STUDIES ON THE INITIATION MECHANISM OF ORGANIC PEROXIDE AND N-METHACRYLOYLOXYETHYL-N-METHYL ANILINE IN METHYL METHACRYLATE POLYMERIZATION

The initiation mechanism of methyl methacrylate (MMA) polymerization by organic peroxide and polymerizable aromatic tertiary amine such as N-methacryloyloxyethyl-N-methyl aniline (MEMA) binary system has been studied. The kinetics of polymerization of MMA and the ESR spectra of organic peroxide/MEMA system were determined. Based on the ESR study and the end-group analysis by UV spectra of the polymer formed, the initiation mechanism is proposed.     

有机过氧化物与N,N-二(2-羟烷基)对甲苯胺体系引发烯类聚合及其机理的研究

研究了有机过氧化物BPO,LPO分别与N,N-二(2-羟烷基)对甲苯胺DHET,DHPT组成的体系引发MMA的聚合。测定其聚合速度R_p,聚合表观活化能,聚合速度方程,聚合放热过程的温度与时间的关系。用自旋捕捉和ESR波谱技术,测定了上述体系反应产生的自由基中间体,同时通过聚合物端基分析证实DHET,DHPT组份产生的自由基能引发单体聚合。依据实验结果提出了这类体系的引发机理。     

THE KINETICS OF METHYL METHACRYLATE POLYMERIZATION INITIATED BY THE VOLATILE PRODUCTS OF A METHYL METHACRYLATE PLASMA

It is found that the volatile products of methyl methacrylate plasma can very actively initiate the polymerization of the monomer to produce ultrahigh molecular weight polymers. This polymerization of MMA occurs by a livlng free radical mechanism with instantaneous initiation and monomer transfer.     

质子捕捉技术在阳离子聚合中的应用

本文介绍了质子捕技术在阳离子聚合中的应用最新研究工作进展。对质子捕捉剂在阳离子聚合反应机理研究中的应用以及质子捕捉剂在活性阳郭聚合引发体系中的作用和功能作了详尽的讨论。     

双吡唑亚胺镍/甲基铝氧烷催化降冰片烯的聚合

合成了两种双吡唑亚胺镍配合物: 双-N-(苯基-1-3,5-二甲基吡唑基亚甲基)苯基亚胺二溴化镍(Cat.1)和双-4-甲氧基-N-(苯基-1-3,5-二甲基吡唑基亚甲基)苯基亚胺二溴化镍(Cat.2). 研究了Cat.1/MAO和Cat.2/MAO催化体系对降冰片烯(NBE)单体聚合的催化性能, 考察了各种聚合条件, 如温度、Al/Ni摩尔比及催化剂浓度对降冰片烯的催化效率、单体转化率、聚合物分子量及分子量分布的影响. 研究结果表明, Cat.1/MAO和Cat.2/MAO催化体系对降冰片烯聚合具有较高的催化效率, 可达到105 g PNBE/(mol Ni)数量级, 所得聚降冰片烯(PNBE)的重均分子量在105以上, 分子量分布指数在2左右. 聚合产物的1H NMR和FTIR谱分析结果表明, 该聚合反应是以单体的乙烯基加成聚合机理进行的.     

二苯基碘鎓盐引发氨酯型乙烯基醚热聚合

合成了2种固态氨酯型乙烯基醚PUE1和PUE2,并对其结构和性能进行了表征.研究发现,二芳基碘六氟磷酸盐(PI810)能引发PUE1和PUE2发生阳离子热聚合,热聚合温度远低于PI810的纯态热分解温度,且聚合转化率很高.初步认为热聚合机理是富电子的乙烯基醚双键和缺电子的二苯基碘盐阳离子之间形成中间态电荷转移复合物,降低了二苯基碘盐的热分解温度,进而生成引发活性种乙烯基醚阳离子自由基或质子酸,引发乙烯基醚的阳离子聚合反应.     

微乳液聚合制备透明丙烯酸酯多孔共聚物

多孔聚丙烯酸酯;引发;微乳液聚合制备透明丙烯酸酯多孔共聚物     

铈离子与氨基甲酸酯类化合物引发丙烯酰胺聚合的研究

本文对铈离子与苯基氨基甲酸酯类化合物在H_2O-CH_3CN(3∶1,V/V)及H_2O-HCONH_2(1∶2,V/V)两种介质中引发丙烯酰胺的聚合进行了研究。考察了不同结构的苯基氨基甲酸酯对聚合的影响。苯基氨基甲酸酯类化合物对铈离子引发聚合均有促进作用,其中对-甲苯基氨基甲酸酯的促进作用最为显著。测定了聚合反应表现活化能及聚合动力学方程,并提出了聚合反应机理。     

