,糠醛,巴豆醛的产率可达80％以上。Ti(OEt)_4对氧化反应有良好的催化活性,对正辛醇,2-辛醇,苯甲醇,环已醇,肉桂醇的氧化产率在69％以上。同时还考察了各种参数对反应的影响。     

单茂钛催化剂催化丁烯-1聚合及高分子量无规聚丁烯-1的合成与表征

Kaminsky等 [1,2 ] 用二茂基 ( Cp,Ind,Flu)过渡金属 ( Ti,Zr和 Hf)化合物 /MAO催化剂催化丁烯 - 1聚合 ,得到间规 -等规或间规 -等规 -无规的混合物 ,聚合物的分子量为 5 0 0 0 0至 1 5 0 0 0 0 .Rossi[3] 用( CH3) 2 Si( H4 Ind) 2 Zr Cl2 /MAO研究了丁烯 - 1的等规聚合 ,产物分子量仅 2 0 0 0左右 .林尚安等[4 ,5] 采用单茂钛催化剂 Cp* Ti( OBz) 3/MAO催化丁烯 - 1聚合 ,产物为立体多嵌段聚丁烯 - 1 .但目前尚未见到有关采用茂金属催化剂催化丁烯 - 1聚合制备高分子量无规弹性体聚丁烯 - 1的报道 .我们用单茂钛 Cp* Ti( OC…     

Nd(O-i-Pr)3-Al(i-Bu)3配位催化甲基丙烯酸甲酯聚合反应的研究

甲基丙烯酸甲酯(MMA)能以自由基引发聚合,也能以格氏试剂、烷基锂或烷基铝引发阴离子聚合[1].六十年代来,ABE等人研究了Ti、V、Cr、Co、Mn等的Ziegler-Natta催化剂的催化聚合反应,提高聚合物的规整性[2].近年来出现了稀土配位催化聚合MMA及其它丙烯酸酯的报道[2～7],但较少有Nd(O-i-Pr)3配位催化MMA聚合的报道.     

超分子聚合机理

与共价键聚合物由单体(M1)通过共价键连接不同,超分子聚合物是由单体(M2)通过非共价键连接而成的长链大分子。聚合包括分子聚合和超分子聚合。超分子聚合描述M2通过非共价键自组装形成超分子聚合物的过程,涉及氢键、π-π堆砌型和立体匹配等驱动力以及分子识别、协同性等特征,与M1通过共价键形成聚合物的过程(分子聚合)不同。为了理解超分子聚合物链结构形成机理,本文分析和讨论超分子聚合的三个主要机理:(1)线性链生长;(2)螺旋链生长;(3)拓扑链生长。     

(n-BuCp)_2TiCl_2/Sn/I_s引发合成梳形羟基功能化无规聚苯乙烯及聚合物结构与性能的研究

采用茂金属化合物(n-BuCp)2TiCl2,还原剂(Sn),引发剂苯基缩水甘油基醚甲醛共聚物(Is)组成的催化体系引发苯乙烯活性自由基聚合,合成梳形羟基功能化无规聚苯乙烯.考察了聚合温度、聚合时间及引发剂与单体的比例对苯乙烯聚合的影响.当聚合温度在65～95℃范围内,随着聚合温度的升高,聚合物的分子量及单体转化率增加;在一定温度下,聚合物的分子量与单体转化率之间存在线性增长关系,且聚合物的分子量分布较窄(Mw/Mn=1.6～1.9).采用GPC,WAXD,13C(1H)-NMR对聚合物(沸丁酮可溶级分)的结构与性能进行了表征.GPC结果证明(n-BuCp)2TiCl2/Sn/Is引发苯乙烯聚合为活性聚合;13C-NMR和WAXD结果说明聚苯乙烯链段为无规结构;1H-NMR结果表明聚合物分子链中含有羟基,并根据其结果计算出聚合物分子的臂数为4,与引发剂Is的环氧基团数相等.这些结果证明了其聚合机理是经环氧基团开环后形成的自由基引发苯乙烯自由基聚合.     

