我国高分子合成化学的发展（二）

二、聚合反应与共聚合聚合反应与共聚合反应一直是高分子合成与改性的重要内容与手段,近年仍有重要发展。下面就自由基聚合、共聚合、正负离子聚合等方面的研究概况进行简要地阐述。1.自由基聚合近年的研究主要在开发含功能基的烯类单体、新型自由基引发体系和引发机理、聚合动力学尤其高转化的聚合动力学等。李笃信等研究了 N-乙烯基咔唑在 znO 为分散     

活性阳离子聚合法合成嵌段共聚物的研究进展

在８０年代,阳离子聚合研究的一个最重要突破可能就是活性阳离子聚合。目前为止,有关活性阳离子聚合的新引发体系,新单体及合成应用等方面已取得巨大进展,本综述主要介绍利用活性阳离子聚合合成二、三元嵌段和多元嵌段共聚物的研究成果。     

中国高分子工业技术进展

介绍了“十五”期间国内合成树脂、合成纤维、合成橡胶等高分子材料生产技术的新进展.聚合工艺技术开发方面,大型化的聚丙烯、聚乙烯、聚酯、顺丁橡胶、SBS热塑性弹性体、溶聚丁苯橡胶、丁基橡胶等高分子聚合成套工艺技术相继开发成功,建成了国产化的生产装置.纺丝成套工艺技术开发方面,大容量涤纶短纤、腈纶生产技术亦取得重要进展.合成材料新产品开发方面,合成树脂专用料比例、合成纤维差别化率和合成橡胶新产品比例均有了明显提高.化工新材料方面,在非通用合成树脂,如增粘PET、环氧树脂、聚氨脂,工程塑料,如尼龙6、PBT,以及高性能纤维,如超高分子量聚乙烯纤维、PBO纤维的合成工艺技术开发与新产品开发方面均取得了重要的进展.     

引发转移终止剂技术合成含有聚异戊二烯链段的三嵌段共聚物

含聚异戊二烯 (ＰＩＰ)链段的嵌段共聚物有着广泛的应用[1～ 3 ] ,有关它的合成、性能表征及应用方面的研究一直是学术及工业界的研究热点 .传统上 ,含有ＰＩＰ链段的嵌段共聚物用活性负离子聚合的方法来合成 ,例如 :聚苯乙烯 聚异戊二烯嵌段共聚物[3 ,4 ] .这是由聚合物增长链端的特殊活性所决定的 ,采用活性负离子聚合方法 ,不但能很好地控制共聚物的分子量和分子量分布 ,而且能控制共聚物中各组分的比例 .但是 ,负离子聚合通常需在较苛刻的条件下进行 ,如低温高真空、高纯度的单体和溶剂 ,而且能用于负离子聚合的单体也有限 .相对而言 ,…     

P-配合物对异戊二烯负离子聚合中3,4结构影响的研究

在四氢呋喃(THF)与环己烷的混合溶剂中,以正丁基锂(n-BuLi)为引发剂,选取P配合物(Pcomplex)为调节剂,实现了异戊二烯(Ip)的负离子可控聚合,得到了高3,4结构率的聚异戊二烯(PI)(78.76%).采用1H-NMR对聚合物的结构进行了表征和分析.证实了由n-BuLi引发的负离子聚合,单体插入离子对之间参与聚合的速率及聚合结构取决于正负离子对之间的尺度,该尺度与单体插入所需求的尺度相当时,插入聚合速率最快,最容易.对Ip而言,单体插入离子对之间聚合形成3,4-PI时需求的尺度最小.Pcomplex由于其同时含有与Li+同源的锂原子以及空间位阻较大的苯、萘、蒽等基团,可通过改变活性种正负离子对之间的通道尺度,有效地促进3,4聚合反应,抑制1,2和1,4聚合反应,因而有效提高了PI 3,4结构率,使得Ip的聚合变得可控.相反,升高温度可以增加正负离子对之间的尺度,使得3,4聚合结构含量减少,1,4聚合结构含量增加,但温度越高,反式含量越多.     

溴化锌催化MMA基团转移聚合的研究

<正> 基团转移聚合(GTP)是Webster等首先发现的一种新型的聚合方法。最常用的引发剂为甲基三甲基硅烷基二甲乙烯酮缩醛(MTS)。催化剂有负离子型(如HF_2~-,CN~-等)和Lewis酸型。Bandermann和Mai研究了甲基丙烯酸甲酯(MMA)的负离子催化剂的GTP动学。Hertler和Sogah报道了Lewis酸催化剂的聚合反     

我国丁腈橡胶产业发展现状及未来发展趋势

概述了全球丁腈橡胶(NBR)的产能等状况,分析了我国NBR的产能、产量及消费现状,介绍了我国主要NBR生产厂家的产品结构和价格变化等情况。从环保型NBR开发、三元共聚NBR、氢化丁腈橡胶(HNBR)产品开发、乳液聚合动力学基础研究、NBR在线监测技术发展及国内NBR在关键技术进步、聚合工艺改进和新产品开发等几个方面介绍了国内外NBR生产技术的最新进展,并展望了我国未来NBR的市场及技术发展趋势。紧密联系市场,优化聚合反应配方,改进生产工艺,提高过程控制水平,研发高性能NBR的新牌号,绿色环保化生产及提高产品服务质量是增强NBR产品市场竞争力的重要举措。     

