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

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孙俊全（浙江大学高分子科学与工程系杭州３１００２７）（中国科学院长春应化所稀土化学与物理开放实验室长春１３００２２）关键词聚合反应，配位聚合，稀土催化剂，甲基丙烯酸甲酯，...     

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.     

Ln（acac）3—BuMgCl催化甲基丙烯酸甲酯聚合

开发了催化甲基丙烯酸甲酯聚合的一类新型催化剂，由稀土乙酰基丙酮配合物Ｌｎ（ａｃａｃ）３和格氏试剂ＢｕＭｇＣｌ组成．研究了不同稀土元素、催化剂陈化时间和温度、溶剂、ＣＣｌ４添加剂、聚合时间和温度的影响．结果表明，在石油醚中单体聚合转化率和聚合物相对分子质量高于芳烃和其它极性溶剂，过量ＢｕＭｇＣｌ可能起链转移作用，降低温度可提高聚合物的间同含量．     

Atom transfer radical polymerization of methyl methacrylate via reversibly supported catalysts on silica gel via self‐assembly

A reversible catalyst immobilization system via self‐assembly of hydrogen bonding between thymine anchored on silica gel support and 2,6‐diaminopyridine functionalized with a catalyst (copper bromide‐N,N,N′,N′‐tetraethyldiethylenetriamine (TEDETA) complex) was developed for the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). At elevated temperatures, the hydrogen bonding disassociated and released the catalyst as free small molecules for catalysis, which effectively mediated a living polymerization of MMA, producing PMMA with controlled molecular weight and narrow molecular weight distribution (<1.3). At room temperature, the catalyst assembled on the silica gel support by hydrogen bonding, and thus could be recovered and reused for a second run of ATRP. The recovered catalyst still mediated a living polymerization of MMA with reduced activity (54–64%), but had much improved control of the polymerization. The resulting PMMA had molecular weights very close to theoretical vales. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 22–30, 2004     

The Polymerization of Methyl Methacrylate with a New Nd(O—i-Pr)_3—AI(i-Bu)_3Catalyst System

ＴｈｅＰｏｌｙｍｅｒｉｚａｔｉｏｎｏｆＭｅｔｈｙｌＭｅｔｈａｃｒｙｌａｔｅｗｉｔｈａＮｅｗＮｄ（Ｏ—ｉ┐Ｐｒ）３—ＡＩ（ｉ┐Ｂｕ）３ＣａｔａｌｙｓｔＳｙｓｔｅｍ＊ＳＵＮＪｕｎ－ｑｕａｎ（Ｄｅｐｔ．ｏｆＰｏｌｙｍ．Ｓｃｉ．ａｎｄＥｎｇｉｎｅｒｉｎｇ,Ｚ...     

Synthesis of Poly (methyl methacrylate)/Zinc Oxide Nanocomposite with Core-Shell Morphology by Atom Transfer Radical Polymerization

A method to prepare zinc oxide (ZnO) nanoparticles with a covalently bonded poly(methyl methacrylate) (PMMA) shell by surface initiated atom transfer radical polymerization (ATRP) was reported. First, the initiator for ATRP was covalently bonded onto the surface of zinc oxide nanoparticles through our novel method. Firstly, the surface of ZnO nanoparticle was treated with 3-aminopropyl triethoxysilane, a silane coupling agent, and then this functionalization nanoparticle was reacted with α-chloro phenyl acetyl chloride to prepare atom transfer radical polymerization macroinitiator. The metal-catalyzed radical polymerization of MMA with ZnOmacroinitiator was performed using a copper catalyst system to give the ZnO-based nanoparticles hybrids linking PMMA segments (poly (methyl methacrylate)/zinc oxide nanocomposite). These hybrid nanoparticles had an exceptionally good dispersability in organic solvents and were subjected to detailed characterization using FTIR, TEM and TGA and DSC analyzed.     

