聚合物分子设计的原理与方法-4-20课件

1、 高聚物分子设计 (Polymer Design)内容概要： 介绍聚合物分子设计的基本概念、原理和方法，重点介绍定向聚合、嵌段聚合、接枝聚合和活性自由基聚合在高聚物分子设计中的应用主要参考书： 周其凤，胡汉杰跨世纪的高分子科学-高分子化学，化学工业出版社； （日本）高分子学会编 徐震春，岳传龙 译，朱洪法校高分子的分子设计，上海科学技术出版社； 安智珠聚合物分子设计原理，湖南科学技术出版社。分子设计的概念 分子设计一词原先由美国麻省理工学院材料科学专业的霍恩.贝尔教授在上世纪提出。 20 世纪70 年代,美国麻省理工学院霍恩贝尔教授提出了分子设计。即从分子、电子水平上,通过数据库等大量实验数据

2、,结合现代量子化学方法,通过计算机图形学技术等设计新的分子。设计的新分子或具有某种特定性能,可以是药物、材料或其他,或是一种概念、一种复合物或不具有分子意义的物质(如催化剂等)。分子设计的基本概念是为使材料适其所用,在首先了解构成材料的分子化学结构和物性之间相互关系的基础上, 再根据要求合成出具有所得物性而又有特定化学结构的物质。聚合物分子设计学说的建立 聚合物分子设计是现代高分子科学中最重要的研究方向之一，它是在高分子化学和物理学以及高分子材料科学的基础理论和实际应用研究的基础上发展起来的一门新兴的学课 它需要用所归纳和积累起来的关于高分子结构与性质、结构与合成、性能与加工各种关系个约大量数

3、据，包括从宏观性能到微观结构，从定性到定量，静态与动态等方面的理论和应用的丰富数据，以及从中找出内在的基本规律，并提出实现该种结构所需要的合成与加工方法及其条件。 用比较少的实验，准确地合成具有预定结构和指定性能的高分子化合物。聚合物分子设计是高分子科学和材料科学发展的必然趋势。 自从十九世纪中叶至二十世纪初对天然高分子的改性以及从双烯得到了合成橡胶，从酚和醛合成了酚醛树脂，并加工成塑料高分子材料发展得异常迅速 四十年代人造纤维的产量就超了当时羊毛的产量。五十年代塑料的产量先超过了铝，随后又超了钢和锌，从六十年代开始，出现芳香族聚酰胺和芳香族杂环聚合物 那么为什么迄今才提出高分子的分子设计呢?

4、其中一个原因是，高分子工业以前一直是遵循着新聚合物发现 物性研究 加工技术开发 用途开发这样一条路线发展起来的，至今已开始趋于尽头 掌握了完备的测定分子量、分子量分布的方法以及微观结构的结构分析法,就能合成出单一分散的聚合物。所需序列长度的嵌段共聚物和所需支链长度的接技共聚物等物质，就是一次结构也能使分子具有数之不尽的形态。因此，高分子的分子设计显示出无限厂阔的前景。定向聚合 又称立体有择聚合、立体选择聚合，立体对称聚合或有规立构聚合，单体形成立体规整性聚合物的聚合过程。可细分为配位聚合、离子型定向聚合和自由基型定向聚合等。 定向催化剂有Ziegler催化剂、Natta催化剂和离子型催化剂等。

5、 能进行定向聚合单体有-烯烃，二烯烃和烯类单体等，所得的聚合物称作定向聚合物。 聚合物分子中原子或原子团在空间的排布方式（构型）主要分两类：几何异构和光学异构(旋光异构)。前者由双键或环上的取代基在空间分布不同造成，有顺式和反式两种。后者由不对称碳原子或分子整体不对称引起。 该类聚合物或具有旋光性，或由于内消旋作用而不显光学活性。C*可采用R（右旋）或S（左旋）构型。根据R和S构型在链中分布可得有规立构链及无规立构链。前者包括由相同构型单元组成的 （如-R-R-R-R-或-S-S-S-S-） 全同立构聚合物或等规聚合物及构型交替的间同立构聚合物。嵌段聚合 嵌段共聚物的主链至少由两种单体单元构成

