可控活性自由基聚合制备端基官能化聚合物研究进展

端基官能化聚合物是指那些在聚合物末端或悬垂端含有活性官能团的聚合物。它们可发挥交联剂或扩链剂的作用,从而制备出不同结构特点的嵌段聚合物、接枝聚合物、星型、超支化或树状聚合物。文章主要对引发转移终止剂(Iniferter)法、原子转移自由基聚合(ATRP)、氮氧自由基调控聚合(NMRP)和可逆加成-断裂链转移自由基聚合(RAFT)等可控活性自由基聚合方法在制备端基官能化聚合物中的应用进行了介绍。最后对可控活性自由基聚合在功能性聚合物制备中的应用前景进行了展望。     

Photocontrolled living polymerizations

Living polymerizations involve the creation of polymer chains without significant irreversible chain transfer or chain termination. Such processes are widely used to access well-defined macromolecular materials with controlled architectures, such as block and star polymers. Although this concept was first realized for anionic polymerizations in the 1950s, many key recent advances have been made, most notably in the area of radical polymerization. Here, we report a living photopolymerization that involves photoexcited monomers. Exposure of metal-containing ferrocenophane monomers to Pyrex-filtered light from a mercury lamp (lambda>310 nm) or to bright sunlight in the presence of an anionic initiator leads to living polymerizations, in which the conversion and molecular weight of the resulting polymer can be controlled by the irradiation time. Photoirradiation selectively weakens the iron-cyclopentadienyl bond in the monomer, allowing the use of moderately basic and highly functional-group-tolerant initiators. The polymerization proceeds through attack of the initiator and propagating anion on the iron atom of the photoexcited monomer and, remarkably, the polymerization rate decreases with increasing temperature. Block copolymer formation is possible when the light source is alternately switched on and off in between sequential addition of different monomers, providing unprecedented, photocontrolled access to new types of functional polymers.     

Controlled radical polymerization

Fundamentals of controlled/“living” radical polymerization are given together with a discussion of selected initiating/catalytic systems which provide structural, compositional, and functionality control during radical polymerization. Four systems which enable the synthesis of polymers with low polydispersities (M_w/M_n< 1.2), relatively high molecular weights (M_n>10 000), and high degrees of functionality are: nitroxide-mediated polymerization of styrene and styrene copolymers; organometallic compounds used for polymerization of acrylates; atom transfer radical polymerization of various monomers; and the degenerative transfer process. Also important in this field are new structural features and potential applications of controlled radical polymerization.     

Synthesis and characterization of radiopaque iodine-containing methacrylate-based polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization

The reversible addition-fragmentation chain transfer (RAFT) polymerization of 2-(2′-iodobenzoyl) ethyl methacrylate (2-IEMA) was performed in benzene solution using 4-cyanopentanoic acid dithiobenzoate (CPADB) as chain transfer agent to yield well-defined iodine-containing methacrylate-based polymers. It is characteristic of a controlled/living polymerization, i.e., linear increase in M _n with conversion and narrow molecular distribution. Moreover, the block copolymerization of 2-IEMA with 2-(2′,3′,4′,6′-tetra-O-acetyl-β-Dglucosyloxy) ethyl methacrylate (AcGEMA) and 2-lactobionamidoethyl methacylate (LAMA) was also carried out to give radiopaque glycopolymers by using the same methodology, respectively. The radiopacity of these polymers was evidenced by a routine medical X-ray imaging technique. TEM and DLS analytical results showed that the selected PIEMA-b-PLAMA diblock copolymers can self-assemble in aqueous solution into nearly spherical aggregates of 60–86 nm in diameter.     

Recent developments in anionic polymerization

The past year witnessed very significant advances in the living anionic polymerization of (meth)acrylate monomers, particularly in hydrocarbons at or below 0°C. Block polymerization of alkyl methacrylates with primary alkyl acrylates, although somewhat improved, remains a challenge. Anionic polymerization of styrene, diene and its derivatives was carried out with the aim of synthesizing functional polymers and block copolymers of various architectures. There has been a trend towards combining different living techniques in order to design polymers of unique architectures and properties     

星型聚合物合成方法与应用研究进展

介绍了星型聚合物的合成技术路线以及活性离子聚合法、原子转移自由基聚合法、开环聚合法、自组装法和联结反应法等新型合成方法。阐述了星型聚合物的应用进展。第三代至第七代的聚酰胺-胺星型聚合物在体内的毒性很低;聚乳酸星型聚合物可作为药物释放控制剂;在聚合物共混中作为添加剂,可提高其它聚合物的热稳定性、韧性和染色能力;支链数目为...     