氧负离子聚合在超支化聚合物合成中的应用

近年来,氧负离子聚合得到较快发展,单体种类已经由酯基的β位上含有供电性杂原子的甲基丙烯酸酯类扩展到环氧类、甲基丙烯酸羟酯类单体.氧负离子引发这两类单体聚合,可以得到新型结构的超支化聚合物.对氧负离子引发合成超支化聚合物的机理及其应用进行了综述.     

手性乙烯基二联苯单体的合成与螺旋选择性聚合反应

设计、合成了一系列含有手性烷氧基末端的乙烯基二联苯单体,进行了普通自由基、原子转移自由基以及负离子聚合反应.所有单体中,只有手性烷氧基苯基位于乙烯基邻位的聚合物的比旋光度与其单体相比有比较大的区别,且在对应于其侧基的紫外吸收处呈现明显不同于单体的Cotton效应,说明可能形成了某一方向占优的螺旋构象.在所研究范围内,聚合条件和聚合物分子量对聚合物的旋光度没有明显的影响.比较负离子聚合和自由基聚合所获得聚合物的比旋光度发现,负离子聚合有利于增加聚合物螺旋链构象的完整性.切除能形成螺旋链的聚合物侧基上的手性烷氧基,所得到的聚合物虽然不含手性原子但依然表现出光学活性,说明其具有一定的手性记忆效应.     

通过在线~7Li-NMR谱对负离子聚合见解的进一步验证

通过对正丁基锂(n-BuLi)/四氢呋喃(THF)引发α-甲基苯乙烯(mSt)负离子本体聚合,验证了n-BuLi缔合体可以引发聚合,形成超分子团聚体,然后在进一步聚合过程中超分子解离.证实了先前提出的负离子聚合的引发机理.通过7Li-NMR对聚合过程的在线检测,进一步证实了mSt在氘代苯为溶剂,THF为调节剂下的负离子聚合以及异戊二烯在非极性条件下的溶液聚合都存在引发剂多元缔合体向二元缔合体转变.研究还发现,少量THF可能使n-BuLi的六元缔合结构2～3个进一步串联起来,但先于六元缔合结构解离.此外,THF与n-BuLi作用,随着n-BuLi/THF的摩尔比从1∶1到1∶5的变化,可以使n-BuLi的巨大缔合体解离并向六元缔合体转变.     

Anionic High Impact Polystyrene: A New Process for Low Residual and Low Cost HIPS

BASF has developed a new process for the manufacturing of High Impact Polystyrene (HIPS) via an anionic route: the so-called A-HIPS process. The driving forces were the development of a product with a low content of residuals and improved cost performance compared to the radical state of the art HIPS. The production of A-HIPS includes the synthesis of the rubber, a styrene-butadiene block copolymer. To overcome the main challenges of anionic polymerization such as reactivity control, solvent purity and initiator costs, BASF has developed its own proprietary technology, the Retarded Anionic Polymerization (R.A.P.) which allows styrene polymerization to 100% conversion under similar reaction conditions as the radical polymerization. A new low cost anionic initiator system (BuLi-free), based on sodium hydride and triethylaluminum, has been developed for perfect reactivity control over a broad temperature and concentration range even up to bulk conditions.     

Addition polymerization of 1,1-dimesitylneopentylgermene: synthesis of a polygermene

A new polymer with an alternating germanium-carbon backbone has been synthesized from 1,1-dimesitylneopentylgermene via addition polymerization using an anionic initiator.     

Kinetics and mechanism of the anionic polymerization of acrylamide monomers

The thermodynamics, kinetics, and mechanism of the anionic polymerization of a number of acrylamide monomers has been studied with the use of isothermal and scanning calorimetry, liquid chromatography, ¹H NMR and IR spectroscopy, mass spectrometry, and chemical analysis of functional groups. It has been demonstrated that the polymerization system shows the living character and the interchain exchange reactions are absent. It has been shown that N,N-diethanolacrylamide and N,N-diethanol(meth)acrylamide are uninvolved in anionic polymerization. The causes of this phenomenon have been ascertained. The products of the anionic polymerization of acrylamides are hyperbranched copolymers containing heterochain and carbochain fragments. Macromolecules contain end amide and acrylamide groups; in some macromolecules, end tert-butoxide groups of the used polymerization initiator are detected. For the products of the anionic polymerization of the acrylamide monomers under study, the temperatures of glass transition and melting have been measured.     