6、足够长的链段组成 ，常见的有AB,ABA,ABAB, ABC型可以用多种机理来合成嵌段共聚物1.活性阴离子聚合 这是工业上合成嵌段共聚物的常用方法，SBS就是一个例子常温下SBS反应出B段弹性体的性质，S段处于玻璃微区，起到物理交联 的作用温度上升到聚苯乙烯玻璃化温度以上，SBS具有流动性，可以模塑，因此SBS可称作热塑性弹性体，具有无需硫化的特点。 利用活性阴离子聚合的机理，还可以合成环氧丙烷-环氧乙烷嵌段共聚物，用于非离子型表面活性剂。 2.特殊引发剂 双功能自由基引发剂可以用来先后引发两种单体聚合而形成嵌段共聚物接枝聚合 接枝共聚物的性能决定于主，支链的组成和长度，以及枝链数 接枝反应的

7、首要条件是要有接枝点。各种聚合机理的引发剂都能为接枝共聚提供活性种。例如应用引发剂化学分解，光，高能辐射等。 接枝点和支链的产生方式，接枝方法大致有三类长出支链 先在某一大分子链中间形成活性点，该活性点再 引发另一单体聚合而长出支链。接枝点可由自由基，阴离 子，阳离子，配位聚合机理产生2. 嫁接支链 如果某一大分子主链带有活性侧基，另一大分子 带有活性端基，两者反应，就嫁接上支链3. 大单体共聚嫁接 PVC接枝聚合氯乙烯与聚二烯烃和二烯烃共聚物的接枝共聚物 聚丁二烯和丁二烯共聚物作为氯乙烯单体接枝聚合的对象，一度吸引过人们的注意，这主要是想利用它们的高弹性。然而这类接枝产品的多数迄今尚缺乏实际

8、意义。原因在于氯乙烯在很少量的丁二烯单体存在下就难以进行聚合 有些成就值得注意，其中包括通过接枝加入少量弹性体(二烯烃共聚物)从而大大提高PVC的韧性。由于这些弹性体的玻璃化转变温度低(-90 50)故当环境温度降低时，PVC产品仍表现出高的韧性和冲击强度。这样得到的高抗冲PVC的冲击性能要比相应的弹性体与PVC的共混物为好例如通过接枝得到的聚（丁二烯-丙烯腈）-g-氯乙烯，由于含有接枝物，使产物比相应的共混物在拉伸冲击强度上高出不少PVC与丁腈橡胶接枝共聚物及共混物的拉伸冲击强度 一些公司已向市场推出用丁二烯或丁二烯共聚物改性的硬质PVC。除了韧性和撕裂性明显改善外，有些产品在热稳定性和硬度

9、方面亦有改进。少量聚二烯烃的存在就足以降低PVC的熔融粘度，从而改善其加工行为。甚至用液体聚丁二烯、用降解的天然橡胶和用聚氯丙烯作接枝骨架都能得到具有高抗冲性能的PVC氯乙烯在聚烯烃及其衍生物上的接枝共聚物 不少文献和专利报道过烯烃聚合物及其共聚物的氯乙烯接枝共聚物。同时认为：烯烃聚合物与PVC的相容性有限，但其TG低，耐化学腐蚀，因此适合于PVC改性，特别是在提高韧性方面。由于这类接枝共聚物具有某些独特的性能。 氯乙烯和聚乙烯的接枝共聚物是硬质或半硬质的产品，具有很高的韧性及良好的拉伸强度。较低的加工温度和良好的流动性、较高的热稳定性、良好的耐化学药品和溶剂性能。其接枝度可根据氯乙烯与聚乙烯

10、在组成的比例以及接枝反应条件来确定。 专利中报道过一种接枝共聚物，聚(乙烯-g-氯乙烯)含11(重量)的聚乙烯，在韧性、拉伸强度、伸长率、杨氏模量上比同样组成的机械共混物要好很多通过改进加工工艺，采取分批添加单体的方法可生产出适用于塑料、薄膜、板材和具有高韧性与户外耐候性良好的涂料等一系列产品。活性自由基聚合活性自由基聚合的发展 自从1956年美国科学家 Szwarc 提出活性反应( 无终止、无转移、引发速率远大于增长速率)这一有划时代意义的话题以后，人们就对活性聚合展开了研究，20世纪80年代，主要是通过形成非均相体系的物理方法来控制自由基聚合，这些体系中自由基被“包埋”而稳定，抑制了终止反

11、应，但是真正接近活性自由基的成功实例却很少。 从20世纪90年代开始，高分子化学家们着重研究通过化学方法对自由基聚合的控制，取得了巨大的进展。实现自由基活性聚合的主要方法有以下三种：1 稳定自由基方式控制的聚合反应 (stable free radical polymerization, SFRP)2 原子转移自由基聚合反应 (Atom Transfer Radical Polymerization, ATRP)3 可逆加成-裂解-链转移聚合反应 (Reversible Addition and Fragmentation Chain Transfer，RAFT)“只可意会，不可言传”？ 哇塞