阳离子聚合的进展

首先介绍了阳离子聚合的简史,由于阳离子高活性的特点使其发展较慢,阳离子聚合研究的突破来自对引发反应的深入理解,而近代阳离子聚合的要点则在于使链引发、链增长和链终止成为可控。阳离子聚合的进展密切与大分子工程相关。本文对活性阳郭聚合做了较详细的讨论。并举遥爪聚人事物及嵌段聚合物的研究成就。最后,提出了阳离子聚合是发展中的问题供参考。     

有机过氧化物与N-甲基-N-2-羟乙基苯胺引发体系的研究

测定了有机过氧化物与N-甲基-N-2-羟乙基苯胺(HMA)体系引发MMA聚合的动力学方程和聚合表现活化能。由过氧化物/HMA/MNP的ESR波谱证实芳叔胺HMA中,与氮原子相连的亚甲基的氢被摘去形成相应的碳自由基,它能引发单体聚合成为聚合物的端基。这也由聚合物的UV光谱所证实,由实验结果提出这类体系的引发机理。     

THE EFFECTS OF MONOMER STRUCTURE OF CYCLIC KETENE ACETALS ON THE BEHAVIOR OF CONTROLLED RADICAL RING-OPENING POLYMERIZATION

Polymerization of three cyclic ketene acetals: i.e., 5,6-benzo-2-methylene-1,3-dioxepane (BMDO), 2-methylene-4-phenyl-1,3-dioxolane (MPDO) and 4, 7-dimethyl-2-methylene-1, 3-dioxepane(DMMDO) were carried out in the presence ofethyl α-bromobutyrate/CuBr/2, 2'-bipyridine respectively. The structures of poly(BMDO), poly(MPDO) and poly(DMMDO)were characterized by ~1H and ~(13)C-NMR spectra. The effects of monomer structure on the behavior of atom transfer freeradical ring-opening polymerization were investigated and the mechanism of controlled free radical ring-openingpolymerization was discussed.     

光调控的活性自由基聚合的研究新进展

从引发和催化两个方面概述了光辐照在活性自由基聚合(LRP)中的应用,从机理上详细地分析了光辐照对氮氧调控自由基聚合(NMP)、原子转移自由基聚合(ATRP)、可逆加成-断裂链转移自由基聚合(RAFT)以及有机钴催化的可控自由基聚合反应(CMRP)的影响。与传统自由基聚合相比,光调控的活性自由基聚合方法可在温和的条件下生成自由基,能够克服传统LRP的一些缺陷,如降低催化反应活化能、提高聚合物末端官能度等。同时,本文对光调控反应的进一步应用以及新方法的产生也进行了展望。     

二苯基碘鎓盐引发乙烯基醚热聚合研究

合成了一种液态聚氨酯乙烯基醚预聚物 (PUE)并对其进行了表征 .研究发现二苯基碘六氟磷酸盐(PI810 )能够引发PUE和三缩乙二醇二乙烯基醚 (DVE 3)进行阳离子热聚合 ,热聚合温度远低于PI810的纯态热分解温度 ,且聚合转化率较高 .热聚合的机理初步认为是电子转移机理 .研究了乙烯基醚化合物、环氧树脂、二苯基碘六氟磷酸盐混合体系的热聚合 .     

Controlled/living polymerization of MMA promoted by heterogeneous initiation system (EPN‐X–CuX–bpy)

The polymerization of methyl methacrylate (MMA) promoted by heterogeneous initiation system (ethyl‐2‐halopropionate (EPN‐X)–CuX–2,2′‐bipyridyl (bpy), where X = Br or Cl) is studied in detail. The results show that ethyl‐2‐bromopropionate (EPN‐Br) is an efficient initiator as expected, and that CuCl–bpy, instead of CuBr–bpy, is a better catalyst for the controlled polymerization of MMA. The solvents with a high value of dielectric constant (ε) will lead to fast initiation and narrow molecular weight distribution (MWD). As a result, the controlled, living polymerization of MMA with EPN‐Br–CuCl–bpy can be got in ethyl acetate (EAc) at 100°C and in acetonitrile at 80°C. All results suggest that the initiation reaction is a controlling step in the controlled polymerization of MMA. The relationship between the UV spectra of CuCl–bpy and the performances of the polymerization in EAc or acetonitrile suggest that the formation of bis‐bpy complex, [Cubpy₂]X⁻, will lead to fast initiation and good control of the polymerization. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1255–1263, 1999     

过氧化二碳酸酯和N N-二羟烷基对甲苯胺体系引发甲基丙烯酸甲酯聚合

本文以过氧化二碳酸酯BPPD和芳叔胺DHET、DHPT、DMT、DMA组成的引发体系进行MMA聚合的研究。测定了聚合速率R_p,发现添加DHET、DHPT能促进MMA的聚合,缩短诱导期,提高R_p,其效果要比DMT、DMA为好。测定了E₃和聚合速率方程。由ESR谱和端基分析证实DHET、DHPT芳胺组分产生的自由基能引发单体聚合。     

二(叔丁基环戊二烯基)钕甲基配合物催化ε-己内酯开环聚合

二（叔丁基环戊二烯基）钕甲基配合物催化ε 己内酯开环聚合罗云杰姚英明沈琪（苏州大学化学化工学院苏州２１５００６）关键词开环聚合，ε 己内酯，茂基稀土甲基配合物聚ε 己内酯（Ｐｏｌｙｃａｐｒｏｌａｃｔｏｎｅ，ＰＣＬ）是一种生物降解材料，有良好的相...     