Surfactant Mediated Cationic and Anionic Suspension Polymerization of PEG-Based Resins in Silicon Oil: Beaded SPOCC 1500 and POEPOP 1500

A novel surfactant has been synthesized for use in cationic and anionic ring-opening suspension polymerization of PEG-based macromonomers in silicon oil. A polymer of acrylate esters containing pentamethyldisiloxane and PEG was prepared by radical polymerization. The surfactant can stabilize an emulsion of PEG-based macromonomers, initiator, and solvent in silicon oil such that polymer beads are obtained by ring-opening polymerization, initiated either by a Lewis acid (cationic ring opening) or potassium tert-butoxide (anionic ring opening). The average bead size could be controlled by varying the stirring rate and the amount of surfactant and solvent. The surfactant does not interfere with the polymerization and can be removed together with residual silicon oil by a simple washing procedure.     

Ionic polymerization in aqueous emulsion

A kinetic study of the anionic polymerization of octamethylcyclotetrasiloxane (D₄) in aqueous emulsion has been carried out in the presence of ionic additives. The rate of polymerization of several cyclosiloxanes has been compared, leading to additional evidence for an interfacial mechanism of polymerization. The emulsion process has been applied to the cationic polymerization of D₄ and of tetramethylcyclotetrasiloxane (D^H₄) initiated by dodecylbenzenesulfonic acid. Very efficient for the synthesis of linear polymethylhydrogenosiloxanes (PMHS), these conditions did not seem suitable for the polymerization of D₄. The extension of the process to other heterocyclic monomers is discussed through the anionic polymerization of phenylglycidylether.     

Anionic synthesis of well-defined polymer blends by controlled chain-transfer reactions

The scope and limitations of controlled chain transfer reactions in living anionic polymerization have been investigated. In contrast to the random nature of normal chain transfer reactions, this procedure first effects controlled living anionic polymerization followed by addition of a stoichiometric amount of suitable chain transfer agent when the monomer has been completely consumed. The resulting anionic species is then used to initiated polymerization of a second monomer charge with the same monomer or with a different monomer. A variety of hydrocarbon acids and amine compounds with pKa values in the range of 30–40 have been evaluated as chain transfer agents in the presence and absence of coordinating ligands. Efficient chain transfer to poly(styryl)lithium has been observed using 1,1-diphenylpropane. Reinitiation efficiency to both styrene and butadiene monomer was quantitative and controlled blends of different molecular weight polystyrenes or blends of polystyrene with polybutadiene have been prepared. The use of these chain transfer reactions to prepare functionalized polymers has also been investigated.     

Recent achievements in anionic polymerization of (meth)acrylates

The constant progress of the anionic polymerization of (meth)acrylates is discussed from both the fundamental and practical points of view. A special attention is paid to the improved macromolecular engineering of (meth)acrylate‐based (co)polymers. The resulting most important materials and the scaling‐up process needed for their production are also emphasized. The recent developments witness for the healthy state of the anionic polymerization of these polar monomers. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1–10, 1999     

Die lebende anionische Polymerisation

Sixty years ago Michael Szwarc discovered the living anionic polymerization. Despite the stringent synthetic requirements it has become a key method to synthesize well‐defined polymers and complex polymer architectures. Many new polymerization methods were inspired by the living anionic polymerization. Tailor‐made block copolymers are used on large scale in a large variety of industrial applications ranging from packaging to electronic devices and nanomedicine.     

Modeling of Anionic Polymerization of Isoprene in an Industrial Reactor

One of the most important reasons for modeling polymerization processes is to provide a tool for estimating the risks of runaway reactions in polymer industry. This is especially important for batch processes, such as anionic polymerization of isoprene or butadiene. This work presents a theoretical and experimental research of the anionic polymerization of isoprene using cyclohexane as solvent and n‐butyllithium as initiator. In the first part, a phenomenological kinetic expression is obtained that describes the anionic polymerization of isoprene initiated by n‐butyllithium in cyclohexane. In the second, the mass and energy balance equations are solved to model the anionic polymerization of isoprene in a quasi‐adiabatic batch reactor. Adjustment of reactor parameters is made using the data obtained from a laboratory reactor. The proposed model predicts adequately the obtained temperature, pressure, and conversion profiles from this set of experiments. Finally, a mathematical model is developed to predict the behavior for the anionic polymerization of isoprene in an industrial reactor.     

Kinetics and mechanisms in anionic ring-opening polymerization

Recent advances in the anionic ring-opening polymerization (AROP), including covalent (pseudoanionic) polymerization, are reviewed. Thermodynamics, kinetics, and mechanisms of AROP are discussed, covering mostly polymerization of oxiranes, lactones and cyclic siloxanes as monomers. The following general problems of AROP are discussed: anionic polymerizability, thermodynamics - particularly of the monomers exhibiting low ring strain, chemistry of initiation, structures and reactivity of active species. New phenomena, particularly polymerization with reversibly aggregating species are analyzed in more detail. Chain transfer to polymer - the major side reaction - is analyzed quantitatively, by introducing the selectivity parameter β, expressed by the ratio k_p/k_tr. This parameter has been determined for the anionic and pseudoanionic polymerization of ϵ-caprolactone.