12、！高分子发展真快！研究兴趣：高分子的复合与功能化； 高分子设计与合成。电话O)邮件：dingys; dingys; QQ : 864836081办公室：升华楼521；实验室：理化楼 312，217室丁运生 课题组努力工作快乐生活 Polyolefins including polyethylene (PE), polypropylene (PP), poly(1-butene), poly(1-octene), poly(4-methyl-1-pentene), ethylenepropylene elastomer (EPR) and ethylenepropyl

13、enediene rubber (EPDM) are the most important commercial polymers. Due to their excellent combination of good chemical and physical properties with low cost, superior processibility and good recyclability, polyolefins find widespread applications in modern human life. However, the major drawback of

14、polyolefins is the lack of functional groups, which poses serious problems when polyolefins are used in areas where adhesion, dyeability, printability or compatibility with other polymers is paramount. As the current development of polyolefins is being centred on the enhancement of their overall per

15、formances in order to expand their application areas, the lack of chemical functionality has become the major stumbling block. In fact, ever since the commercialization of PE and PP in the 1950s, the functionalization of polyolefins has been a very interesting research subject attracting attention f

16、rom both academic and industrial communities.The so-called polyolefin functionalization is explained as introducing polar functional groups into polyolefins. With the precondition of maintaining the desired properties of polyolefins, polyolefin functionalization confers reactivity to polyolefins, im

17、proving adhesion and compatibility between polyolefins and other materials, such as pigments, paints, glass fibers, metals, carbon black and most polymers. The application of polyolefins after functionalization can be extended to such areas that even involve catalyst supporting, medication, photoele

18、ctron material, biomaterial, photo material and environmental protection, which have never been previously accessed by polyolefinsDesign and synthesis of side group-functionalized polyolefins Theoretically, the direct, random copolymerization of -olefins with functional monomers is the most straight

19、forwardway to access side group-functionalized polyolefins.This approach has the advantages of ensuring a random distribution of the incorporated functional groups along the polyolefin chain and that the functional groups being quantitatively controllable simply by tuning the insertion efficiency of

20、 the functional monomers during copolymerization Unfortunately, due to a strong complexation between the Lewis acid components (Ti, Zr, Hf, V and Al) of the transitionmetal catalysts and the non-bonded electron pairs on N, O and X (halides) of the functional monomers, which is in preference to that

21、between the catalysts and the -electrons of the double bonds, the direct -olefin/functional monomer copolymerization usually suffers from catalyst deactivation. The development of metallocene and other single-site olefin polymerization catalysts including the less oxophilic late transition metal cat

22、alysts based on Fe, Ni, Co and Pd, has provided new opportunities for the direct copolymerization of -olefins with functional monomers. Recently, successful copolymerizations of -olefins with various functional monomers were maneuvered by either exerting steric and electronic protection on the funct

23、ional groups , or enhancing the steric hindrance of the catalyst active sites, or employing the heteroatom-resistant late transition metal catalysts . In addition, in order to avoid catalyst deactivation caused by the direct copolymerization with functional monomers, an alternative approach (the rea

24、ctive polyolefin intermediate approach) was developedGraft copolymerization approach The graft copolymerization approach is widely used to synthesize functional polyolefin graft copolymers. Its general procedure is as follows. First, grafting sites are generated in polyolefins. The grafting site can

25、 be an initiator (or its precursor) moiety for living anionic or controlled/“living” radical polymerizations (including atom transfer radical polymerization (ATRP), nitroxide-mediated stable radical polymerization (NMP) and peroxyborane-initiated stable radical polymerization) or a chain transfer ag

26、ent moiety for reversible addition-fragmentation chain transfer polymerization (RAFT). Secondly, graft polymerization of functional monomer either from (in the case of the grafting site being an initiator moiety) or onto (in the case of the grafting site being a chain transfer agent moiety) the graf

27、ting sites to obtain functional polyolefin graft copolymers. Combined the reactive polyolefin intermediate containing benzyl or vinylbenzene groups with butyllithium via a lithiation reaction to transform the pendant benzyl or vinylbenzene group to an initiator moiety of benzyllithium. The benzyllit

28、hium moieties in polyolefins initiated living anionic polymerization of styrene, methyl methacrylate (MMA) and acrylonitrile (AN) to obtain polyolefins grafted by PS, poly(methyl methacrylate) (PMMA) and polyacrylonitrile (PAN), respectively Controlled/“living” radical polymerizations are even more