Atom transfer radical polymerization of methyl methacrylate catalyzed by ion exchange resin immobilized Co(II) hybrid catalyst

Ion exchange resin immobilized Co(II) catalyst with a small amount of soluble CuCl₂/Me₆TREN catalyst was successfully applied to atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in DMF. Using this catalyst, a high conversion of MMA (>90%) was achieved. And poly(methyl methacrylate) (PMMA) with predicted molecular weight and narrow molecular weight distribution (M_w/M_n = 1.09–1.42) was obtained. The immobilized catalyst can be easily separated from the polymerization system by simple centrifugation after polymerization, resulting in the concentration of transition metal residues in polymer product was as low as 10 ppm. Both main catalytic activity and good controllability over the polymerization were retained by the recycled catalyst without any regeneration process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1416–1426, 2008     

二氧化硅负载[C5Me5]2SmMe(THF)引发甲基丙烯酸甲酯聚合

近年来 ,有许多文献报道茂金属催化剂的负载化及其在烯烃聚合中的应用 ,这对发展新型茂金属催化剂和开发新型高分子材料有重要意义 [1,2 ] .我们 [3]曾报道壳聚糖负载稀土催化剂用于甲基丙烯酸甲酯的配位聚合有优良性能 .以五甲基环戊二烯为配体的有机稀土配合物 ,如 [Sm H( C5Me5) ]2 ,[C5Me5]Ln Me( THF) ( Ln=Sm,Yb)等在甲苯中单组分引发甲基丙烯酸甲酯聚合及内酯开环聚合具有许多优异性能[4 ,5] ,但是经负载化的该类催化剂的聚合性能尚未见报道 .本文报道将 [C5Me5]2 Sm Me·( THF)负载于二氧化硅 ,引发甲基丙烯酸甲酯聚合的结…     

Polymerization of methyl methacrylate with ethylene bridged heterodinuclear metallocene of samarium and titanium

A novel heterodinuclear catalyst, ethylene bridged samarocene and titanocene chloride (Sm-Ti), was used both as a single component catalyst (cat.) and also by activation with triisobutyl aluminum (TIBA) to polymerize methyl methacrylate (MMA). The binary catalyst demonstrated higher activity than the single component, but the molecular weight of the resultant PMMA is lower. Ultrahigh molecular weight PMMA (1.5×10⁶) was obtained at an attractive conversion (87%) without any cocatalyst. The effects of polymerization parameters, such as temperature, time, molar ratios of Al(i-Bu)₃/cat. and MMA/cat., were studied in detail. The results showed that the catalytic activity had a rather different dependence on the polymerization temperature with/without TIBA. High molecular weight PMMA was much more easily prepared in a bulk system than in toluene solution. The polymer yielded with about 65% syndiotacticity by 1H NMR and 75% by IR spectroscopy, but its stereoregularity did not change too much with polymerization temperature and the concentration of TIBA.     

Polymerization of MMA by oscillating zirconocene catalysts, diastereomeric zirconocene mixtures, and diastereospecific metallocene pairs

Characteristics of methyl methacrylate (MMA) polymerization using oscillating zirconocene catalysts, (2-Ph-Ind)₂ZrX₂ (X = Cl, 1; X = Me, 2), mixtures of rac- and meso-zirconocene diastereomers, (SBI)ZrMe₂ [3, SBI = Me₂Si(Ind)₂] and (EBI)ZrMe₂ [4, EBI = C₂H₄(Ind)₂], as well as diastereospecific metallocene pairs, rac-4/Cp₂ZrMe₂ (5) and rac-4/CGCTiMe₂ [6, CGC = Me₂Si(Me₄C₅)(t-BuN)], are reported. MMA polymerization using the chloride catalyst precursor 1 activated with a large excess of the modified methyl aluminoxane is sluggish, uncontrolled, and produces atactic PMMA. On the other hand, the polymerization by a 2/1 ratio of 2/B(C₆F₅)₃ or 2/Ph₃CB(C₆F₅)₄ is controlled and produces syndiotactic PMMA. Mixtures of diastereomeric ansa-zirconocenes 3 or 4 containing various rac/meso ratios, when activated with B(C₆F₅)₃, yield bimodal PMMA; this behavior is attributed to the meso-diastereomer that, in its pure form, affords bimodal, syndio-rich atactic PMMA. For MMA polymerization using diastereospecific metallocene pairs, rac-4/5 and rac-4/6, the isospecific catalyst site dominates the polymerization events under the conditions employed in this study, and the aspecific and syndiospecific sites are largely nonproductive, thereby forming only highly isotactic PMMA.     

