机理转移法合成聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)两亲性嵌段共聚物

将活性负离子聚合与原子转移自由基聚合(ATRP)技术相结合,运用机理转移法制备了一种两亲性材料聚丁二烯-b-聚(甲基丙烯酸N,N-二甲氨基乙酯)(PB-b-PDMAEMA)嵌段共聚物.首先通过负离子聚合方法设计合成聚丁二烯,用环氧丙烷封端,2-溴异丁酰溴作酯化剂,合成具有活性端基溴的聚丁二烯大分子引发剂(PB-B r),再用其引发亲水性单体DMAEMA进行原子转移自由基聚合,聚合动力学证实了该聚合反应具有典型的活性/可控自由基聚合的特征.通过差示扫描量热法(DSC)研究嵌段共聚物的微相分离行为.制备的大分子引发剂及两亲性嵌段共聚物经凝胶色谱、红外和核磁表征证实了预定的结构.     

聚甲基丙烯酸甲酯-聚甲基丙烯酸两亲性嵌段共聚物的制备及自组装形态的研究

以2-溴异丁酸乙酯为引发剂, 氯化亚铜/联二吡啶为催化剂, 通过原子转移自由基聚合(ATRP)获得分子链末端含一个α-溴原子的聚甲基丙烯酸甲酯(PMMA-Br), 以此为大分子引发剂引发甲基丙烯酸铅[Pb(MA)₂]单体进行ATRP反应, 制得P[MMA-b-Pb(MA)_2]嵌段共聚物, 将此共聚物在盐酸中进行离子交换即得聚甲基丙烯酸甲酯-聚甲基丙烯酸的两亲性嵌段共聚物[P(MMA-b-MAA)]. 用FTIR, GPC, NMR和SEM方法对共聚物进行了表征.     

苯乙烯-p-乙烯基苯甲酸两亲性嵌段共聚物在乙醇中自组装行为的电镜观察

两亲性嵌段共聚物在只对其中一链段为良溶剂的选择性溶剂中 ,能够自组装形成胶束 .胶束的形态和尺寸大小依赖于两链段的性质 ,共聚物的组成、浓度、溶剂的性质等[1] .这一性质使得嵌段共聚物在分子识别、药物和其他物质的输送、基因疗法、水系涂料、污染物的除去、纳米复合材料的制备、催化剂以及传感器等方面展示着潜在的应用前景 .因此 ,两亲性嵌段共聚物的合成及其在选择性溶剂中的自组装行为的研究近年来颇受关注[2 ] .依据两链段的比例不同 ,嵌段共聚物可形成星状胶束和“板寸头”(Ｃｒｅｗ ｃｕｔ)型胶束[3 ] .当可溶段远比不溶段长时…     

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 ,…     

由可控聚合反应直接制备不同形貌的聚集体

由可控聚合,包括活性阴离子和自由基聚合直接制备不同形貌纳米材料,是近几年来合成化学领域的一个重要研究成果.与两亲性嵌段共聚物在选择性溶剂中自组装方法不同,在选择性溶剂中进行的分散聚合,首先生成两亲性嵌段共聚物,并逐渐增加第二段聚合物的链长,以实现相分离,形成球形胶束;聚合物链继续增长,实现形貌转变,从而制备预期的聚合物形貌,包括球形胶束、纳米棒、纳米线、囊泡和复合囊泡等.本文综述了乳液聚合法制备球形胶束等形貌;描述了不同聚合体系形成的形貌以及它们的性质和应用,讨论了形貌的形成机理和控制方法,同时指出了存在的问题.     

基于聚异戊二烯嵌段共聚物的研究进展

含异戊二烯结构单元的嵌段共聚物,以其优异的性能,在自组装材料和纳米尺寸材料等领域得到了日益广泛的关注和研究。本文从合成的角度出发,系统地综述了聚异戊二烯嵌段共聚物的制备方法,特别介绍了基于聚异戊二烯嵌段合成的阴离子聚合以及活性自由基聚合中的氮氧自由基聚合(NMRP)、可逆加成-断裂链转移自由基聚合(RAFT)、原子转移自由基聚合(ATRP)等聚合方法。以可控聚合为基础的多种聚合技术综合运用是制备聚异戊二烯嵌段共聚物未来的发展方向。     

RAFT种子乳液聚合反应初期的Monte Carlo模拟

自由基聚合是制备聚合物材料最为重要的技术 .但由于自由基极易进行双基终止 ,一般很难对其结构进行精确的控制 ,所得产物分子量宽 ,组成分布不易控制 ,很难制备嵌段共聚物 . 2 0世纪 90年代出现的活性自由基聚合技术 (RAFT)克服了上述缺点 ,成为高分子化学研究的热点[1] .RAFT聚合以其适用单体广、聚合条件温和以及活性高而成为最具前途的活性自由基聚合技术之一 .迄今为止 ,RAFT的研究大多集中在溶液和本体等均相聚合体系 [2～ 5] .乳液聚合有聚合速率快、环境友好、体系粘度低等优点 ,是活性自由基聚合工业化首选工艺 ,因而近年来活…     