光引发氮氧自由基调控聚合反应研究进展

氮氧自由基调控聚合(NMP)是制备微观结构可控(如窄分子量分布)的聚合物材料最主要的技术手段之一。在过去的二十年间,NMP取得了相当大的成就,实现了MMA、n-BA、丙烯酰胺,二烯烃和丙烯腈等多种单体的可控/"活性"聚合,分子量分布达到1.1以下,同时利用NMP制备了具有既定结构的聚合物,如嵌段聚合物、接枝聚合物、星形聚合物和梳形聚合物等。而与光聚合技术的结合,使NMP聚合取得了更大的突破,实现了室温下的光可控/"活性"聚合,且大大提升了聚合反应速率。近年来光引发氮氧自由基调控聚合的研究进展主要集中在光敏化技术方面,包括分子内敏化和分子间敏化,本文对其各自的敏化机理和研究成果进行总结和评述,希望有助于国内读者了解这方面研究工作的状况,促进国内相关研究工作的发展。     

Polymerization of n-octadecene-1 with catalysts derived from titanium tetrachloride and triethylaluminum

The effects of variation in Al/Ti mole ratio, catalyst concentration, reaction time, and temperature on the yield and some physical properties of polymers of n-octadecene-1 obtained with the use of Ziegler catalyst systems derived from titanium tetrachloride and triethylaluminum have been investigated. Results show many features similar to those obtained by other workers with lower olefins. In general, the yield of polymer shows a distinct maximum at an Al:Ti mole ratio of 2.8:1 and total catalyst concentration (at the stated mole ratio) of 4%, based on monomer; the yield increases sharply with polymerization temperature to a maximum at about 40°C. and with time up to about 12 hr. at 25°C. Polymer intrinsic viscosity also shows a strong dependence on Al:Ti mole ratio and catalyst concentration, increasing between Al:Ti mole ratios of 2.0–3.4, and showing a maximum at catalyst concentration of 3.5% on monomer. Polymer intrinsic viscosity shows a decrease with increasing reaction temperature and an increase with time of polymerization. The polymer densities, melting points, and fraction soluble in hexane (at 25°C.) appear to show much less dependence on the variables under consideration, and no firm conclusions are drawn. An important reaction concurrent with polymerization is the formation of a trans nonterminal isomer of octadecene. This certainly affects the yield (the nonterminal isomer not being polymerizable under the same conditions); the effect of the presence during polymerization of isomerized monomer on the physical characteristics of the polymer is less clear, and further work is proceeding.     

MgCl_2负载(dbm)_2Ti(OPh)_2催化乙烯聚合

烯烃聚合的新型非茂催化剂由于合成相对简便并具有一些新特点,近年来开始受到人们的关注[1,2].ＩＶＢ族金属的β二酮络合物与烷基铝或烷氧基铝形成的催化体系对烯烃聚合也显现出一定的聚合活性.在一定压力下,β二酮锆/ＭＡＯ均相催化乙烯聚合时具有较高聚合活性[3].β二酮钛催化剂对于丙烯无规聚合和苯乙烯间规聚合均有较好结果[4～6].本文将报道用ＭｇＣｌ2负载的二苯氧基二(二苯甲酰甲烷)钛络合物((ｄｂｍ)2Ｔｉ(ＯＰｈ)2),以甲基铝氧烷(ＭＡＯ)为助催化剂,常压催化乙烯聚合的结果.1　原料ＭｇＣｌ2为抚顺301厂产品.ＭＡＯ(1.4ｍｏｌ/Ｌ甲…     

Effects of Al(i-Bu)_3 on Propylene Polymerization and Copolymerization by rac-Me_2Si(Ind)_2ZrCl_2/MAO

Propylenepolymerizationbystereorigidansa-Inetallocene/meUlyI-alulhinoxane(MAO)havebeenreportedbymanygroupsinrecentyears."'PolypropylenefromsuchSystemhasthechacteristicsofnarrowmolecularweightandcompositiondistributions,whichcannotbeproducedbytheconditionalheterogeneousZiegler-Nattacatalysts.Inarecentwork,M.C.SacchietaLrepoftedUleeffectsofaddingAl(i-C4Hg)3ahA)totherac-Et(Ind)ZZrCI,/MAOcatalyzedpropylene/1-hexenecopolymerizationSystem.'ItwasfoundthatbyaddingcertainamountsofTBAhlepoly…     

可修饰的内酯，α-氯甲基-α-甲基-β-丙内酯的合成和聚合

可修饰的内酯，α－氯甲基－α－甲基－β－丙内酯的合成和聚合＊王明霞李子臣贺晓晖杨丽＊＊李福绵（北京大学化学系北京１００８７１）关键词α－氯甲基－α－甲基－β－丙内酯，开环聚合＊１９９５－０２－２０收稿；１９９６－０３－１２修回：自然科学基金课题；＊＊...     

Anionic polymerization of methyl methacrylate with Cr(C5H7O2)3–Al(C2H5)3 catalyst system

A homogeneous catalyst system, Cr(C₅H₇O₂)₃–Al(C₂H₅)₃, was used for the polymerization of methyl methacrylate. The yield of polymer increased up to an Al/Cr ratio of 12 and thereafter remained almost constant with increasing Al/Cr. The rate of polymerization increased linearly with increasing catalyst and monomer concentrations at Al/Cr = 12. The molecular weight, however, decreased with increasing catalyst concentration and increased with increasing monomer concentration, indicating anionic polymerization reaction. NMR studies of the polymers indicated the presence of a stereoblock structure, which changed to heteroblock structure in presence of triethylamine and hydroquinone as additives in the catalyst. In the light of these observations, the mechanism of the polymerization is discussed.     

