Metallopolymers with transition metals in the side-chain by living and controlled polymerization techniques

Work on side-chain transition metal-containing polymers prepared by controlled and living polymerizations is summarized, including living anionic polymerization (LAP), ring-opening metathesis polymerization (ROMP) and controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). These polymers include metallocene-containing polymers, ferrocenylsilane polymers with additional metal at the side chain, metal carbonyl complex polymers, and ligated metal complex polymers.     

活性自由基聚合研究的新动态──可逆加成-断裂链转移自由基聚合

介绍了基于可逆链转移思想的“活性”／控制自由基聚合。着重介绍澳大利亚Ｒｉｚｚａｒｄｏ研究小组的最新研究成果：以双硫酯类化合物为链转移剂的可逆加成－断裂链转移自由基聚合。分析其活性特征,并阐明其反应机理     

Photomediated controlled radical polymerization

Photomediated controlled radical polymerization is a versatile method to prepare, under mild conditions, various well-defined polymers with complex architecture, such as block and graft copolymers, sequence-controlled polymers, or hybrid materials via surface-initiated polymerization. It also provides opportunity to manipulate the reaction through spatiotemporal control. This review presents a comprehensive account of the fundamentals and applications of various photomediated CRP techniques, including atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT), nitroxide mediated polymerization (NMP) and other procedures. In addition, mechanistic aspects of other photomediated methods are discussed.     

甲基丙烯酸酯/二甲基丙烯酸酯自由基共聚合体系中的自加速和凝胶行为

对甲基丙烯酸聚乙二醇单醚酯/二甲基丙烯酸聚乙二醇酯共聚体系分别实施常规自由基聚合（FRP）,原子转移自由基聚合（ATRP）和可逆加成-断裂链转移（RAFT）自由基聚合,通过观察聚合速率、双键转化率、凝胶点以及交联网络的发展,比较FRP、ATRP和RAFT共聚合体系的反应动力学和交联行为。3个聚合体系均出现了自加速现象,ATRP体系的自加速由扩散控制的自由基脱活造成,RAFT体系的自加速来自于扩散控制的自由基加成。在ATRP和RAFT交联体系中,初级链的缓慢增长和充分松弛减少了分子内环化,抑制了微凝胶形成,因此其凝胶点远低于FRP体系。ATRP和RAFT交联网络通过凝胶自由基与单体加成以及支化链的结合而不断发展,导致凝胶含量和交联网络密度随转化率不断增大。     

Comparison of reaction kinetics and gelation behaviors in atom transfer, reversible addition-fragmentation chain transfer and conventional free radical copolymerization of oligo(ethylene glycol) methyl ether methacrylate and oligo(ethylene glycol) dimethacrylate

The reaction kinetics and gelation behavior in atom transfer radical polymerization (ATRP), reversible addition-fragmentation chain transfer (RAFT), and conventional free radical copolymerizations (FRP) of oligo(ethylene glycol) methyl ether methacrylate (OEGMEMA) and oligo(ethylene glycol) dimethacrylates (OEGDMAs) were investigated and compared with respect to the polymerization rate, gel point, and the evolution of network with vinyl conversion. All the three systems experienced autoacceleration in the reaction rate but occurred at different regions of vinyl conversion, caused by diffusion-controlled radical reactions: termination in the FRP, addition in the RAFT, and deactivation in the ATRP, respectively. In the FRP, significant amount of gel materials was collected by solvent extraction far before the onset of macro-gelation detected by an abrupt increase in complex viscosity. However, in the RAFT and ATRP, no gels were found until the systems approached their macro-gelation points. The observation suggests limited intramolecular crosslinking/cyclization reactions in the ATRP and RAFT systems. This is because the slow growth of primary chains (ATRP and RAFT in hours versus FRP in seconds) allowed adequate chain relaxation and diffusion of reacting species. The gel materials thus synthesized by ATRP and RAFT are expected to be more homogeneous in network structure than that by FRP.     

基于RAFT聚合策略合成功能化聚烯烃嵌段聚合物的研究进展

首先介绍了可逆加成-断裂链转移聚合（RAFT）的聚合机理及其常用的RAFT试剂,并与其它两种活性可控自由基聚合[氮氧化合物媒介的自由基聚合（NMP）和原子转移自由基聚合（ATRP）]进行了简单的优缺点对比。其次,介绍了近些年在基于RAFT聚合制备功能化聚烯烃嵌段聚合物研究中取得的进展,重点综述了制备功能化聚烯烃嵌段聚合物时所采用的6种方法,包括①烯烃配位聚合与RAFT聚合相结合;②阴离子聚合与RAFT聚合相结合;③阳离子聚合与RAFT聚合相结合;④Click反应与RAFT聚合相结合;⑤开环聚合与RAFT聚合相结合;⑥叶立德活性聚合与RAFT聚合相结合。最后,对基于RAFT聚合策略设计合成功能化聚烯烃嵌段聚合物的研究前景与实际应用进行了展望。     

活性自由基乳液聚合的研究进展

活性自由基乳液聚合是一个非常新的研究领域。介绍了目前活性自由基乳液聚合领域的3种常用的方法及应用这些方法进行乳液聚合的研究进展,包括:原子转移自由基聚合(ATRP),氮氧调节自由基聚合(NMP)和可逆加成-断裂链转移自由基聚合(RAFT)。     

Synthesis of Glycopolymers by Controlled Radical Polymerization Techniques and Their Applications