两亲性共聚物的分子设计与合成及其共混膜性能

从分子结构设计出发,采用自由基聚合、醚化、酯化、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)等方法合成了一系列具有不同分子结构(包括接枝、嵌段、交替、超支化等)和链形态(包括直链、梳状、哑铃状、链球状等)的两亲性共聚物,并对这些聚合物进行了谱学表征和性能测试.将这些两亲性共聚物与聚合物膜材料(包括聚偏氟乙烯、聚氯乙烯、聚砜、聚醚砜、聚醚砜酮等)进行溶液共混,通过相转化法制备共混膜,在成膜热力学和动力学分析的基础上,对共混膜的结构和性能进行调控.研究发现,两亲性共聚物在成膜过程中自发地向膜表面迁移富集,并进行自组装,在膜表面形成两亲性共聚物包膜,显著改善了聚合物多孔膜的亲水性和抗污染性能.此外,两亲性共聚物中的功能基团还可赋予共混膜某些功能特性,如生物相容性、环境响应性(pH、温度敏感性)、酶活性等.     

水分散体系中甲基丙烯酸甲酯和丙烯酸八氟戊酯嵌段共聚物的合成与表征

在聚合物链上引入氟元素可以赋予聚合物很多优异的性能 ,如良好的热稳定性、化学稳定性、生物相容性和憎水憎油性等 .含氟单体与一般单体共聚是合成含氟共聚物的重要途径 .通过原子转移自由基聚合 (ATRP)不仅可以实现多种单体的控制 (共 )聚合 ,而且可以合成出具有预定分子量、窄分子量分布以及结构明晰聚合物[1] ,我们曾报道了溶液体系中用ATRP方法合成含氟嵌段共聚物[2～ 4] .众所周知 ,大多数含氟聚合物都是通过乳液或悬浮聚合反应合成的 .然而 ,普通的乳液或悬浮聚合难以合成结构和组成可控的聚合物 ,如嵌段共聚物 ,所以近年来 ,水…     

含功能化PEO嵌段的可生物降解两亲性嵌段共聚物的可控聚合及生物医用前景（摘要）

本文采用可控聚合方法合成了一系列组成可控的由含端氨基的聚环氧乙烷（PEO）亲水链段和可生物降解的聚（ε-己内酯）（PCL）疏水链段组成的两亲性嵌段共聚物PCL-b-PEO-NH2.通过共聚物端氨基的反应活性,进一步合成了含有功能性基团的PCL-b-PEO-COOH和PCL-b-PEO-RGD两嵌段共聚物及含有温敏性组分的PCL-b-PEO-b-PNIPAAm三嵌段共聚物（PNIPAAm为聚异丙基丙烯酰胺）.     

Living Polymers in Ionic and Radical Polymerizations: Recent Developments

The discovery of living polymers, that is, assemblies of polymer molecules formed by anionic polymerization which may grow without chain-breaking reaction and may react subsequently with other monomers and various reagents through their end-groups, has led to great progress in the knowledge of the mechanism of anionic polymerization and to the synthesis of a large variety of well-defined block copolymers, graft co-polymers, and polymers with functionalized end-groups. Since only a limited number of the current monomers are polymerizable by an anionic mechanism, many attempts have been made to obtain similar results by polymerizing other monomers by cationic, radical, and Ziegler polymerization. Systems making it possible to work at temperatures higher than those used for many anionic and most cationic polymerizations would be particularly interesting.     

Synthesis and Characterization of Star-branched Polyisobutylene by Combination of Anionic Polymerization and Cationic Polymerization

The construction of polymer materials with controlled compositions, topologies, and functionalities has been the enduring focus in current research1,2. Among them, star polymers have been extensively studied for a long time, due to their markedly lower so…     

Polymerization of 1,3,5-Tri(1,3,5,7-tetra)-methyl-1,3,5-tri(1,3,5,7-tetra)-10-carbomethoxydecylctri(tetra)siloxane

The cationic and anionic polymerization of 1,3,5-tri(1,3,5,7-tetra)methyl-1,3,5-tri (1,3,5,7-tetra)-10-carbomethoxydecylcyclotri (tetra) siloxane, catalyzed by sulfuric acid and alkali metal naphthalenes, respectively, was studied. With sulfuric acid the polymer yield increased with increasing catalyst concentration, while the molecular weights decreased. With potassium naphthalene the polymerization reaction was first order to monomer, and the molecular weights increased linearly with increasing the percent conversion in accordance with a “living” polymerization. In both cases the polymerization was an equilibrium reaction and the conversion was about 85%. Only low molecular weight polymers were obtained due to steric effects of the bulky long-chain substituents.     