稀土-其它过渡金属混合催化剂用于共轭双烯烃的聚合——Ⅳ.(NdCl_3+FeCl_3)·nphen-HAI(i-Bu)_2体系对异戊二烯的聚合

本文报道由(NdCl_3+FeCl_3)·nphen-HAl(i-Bu)_2催化体系引发异戊二烯聚合的结果。在适当Nd/Pe比下,该体系对异戊二烯聚合的活性可超过单一钕或铁催化剂的活性,同时随催化剂中钕和铁含量的不同,所得产物的微观结构变化很大,当体系中钕含量由100％→0时,产物的顺-1,4结构含量由94.4％→22.1％,而3,4结构含量由5.6％→77.9％。Al/M(N=Nd+Fe)比、单体浓度和聚合温度不仅对聚合活性有影响,对产物的微观结构影响也较大。事实表明,该聚合体系中存在着两种过渡金属(Nd和Fe)活性中心,它们按各自的机理进行异戊二烯的聚合。     

球形MgCl2负载的MAO/rac-Et[Ind]2ZrCl2催化剂催化丙烯 聚合

采用只在球形MgCl2上负载MAO,聚合前再同rac--Et[Ind]2ZrCl2预混的负载方式进行丙烯聚合。在少量AlEt3的活化下,很低的Al(MAO)/Zr摩尔比时即可获得比均相催化剂高一个数量级的活性,考察了温度、压力、Al(MAO)/Zr摩尔比和催化剂浓度对聚合的影响,同时用13^CNMR测定了均相和载体催化体系所制备的聚丙烯的微结构,发现负载型茂金属催化剂制得的聚丙烯立构规整性高于均相体系,其五元组立构序列[mmmm]可从均相的52.6%提高到负载催化剂的79.5%。扫描电镜观察表明,聚合物颗粒可较好地复制球形催化剂的颗粒形态。     

Soluble tin(II) macroinitiator adducts for the controlled ring‐opening polymerization of lactones and cyclic carbonates

Polyesters and poly(ester carbonates) were synthesized via ring‐opening polymerization with new tin(II) macroinitiator adducts containing oligomeric L ‐lactide (LLA), rac‐lactide (rac‐LA), and ?‐caprolactone (CL). The novel initiating species were synthesized by the reaction of LLA, rac‐LA, or CL with Sn(OEt)₂ (monomer concentration/initiator concentration ≤20) and then were dissolved in methylene chloride or toluene and stored in a stoppered flask for the subsequent ring‐opening polymerization of cyclic esters and carbonates. The soluble tin alkoxide macroinitiators yielded predictable and quantitative initiation of polymerization for up to 1 month of storage time at room temperature. The resulting polymers displayed low polydispersity (≤1.5), and a high monomer conversion (>95%) was obtained within relatively short polymerization times (≤2 h). Adjusting the monomer/macroinitiator ratio effectively controlled the molecular weights of the polymers. NMR was used to characterize the initiating species and polymer microstructure, and size exclusion chromatography was used to determine the molecular weight properties of the polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3434–3442, 2002     

Cyclo- and cyclized diene polymers. XVI. Nature of the active species and a proposed mechanism of cyclopolymerization of isoprene with catalysts containing ethylaluminum halides

The polymerization of isoprene with C₂H₅AlCl₂ to yield solid cyclopolyisoprene is markedly accelerated by the addition of TiCl₄. The polymer yield passes through a maximum on increasing the catalyst reaction time with or without monomer present. The active species are probably cations formed by dissociation of the reaction product of C₂H₅AlCl₂ and TiCl₄. The polymerization of isoprene with (C₂H₅)₂AlX–TiCl₄ (X = F, Br, Cl) has maximum activity at an Al/Ti mole ratio of 0.75 corresponding to conversion of R₂AlX to RAIX₂ which then reacts with remaining TiCl₄. A proposed mechanism of cyclopolymerization of conjugated dienes involves monomer activation, i.e., conversion to cation radical by one-electron transfer to catalyst cation which is itself neutralized, addition of cation end of monomer cation radical to terminal or internal unsaturation of fused cyclohexane polymer chain, one-electron transfer from “neutral” catalyst to cation on polymer chain which is then transformed to a diradical which undergoes coupling to form a cyclohexene ring. The mechanism of the “living” polymerization involves addition of catalyst-activated monomer to a “dead” polymer with a terminal cyclohexene ring and regeneration of the active catalyst.