Synthesis and morphology of polyethylene‐block‐poly(methyl methacrylate) through the combination of metallocene catalysis with living radical polymerization

Polyethylene‐block‐poly(methyl methacrylate) (PE‐b‐PMMA) was successfully synthesized through the combination of metallocene catalysis with living radical polymerization. Terminally hydroxylated polyethylene, prepared by ethylene/allyl alcohol copolymerization with a specific zirconium metallocene/methylaluminoxane/triethylaluminum catalyst system, was treated with 2‐bromoisobutyryl bromide to produce terminally esterified polyethylene (PE‐Br). With the resulting PE‐Br as an initiator for transition‐metal‐mediated living radical polymerization, methyl methacrylate polymerization was subsequently performed with CuBr or RuCl₂(PPh₃)₃ as a catalyst. Then, PE‐b‐PMMA block copolymers of different poly(methyl methacrylate) (PMMA) contents were prepared. Transmission electron microscopy of the obtained block copolymers revealed unique morphological features that depended on the content of the PMMA segment. The block copolymer possessing 75 wt % PMMA contained 50–100‐nm spherical polyethylene lamellae uniformly dispersed in the PMMA matrix. Moreover, the PE‐b‐PMMA block copolymers effectively compatibilized homopolyethylene and homo‐PMMA at a nanometer level. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 3965–3973, 2003     

Atom Transfer Radical Polymerization of MMA Initiated by 2‐(4‐chloromethyl‐phenyl)‐benzoxazole and Fluorescent Property of PMMA

Atom transfer radical polymerization (ATRP) of MMA was conducted using 2‐(4‐chloromethyl‐phenyl)‐benzoxazole as initiator, CuCl as catalyst, and PMDETA as ligand. The results show that the polymerization is a first order reaction with respect to monomer concentration. The polymerization displayed living character as evidenced by a liner increase of monomer weight with conversation and a relatively narrow distribution (Mn/Mw range from 1.30 to 1.45). The structure of PMMA was analyzed by ¹H‐NMR and proved the polymerization could be controlled to some degree. The optical property of the initiator was well preserved in the resulting PMMA, and the end‐functionalized PMMA exhibited fluorescent emission at 360 nm whether in DMF solution or in film state.     

Vinyl polymerization by lithium organocuprates

Vinyl polymerizations initiated by lithium organocuprates under several conditions were investigated. It was observed that this catalyst was effective in the polymerization of specific monomers such as α,β-unsaturated nitrile and carbonyl analogues. The rate of polymerization was rapid but retarded by the addition of pyridine, nitrobenzene, or hydroquinone. Polymerization of methyl methacrylate (MMA) with lithium di-n-butylcuprate as initiator produces predominantly isotactic poly(methyl methacrylate) (PMMA) in toluene. The overall activation energy was estimated as 3.5 kcal/mol deg. Lithium di-n-butylcuprate exerts a higher stereoregulating effect on the addition of monomers than other organolithium initiators. It is proposed that polymerization proceeds via a coordinated anionic mechanism.     

Atom transfer radical polymerization of methyl methacrylate catalyzed by cobalt catalyst system

A new catalyst system, CoCl₂/tris(2‐(dimethyl amino) ethyl)amine (Me₆ TREN), was used to catalyze the polymerization of methyl methacrylate (MMA) successfully through atom transfer radical polymerization mechanism. The control over the polymerization was not ideal, the molecular weight distribution of the resulting polymer (PMMA) was relatively broad (M_w/M_n = 1.63–1.80). To improve its controllability, a small amount of hybrid deactivator (FeBr₃/Me₆TREN or CuBr₂/Me₆TREN) was added in the cobalt catalyst system. The results showed that the level of control over the polymerization was significantly improved with the hybrid cobalt–iron (or cobalt–copper) catalyst system; the polydispersity index of the resulting polymer was reduced to a low level (M_w/M_n = 1.15–1.46). Furthermore, with the hybrid cobalt–iron catalyst, the dependence of the propagation rate on the temperature and the copolymerization of methacrylate (MA) with PMMA‐Br as macroinitiator were also investigated. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5207–5216, 2005     

新引发体系引发MMA活性自由基聚合

近年来 ,关于活性自由基聚合的研究极为活跃 ,已经发现了多种基于增长链自由基被可逆钝化形成休眠种的活性自由基聚合方法[1,2 ] .它们主要包括引发转移终止剂 ( Iniferter) ,稳定自由基聚合( SFRP) ,原子转移自由基聚合 ( ATRP) ,可逆加成 -断链链转移聚合 ( RAFT)等 .其中 ATRP因其具有可聚合单体多 ,反应条件相对缓和等优点而成为该领域的研究热点 [3～ 5] .ATRP活性自由基聚合的实现主要是在过渡金属催化剂的作用下 ,通过循环往复的碳 -卤键的活化、加成、碳 -卤键的再形成而得到最终活性的聚合物 ,引发体系由引发剂、过渡金属…     