链转移剂单体合成支化聚苯乙烯及其表征

以α-甲基丙烯酸和3-巯基己醇为原料,采用直接酯化法合成了链转移剂单体α-甲基丙烯酸-3-巯基己酯(MMH)。以偶氮二异丁腈(AIBN)为引发剂,在MMH存在下进行苯乙烯的常规自由基聚合反应。通过高效液相色谱、气相色谱、三检测凝胶渗透色谱(TD-GPC)和核磁共振氢谱(1H-NMR)对链转移剂单体、聚合反应过程和聚合物进行了表征分析。结果表明,链转移剂单体MMH的纯度可以达95%以上,以MMH为支化单体,可以通过常规自由基聚合反应合成支化聚苯乙烯,得到的支化聚苯乙烯不但具有相对较高的分子量和相对较窄的分子量分布(-Mw.MALLS=370300,-Mw/-Mn=6.9),而且具有较高的支化程度因而表现出较低的特性黏度(g′=0.427)。     

含聚氧乙烯链段的嵌段共聚物和接枝共聚物的合成及性能

综述了由聚氧乙烯链段与聚二烯烃、聚异丁烯、聚乙烯基吡啶、聚丙烯腈、聚丙烯酰胺或聚丙烯酸链段组成的各种嵌段共聚物及接枝共聚物的合成,并对其各种性能,包括两亲性质、络合碱金属离子性及微观相分离等进行了总结。     

含醛基聚合物的"活性"/可控自由基聚合研究进展

主要综述了利用原子转移自由基聚合(ATRP)和"活性"/可控RAFT自由基聚合合成结构明确的、分子量大小和分布可控的含醛基聚合物,以及所得聚合物与蛋白质、酶、药物等生物分子通过Schiff碱连接形成的生物分子-聚合物缀合物的最新研究;同时也简单介绍了由"活性"/可控自由基聚合所得的两亲性醛基聚合物纳米胶束的形成,并展望了含醛基聚合物今后可能的发展方向.     

"活性"/可控自由基聚合制备含糖聚合物的研究进展

含有糖单元的聚合物因其在药学和生物技术等领域的潜在应用价值吸引了科研工作者的广泛关注.文中介绍了原子转移自由基聚合(ATRP),氮氧稳定自由基聚合(NMP),可逆加成断裂链转移聚合(RAFT)等"活性"/可控自由基聚合在制备含糖聚合物中的应用进展,重点介绍了上述三种聚合方法对含糖聚合物分子量和结构的控制.     

Core-cross-linked polymer micelles via living polymerizations

This work reports a general synthesis to core-cross-linked polymer micelles directly from monomers by two typical living polymerizations, anionic polymerization and atom transfer radical polymerization. The micelle concentrations are hundred times higher than those by traditional synthetic method using selective solvents. The morphologies of polymer micelles can be controlled to be spheres, fibers, and graft-like aggregates by varying the experimental conditions. Micelles with the same polymer in both the core and the shell have also been synthesized by this approach.     

Block copolymer synthesis

The efficient synthesis of structurally well-defined block copolymers is exciting and important area of research. This article describes several methods for the preparation of di- and triblock copolymers. Examples are taken from the literature and include anionic, cationic, free-radical and metal-catalyzed polymerizations that are useful for the preparation of these hybrid materials. In addition, examples that combine these polymerization mechanisms are described.     

Addition of “Living” Polymers onto C60.

Abstract

Various “living” polymers were grafted onto C₆₀ The number of arms of the so obtained “star” molecules can be controlled by stoechiometry and/or by varying the reactivity of the carbanion on the “living” chain against a double bond on the C₆₀. Even the oxanion of “living” polyethylenoxide is able to add onto the reactive double bonds on C₆₀. In some conditions, the carbanions present on these alkaline salts of grafted fullerenes becomes able to initiate anionic polymerization of vinyl monomers. Using “living” poly(phenylvinylsulfoxide) as a precursor polymer for PA, polyacetylene chains could be attached to the fullerene.     