Synthesis of a novel centipede-like copolymer of styrene and methyl methacrylate

A well-defined,A2B-type,centipede-like copolymer of styrene and methyl methacrylate(PS-PS-PMMA) was synthesized by the combination of living anionic polymerization and atom transfer radical polym-erization(ATRP) . The synthetic approach involves the coupling reaction of polystyrene(PS) backbone bearing 1,1-diphenylethene(DPE) pendant groups,produced by ATRP and Wittig reaction,with living polystyryllithium(PSLi) ,and subsequent polymerization of the resulting 1,1-diphenylmethyl anions with methy methacrylate. The centipede-like copolymer was characterized by 1H NMR,IR,SEC,SLS,and DSC measurements.     

Direct through anionic,cationic, and radical active species: Terminal carbon–halogen bond for “controlled”/living polymerizations of styrene

In this work, we examined the synthesis of novel block (co)polymers by mechanistic transformation through anionic, cationic, and radical living polymerizations using terminal carbon–halogen bond as the dormant species. First, the direct halogenation of growing species in the living anionic polymerization of styrene was examined with CCl₄ to form a carbon–halogen terminal, which can be employed as the dormant species for either living cationic or radical polymerization. The mechanistic transformation was then performed from living anionic polymerization into living cationic or radical polymerization using the obtained polymers as the macroinitiator with the SnCl₄/n‐Bu₄NCl or RuCp^*Cl(PPh₃)/Et₃N initiating system, respectively. Finally, the combination of all the polymerizations allowed the synthesis block copolymers including unprecedented gradient block copolymers composed of styrene and p‐methylstyrene. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019 , 57, 465–473     

活性正离子聚合方法合成两亲性共聚物研究进展

综述由活性正离子聚合方法设计合成两亲性共聚物与两亲性聚合物网络的研究进展 ,并进一步介绍这些两亲性聚合物在生物材料领域的应用。     

Seed polymerization of tetraethyl orthosilicate in the presence of anionic and cationic polystyrene colloidal spheres

Kinetic analyses are made for the seed polymerization of tetraethyl orthosilicate (TEOS) in the presence of anionic and cationic polystyrene colloidal sphere seeds by turbidity and dynamic light-scattering measurements. Transmission-electron microscopy pictures of the spheres formed are also used. The seed polymerization of TEOS is difficult to take place on the surface of anionic polystyrene spheres (44–212 nm in diameter). On the other hand, the reaction proceeds easily on the cationic polystyrene spheres. Hairy and soft surfaces of polystyrene spheres will disturb the seed polymerization. Furthermore, the electrostatic attraction between the anionic hydrolytic products of TEOS molecules and cationic polystyrene spheres plays an important role for the seed polymerization.     

Synthesis and characterization of a novel well-defined comb-like ionomer

A novel well-defined comb-like ionomer with cations was synthesized by the combination of living anionic polymerization and atom transfer radical polymerization (ATRP). The synthetic approach involves the coupling reaction of polystyrene (PS) backbone bearing 1,1-diphenylethene (DPE) pendant groups with living polystyryllithium (PSLi), subsequent amine functionalization of the resulting 1,1-diphenylmethyl anions with 3-dimethylaminopropyl chloride (DMAPC), and quaternization of tertiary amino groups with hydrochloric acid. The comb-like ionomer was characterized by ¹H NMR, IR, GPC measurements and end-group titrition.     

Comparison of living polymerization systems

Recent developments in the field of living polymerization are surveyed. Comparison of the available mechanistic and kinetic information is made for living anionic, cationic, free radical, group transfer, ring-opening metathesis, Ziegler-Natta and immortal polymerizations. This evaluation indicates that the majority of living polymerizations involve quasiliving equilibrium between active (propagating) and dormant (nonpropagating) polymer chains. On the basis of the kinetics of a general model for quasiliving and ideal living polymerizations it is concluded that ideal living polymerization is a special subclass of quasiliving polymerizations. Classification of living polymerization systems is also attempted.     

Relation between the reactivities of vinyl monomers in ionic polymerizations and their 1H NMR spectra

¹H NMR chemical shifts of the protons in the vinyl groups of monomers are correlated with their reactivities in anionic, coordinated anionic, and cationic polymerizations. The relative reactivities of styrenes in anionic addition reactions with living polystyrene increase linearly with the chemical shift of the proton trans to the substituent (δ_H1). Only the plot for 2,4,6-trimethylstyrene deviates very much from the linear relation because of the large steric hindrance. The relative reactivities of methacrylates in anionic copolymerizations increase with increasing chemical shifts of protons attached to the β-carbon of methacrylates. In cationic polymerizations of styrenes, the relative reactivities decrease with increasing δ_H1. The relative reactivities in coordinated anionic polymerizations with Ti-containing Ziegler initiators show a typical feature of cationic polymerization, and those with V-containing initiators show a typical feature of anionic polymerization, indicating the importance of the coordination process in the propagation reaction with Ti-containing initiator systems. From the results, it can be concluded that the chemical shifts of the protons attached to the β-carbon of vinyl monomers can be used as a practical measure of the reactivity of vinyl monomers in ionic polymerizations and also as a tool for understanding the mechanism of polymerization. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2134–2147, 2002