甲基丙烯酸甲酯的反向原子转移自由基聚合反应 研究

在较低的温度(60℃)和较低的AIBN/CuCl~2/配位剂摩尔比(1:2:4)条件下,用乙腈为溶剂,实现了甲基丙烯酸甲酯(MMA)的反向原子转移自由基聚合(RATRP)。联二吡啶(bpy)为配位剂时,所合成的聚甲基丙烯酸甲酯(PMMA)的分子量分布可低至1.08。用1,10-菲咯啉(phen)代替bpy,MMA的聚合反应速率加快,但其分子量分布稍宽(1.40左右),并进一步研究了bpy和phen作为混合配位剂时对MMA反向ATRP聚合的影响。用RATRP反应所得的带有卤素端基的PMMA作为苯乙烯ATRP的大分子引发剂,成功地合成了具有预期结构的苯乙烯与甲基丙烯酸甲酯嵌段共聚物,大分子引发剂的引发效率接近于1,说明在RATRP过程中由自由基引发剂引发MMA进行一般自由基聚合反应的可能性甚微。     

单组分桥联茂基二异丙胺基钕配合物催化甲基丙烯酸甲酯聚合

催化聚合;茂稀土胺化物;单组分桥联茂基二异丙胺基钕配合物催化甲基丙烯酸甲酯聚合     

碱性离子液体催化金属调节的甲基丙烯酸甲酯的电子转移活化原子转移自由基聚合

通过电子转移活化原子转移自由基聚合（AGET ATRP）,以2-溴代异丁酸乙酯（EBiB）为引发剂、维生素C（VC）为还原剂。 以碱性离子液体1-丁基-3-甲基咪唑氢氧化盐([Bmim][OH])分别和FeCl3·6H2O、CuCl2及RuCl3形成的配合物为催化剂催化甲基丙烯酸甲酯（MMA）的本体和溶液聚合。 催化量的[Bmim][OH]即可提高聚合速率,并且得到相对分子质量分布可控的PMMA（Mw/Mn为1.20～1.40）。 研究了[Bmim][OH]的加入量对聚合速率和相对分子质量分布的影响,3种催化体系催化性质通过循环伏安曲线表征。 扩链反应证明了碱性离子液体催化甲基丙烯酸甲酯的聚合为“活性”/可控自由基聚合。 碱性离子液体良好的溶解性使其成为活性自由基聚合的良好催化剂。     

Synthesis of block copolymers by combined ultrasonic irradiation and reverse atom transfer radical polymerization processes

A two-step procedure based on ultrasonic irradiation and reverse atom transfer radical polymerization (RATRP) for the synthesis of block copolymers is described. In the first step of the procedure, a stable chlorine-end-capped polymer is formed upon the ultrasonic irradiation of poly(methyl methacrylate) (PMMA) in dry benzene in the presence of a copper chloride/2,2′-bipyridine catalyst. Heating the system to 110 °C initiates the polymerization of the second monomer, styrene, and this results in the formation of the block copolymers. The degradation behavior of PMMA under ultrasonic irradiation has also been studied. The agreement of the experimentally obtained molecular weights and theoretical molecular weights and the unimodal shapes of the gel permeation chromatography curves of the block copolymers indicate the controlled nature of the RATRP process initiated by polymeric radicals formed by sonication. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 534–540, 2004     

Synthesis and Characterization of a Diblock Copolymer of Methyl Methacrylate and Vinyl Acetate by Successive Photo‐Induced Charge Transfer Polymerization Using Ethanolamine as the Parent Compound

Communication: A diblock copolymer consisting of poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) with hydroxyl group at one end is prepared by successive charge transfer polymerization (CTP) under UV irradiation at room temperature using ethanolamine and benzophenone as a binary initiation system. The diblock copolymer PMMA‐b‐PVAc could be selectively hydrolyzed to the block copolymer of poly(methyl methacrylate) and poly(vinyl alcohol) (PVA) using sodium ethoxide as the catalyst. Both copolymers, PMMA‐b‐PVAc and PMMA‐b‐PVA, are characterized in detail by means of FTIR and ¹H NMR spectroscopy, and GPC. The effect of the solvent on CTP and the kinetics of CTP are discussed.