29、frequently used to synthesize functional polyolefin graft copolymers due to their excellent adaptability for many polar monomers. Chung et al. ever prepared polyolefins containing alkyl-9-BBN side groups by copolymerization of -olefins with B-5-hexenyl-9-BBN over Ziegler-Natta and metallocene cataly

30、sts . In the presence of O2, the pendant alkyl-9-BBN groups in polyolefins were selectively oxidized at the aliphatic CB groups, forming peroxyborane (B-O-O-C) that initiated living radical polymerizations of various polar monomers including methacrylate and vinyl acetate . Recently, the same chemis

31、try was extended to synthesize functional graft copolymers possessing s-PSbackbone . The relatively new methods of controlled/“living” radical polymerization, including ATRP, NMP and RAFT, were also used to synthesize functional polyolefin graft copolymers. In 1998, Stehling reported copolymerizatio

32、nof -olefins (propylene or 4-methyl-1-pentene) with an alkoxyamine-substituted-olefin by a cationic metallocene catalyst rac-Et(H4Ind)2ZrMe+B(C6F5)4. This copolymerization incorporates functional alkoxyamine, a unimolecularinitiator of NMP, into polyolefins, allowing the synthesis of polyolefin-g-PS

33、 graft copolymers via NMP . Subsequently, Mulhaupt and co-workers employed Pd-based late transition metal catalysts to copolymerize ethylene and alkoxyamine-substituted -olefins. They synthesized graft copolymers of highly branched PE grafted by PS and styreneacrylonitrile random copolymers, respect

34、ively. TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy)-mediated stable radical polymerization was employed by Shimada and co-workers to prepare PP-g-PS graft copolymers from PP containing peroxide species generated by irradiation . The obtained PP-g-PS graft copolymers possess PS grafts with well-contr

35、olled molecular weight and narrow molecular weight distribution Liu and Sen carried out selective bromination of an ethylenestyrene random copolymer prepared with a metallocene catalyst, introducing bromine at the benzylidene position of the styrene unit . The ethylenestyrene random copolymer contai

36、ning benzyl bromine groups functions as a multifunctional initiator of ATRP and initiates, in the presence of CuBr and PMDETA, homopolymerizations ofMMA and styrene and block copolymerization of MMA/styrene and MMA/methacrylate (MA), respectively. Polyethylene graft copolymers with various functiona

37、l polymer grafts were synthesized . Analogously, s-PS-backboned graft copolymers were also obtained .n-溴代丁二酰亚胺 Graft copolymers from ethylene oxide and styrenePSg-PEO, graft copolymers with PEO side chains It used a macromer technique to obtain graft copolymers with uniform side chains. They synthes

38、ized a graft copolymer of PS with uniform PEO side chains through copolymerization of styrene with PEO macromer They obtained PEO macromers using potassium tertiary butoxide as initiator and methacryloyl chloride or p-vinyl benzyl chloride as terminating agent. An apparent decrease in the reactivite

39、s of both poly (ethylene oxide) macromers and comonomers was ascribed to thermodynamic repulsion between the macromer and the backbone. An amphiphilic polystyreneg-v-stearyl-polyoxyethy-lene copolymer was prepared using the macromer technique .The graft copolymers were describedas microphase separat

40、ed and can be used in applications that require blood compatibilities and antithrombogenic properties Through copolymerization of styrene with PEO macromer, prepared by anionic polymerization of EO in dimethylsulfoxide using potassium naphthalene in tetrahydrofuran as initiator, followed by terminat

41、ion with methacryloyl chloride. The reactions are shown Novel graft copolymers with styrenebutadienestyrene triblock copolymer as backbone and PEO as grafts onto the polybutadiene blocks were synthesizedSynthesis of a Novel Kind of Amphiphilic Graft Copolymer with Miktoarm Star-Shaped SideChainsIntr

42、oduction In recent years, much attention is paid to the synthesis of copolymers with different compositions and chain architectures, such as linear, grafted, comb-shaped, star-shaped, hyperbranched, and dendrimeric chains with the purpose to establish architecture-property relationships in bulk and

43、in solution. Of these various architectures, the graft copolymers, especially the amphiphilic graft copolymers, are attractive materials because of their unique chemical and physical properties as well as their potential applications in drugs, bimomaterials, nanotechnology, polymer-hybrid nanocompos