N-甲基苯基马来酰亚胺与苯乙烯嵌段共聚物的合成和研究

通过自由基聚合和负离子聚合两条途径合成了Ｎ－甲基苯基马来酰亚胺与苯乙烯的嵌段共聚物，并用自由基聚合的方法合成了二者的无规共聚物。研究并对比了它们的热失重性能和亲水－疏水性质，结果表明，嵌段共聚物具有较好的热稳定性，同时疏水性也较强。     

醋酸乙烯酯的“活性”/可控自由基聚合研究进展

醋酸乙烯酯在聚合中容易发生链转移和链终止反应,所以实现醋酸乙烯酯的"活性"/可控自由基聚合是一个巨大的挑战。文中从不同的活性自由基聚合方法角度对醋酸乙烯酯的"活性"/可控自由基聚合研究进行了综述。在众多活性自由基聚合方法中以黄原酸酯、二硫代胺基甲酸酯为链转移剂的RAFT聚合和以乙酰丙酮钴络合物为调控剂的钴调控自由基聚合真正实现了它的"活性"/可控自由基聚合。     

单分散聚甲基丙烯酸乙酯的制备与性能研究

活性阴离子聚合为聚合物分子设计和合成提供了一种有效方法.以1,1二苯基己基锂(DPHLi)为引发剂,添加LiClO4络合剂,采用活性阴离子聚合体系制备了单分散聚甲基丙烯酸乙酯(PEMA).考察了聚合温度、引发剂、添加剂等工艺参数对聚合反应的影响规律,并研究了不同pH值聚甲基丙烯酸乙酯的降解性能.     

可逆加成-断裂链转移活性自由基聚合

讨论了可逆加成-断裂链转移(RAFT)活性自由基聚合的反应机理、RAFT试剂的制备以及RAFT反应的研究进展。并对RAFT反应的应用作了简要的介绍。     

Synthesis of Microspheres as Versatile Functional Scaffolds for Materials Science Applications

Functional polymeric microspheres are of great interest as they have high potential as functional scaffolds in material science applications. Highly cross‐linked poly(divinyl benzene) (pDVB) microspheres can be synthesized via the precipitation polymerization technique. Recently, various methods of controlled polymerization techniques (e.g., atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer (RAFT), and anionic ring‐opening polymerization (AROP)) and highly orthogonal conjugation methods (e.g., copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition of azides and terminal alkynes (CuAAc), thiol‐ene addition and RAFT hetero Diels–Alder cycloaddition (RAFT‐HDA)) have been applied to functionalize microspheres via the “grafting from” and “grafting to” approaches. The synthesis of pDVB microspheres, their subsequent modification via grafting of polymer strands to the surface, and the characterization of the obtained functional particles are reviewed.     

丙烯酸系三元嵌段共聚物的合成与表征

利用基团转移聚合（ＧＴＰ）技术,在室温下使用单官能团引发剂,通过对单体加料顺序与时机的控制,合成了一系不同组成比,不同分子量的聚甲基丙烯酸甲酯－聚丙烯酸正丁酯（或乙酯）－聚丙烯腈嵌段共聚物,用ＦＴ－Ｉ,Ｈ－ＮＭＲ,ＧＰＣ等方法对共聚物进行表征,共聚过程活性中心的转移机理。     

Thermal behaviour of nylon 6-poly (ether-esteramide) block copolymers

Block copolymers have been produced by anionic polymerization of caprolactam with end-functionalized soft-block components derived from polymeric polyols. This method of synthesis gives rise to linear segmented block copolymers with alternating polyether soft blocks and polyamide hard blocks. Copolymers with 10–50% w/w of polyether polyol prepolymer have been the particular focus of attention in this work because of their better physical integrity than copolymers of other compositions. Their phase inversion and morphology/property relationships have been examined by means of differential thermal calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). In this work, the polymers have been hand-cast, but the materials do find application in the reaction injection moulding field.