Polymerization of oil (styrene and methylmethacrylate)-in-water microemulsions

 The polymerization of styrene-in-water and methylmeth-acrylate-in-water microemulsions stabilized by nonionic surfactants was investigated using different initiation techniques. Thermally induced initiation was carried out using potassium persulfate (water soluble) and azobisiso-butyronitrile (AIBN) (oil soluble) at 60° and 50°C, respectively. When the monomer concentration was kept below a certain limit, the particle size of the nanolatex was similar to the droplet size of the microemulsion precursor. At higher monomer concentrations, the latex produced was significantly larger than the microemulsion droplets, as a result of the possible coalescence of the microemulsion droplets during polymerization. By using chemically induced polymerization (hydrogen peroxide+ascorbic acid) at temperatures below the cloud point temperature of the microemulsion or by photochemically induced initiation at room temperature, it was possible to obtain nanolatex particles with similar size to the droplets up to 10% monomer content. In all cases, the particle size was determined using photon correlation spectroscopy (PCS). Electron micrographs of the microlatex particles were taken and these confirmed the measurements obtained by PCS. The molecular weight of the polymers produced was determined by gel permeation chromatography. The average number of polymer molecules per particle was calculated. It was shown in some cases that the nanolatex contained one polymer chain per particle. A mechanism was suggested for polymerization and particle growth. Received: 29 May 1997 Accepted: 28 May 1998     

二(2,6-二叔丁基-4-个甲基苯氧基)钐催化丙交酯开环聚合

聚丙交酯（PLA）可以生物降解，产物无毒，可用于外科手术的缝合线、人造器官以及药物缓释等方面，因此引起了人们的广泛注意．丙交酯的开环聚合是合成聚丙交酯的一种方便方法，所用的催化剂主要是主族及副族金属的配合物，如双金属氧桥配合物［‘j，烷基金属有机化合物［‘j，异丙氧基铝［’‘以及叶琳铝「“等．最近，关于三价烷氧基稀土化合物作为单组份催化剂催化丙交酯开环聚会已有报道［’·’‘．我们发现两价芳氧基稀土化合物（ArO）。Sin（THF）。（ArO一2，已二叔丁基一个甲基苯氧基）也可以有效地催化丙文酯的开环聚合．本…     

直链型双官能度引发剂2,5-二甲基-2,5-二(2-乙基己酰基过氧)己烷(DMDEHPH)引发苯乙烯聚合实验与仿真研究

从基于聚合机理的基元反应和物料衡算出发, 考虑聚合过程中的体积收缩和热引发, 详细推导了直链型双官能度引发剂引发苯乙烯聚合的动力学模型, 考虑凝胶、玻璃化和笼蔽效应等对各速率常数和物性参数的影响, 利用基于自由体积理论的扩散控制速率参数和矩方法求解各物种浓度、聚合速率、分子量及多分散度的表达式. 利用模型计算了不同温度和引发剂[2,5-二甲基-2,5-二(2-乙基己酰基过氧)己烷(DMDEHPH)]浓度下的转化率、分子量和多分散度, 均与实验结果相符. 模型还可计算各自由基、含过氧键和双端终止聚合物浓度, 结果表明浓度对转化率曲线中均有一峰值, 双自由基浓度比单自由基浓度低几个数量级, 不同聚合物浓度则仅差几倍. 不同引发剂浓度下同物种浓度曲线无交点, 且引发剂浓度越大物种浓度越高; 不同温度下的曲线有交点, 凝胶效应阶段温度越低浓度越大, 凝胶效应之前和之后则温度越低浓度越小.     

Living Polymerization of Lactide Using Titanium Alkoxide Catalysts

Several titanium isopropoxides have facilitated the ring opening polymerization of l-lactide (LA) and rac-lactide in toluene solution at various polymerization temperatures via a coordination insertion mechanism. Depending on catalysts, the controlled/living poly(l-lactide), or the heterotactic-biased poly(rac-lactide) were obtained. The stereochemical microstructure of polylactide (PLA) was determined from homonuclear decoupled ¹H NMR spectral studies. Such spectra of PLA derived from rac-LA featured the characteristic five-methine resonance pattern, whereas corresponding spectra derived from l-LA exhibited only one methine peak.