44、ites, and supermolecular science.Xiaolan Luo, Guowei Wang, Xinchang Pang, and Junlian Huang*The Key Laboratory of Molecular Engineering of Polymer, State Education Ministry of China, Department of Macromolecular Science, Fudan UniVersity,Shanghai 200433, China ReceiVed January 17, 2008ReVised Manusc

45、ript ReceiVed February 21, 2008 It is well-known that controlled polymerizations such as anionic, ATRP, and RAFT are powerful tools for the synthesis of linear polymers with well-controlled molecular weight and polydispersity,and it is possible to make topological tailoring on polymer by the reactio

46、ns of anion with some functional compounds or modification of the end groups. And “click” reactions, as termed by Sharpless are widely used in polymer chemistry during the past few years due to their high specificity, quantitative yields, and near-perfect fidelity in the presence of most functional

47、groups. Therefore, it is promising to combine the click reaction with controlled polymerization methods to synthesize the graft copolymers with complex structure.Synthesis of the Amphiphilc Graft Copolymer with Miktoarm Star-Shaped Side Chain by Click Reaction A novel kind of graft copolymers compos

48、ed of the copolymers of EO and EEGE as main chains and starshaped functionalized ABC copolymers of PS-PEO-PEEGE as side chains were described. The copolymers main chains with pending functional groups were modified to azide groups first by a series of reactions, and then the coupling reaction of the

49、 azide groups on main chain with alkyne group at PEEGE chain end of miktoarm star copolymers could be easily carried out. In summary, an amphiphilic graft copolymer with welldefined star-shaped side chains was synthesized by the “grafting onto” method via combination of anionic polymerization and cl

50、ick reactions. The azide group functionality of the main chain and the alkyne group functionality at PEEGE chain end of the miktoarm star side chains were very high. The moderate graft efficiency in click coupling reaction was obtained due to the large steric hindrance of the miktoarm star side chai

51、n. This work provided a new way to prepare the graft copolymer with complex structure.Synthesis of 2,3-epoxypropyl-1-ethoxyethyl etherPreparation of the pure cyclized product as macroinitiatorSynthesis of amphiphilic graft copolymers c-PEO-g-PCLSynthesis and Characterization of Biopolymer-Based Elec

52、trical Conducting Graft Copolymers In this study, PANI was grafted onto GG to synthesize water-soluble electrical active biomaterial for the in vivo and in vitro sensor applications. In the series of studies, the reaction mechanism, crystalline and morphological features, electrical and thermal prop

53、erties of the grafted product were extensively investigated. It has been expected that results would be leading to new promising conducting polymers especially for the sensor applications. The major advantage of this work is to use natural recourses and increase their utility in broader prospective

54、bychemical modification.Ashutosh Tiwari, S. P. SinghDepartment of Engineering Materials, National Physical Laboratory, New Delhi 110012, IndiaReceived 4 March 2007; accepted 13 October 2007DOI 10.1002/app.27789Published online 23 January 2008 in Wiley InterScience (). GG is an edible carbohydrate po

55、lymer isolated from the seeds of Cyanaposis tetragonolobus. It is a nonionic, branched-chain polymer, consisting of a straight chain of mannose units joined by linkages having -D-galactopyranose units attached to this linear chain by a linkages with molecular ratio of 1 : 2. GG is cold-water swellin

56、g biopolymer, and is reported to be one of the most highly efficient water thickeners and tablet binder Amphiphilic block copolymers consisting of hydrophilic and hydrophobic parts have been subjects of numerous studies, within which block copolymers containing hydrophilic polyoxyethylene segments a

57、nd other hydrophobic segments have attracted much attention, because polyoxyethylene segments are not only hydrophilic, but also nonionic and crystalline, and can complex monovalent metallic cations. The amphiphilic nature of these copolymers containing incompatible segments gives rise to special pr

58、operties in selective solvents, at surfaces as well as in the bulk, owing to microphase separation morphologies. They have many uses including polymeric surfactants, electrostatic charge reducers, compatibilizers in polymer blending, phase transfer catalysts or solid polymer electrolytesBlock copoly

59、mersBlock copolymers from ethylene oxide and styrenePSPEO diblock copolymers Ueda and Nagal synthesized block copolymers of styrene and EO through polycondensation between azobiscyanopentanoyl chloride and polyethylene glycol (PEG), followed by thermal decompositionin the presence of styrene Yuruk a

60、nd Ozdemir prepared the block copolymer using polymeric azocarbamate as an initiator, which was obtained by capping polyethylene glycol with aliphatic diisocyanate and subsequently by reacting this intermediate with azobiscyanopentanol. The macroazocarbamate was then used to initiate the free radica