Natural saccharides are involved in numerous biological processes. It has been shown that these carbohydrates play a role in cell adhesion and proliferation, as well as protein stabilization, organization, and recognition. Certain carbohydrates also serve as receptors for viruses and bacteria. They are over expressed in diseases such as cancer. Hence, a lot of effort has been focused on mimicking these sugars. Polymers with pendent saccharide groups, also known as glycopolymers, are studied as oligo‐ and polysaccharide mimics. Controlled radical polymerization (CRP) techniques such as atom transfer radical polymerization (ATRP), reversible addition–fragmentation chain transfer (RAFT) polymerization, and nitroxide‐mediated polymerization (NMP), as well as cyanoxyl‐mediated free radical polymerization have allowed chemists to synthesize well‐defined glycopolymers that, in some cases, have particular end‐group functionalities. This review focuses on the synthesis of glycopolymers by these methods and the applications of glycopolymers as natural saccharide mimics.     

Side-Chain Metallocene-Containing Polymers by Living and Controlled Polymerizations

This review summarizes recent work on side-chain metallocene-containing polymers prepared by controlled and living polymerizations, which include living anionic polymerization (LAP), ring-opening metathesis polymerization (ROMP) and controlled radical polymerization (CRP) such as atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer polymerization (RAFT), and nitroxide-mediated polymerization (NMP). The majority of efforts in the field are focused on side-chain ferrocene-containing polymers, while cobaltocenium-containing polymers have recently started to draw attention. Future direction on the development of other metallocene-containing polymers is discussed.     

可控/活性聚合在无机粒子表面接枝研究进展

介绍了一些主要的可控／活性自由基聚合法,包括氮氧调解自由基聚合法（NMRP）、原子转移自由基聚合法（ATRP）、可逆加成断裂链转移聚合法（RAFT）在粒子表面接枝聚合形成无机纳米粒子／聚合物的壳核结构,达到了对粒子改性的目的。并提出了一些目前研究中存在的问题,对可控／活性聚合应用的发展进行了展望。     

Advances in RAFT polymerization: the synthesis of polymers with defined end-groups

This paper provides an overview and discusses some recent developments in radical polymerization with reversible addition-fragmentation chain transfer (RAFT polymerization). Guidelines for the selection of RAFT agents are presented. The utility of the RAFT process is then illustrated with several examples of the synthesis of polymers with reactive end-groups. Thus, RAFT polymerization with appropriately designed trithiocarbonate RAFT agents is successfully applied to the synthesis of narrow polydispersity carboxy-functional poly(methyl methacrylate) and primary amino-functional polystyrene. Methods for removing the thiocarbonylthio end-group by aminolysis, reduction and thermal elimination are discussed. It is shown that the thiocarbonylthio end-group can be cleanly cleaved by radical induced reduction with tri-n-butylstannane, to leave a saturated chain end, or by thermolysis, to leave an unsaturated chain end.     

基于环糊精的星形聚合物的合成方法研究进展

综述了基于环糊精（CD）的星形聚合物合成方法的研究进展,涉及开环聚合、原子转移自由基聚合（AT-RP）、点击反应以及可逆加成-断裂链转移（RAFT）聚合等.     

Probing mechanistic features of conventional, catalytic and living free radical polymerizations using soft ionization mass spectrometric techniques

The present feature article provides an overview on the use of state-of-the-art mass spectrometry techniques such as matrix assisted laser desorption and ionization time of flight (MALDI-TOF) mass spectrometry as well as electrospray ionization mass spectrometry (ESI-MS) for probing the mechanism of free radical polymerization processes. The article features representative examples of the application of mass spectrometry techniques to conventional free radical polymerization, nitroxide mediated polymerization (NMP), atom transfer radical polymerization (ATRP), reversible addition fragmentation chain transfer (RAFT) as well as catalytic chain transfer (CCT) processes.     

丙烯腈嵌段共聚物的合成及其自组装研究进展

综述了含聚丙烯腈(PAN)嵌段共聚物的合成方法及其在溶液中的自组装技术。对常用的活性自由基聚合方法,如原子转移自由基聚合(ATRP)、可逆加成断裂链转移(RAFT)聚合、氮氧自由基聚合(NMP)以及钴调介自由基聚合(CMRP)等方面的研究进行了总结,同时对PAN类嵌段共聚物在溶液中的自组装技术进行了概括。最后提出了现有技术存在的问题,并对其今后发展方向进行了展望。     

Alkylation of polyethyleneimine for homogeneous ligands in ATRP

Ethylated and butylated polyethyleneimine ligands were synthesized and employed in copper catalyzed atom transfer radical polymerization of styrene and methyl methacrylate with suitable initiators in order to obtain homogeneous polymerizations, resulting in well defined polymers with low polydispersities. Linear curves drawn from kinetics and conversion-molecular weight plots indicate that all the polymerizations were successfully controlled. In ATRP reactions of S and MMA, the apparent rate of polymerization, k_p^app, exhibits a plateau at [Ligand]/[CuBr] ≥ 0.5 ratio for both ligands. The apparent rate constant also decreases by increasing the alkyl chain length of the alkylated polyethyleneimine ligand. Ethylated and butylated polyethyleneimine ligands in ATRP of S and MMA were found to be faster than the existing ATRP ligands.     

End‐functional polymers,thiocarbonylthio group removal/transformation and reversible addition–fragmentation–chain transfer (RAFT) polymerization

This review focuses on processes for thiocarbonylthio group removal/transformation of polymers synthesized by radical polymerization with reversible addition‐fragmentation‐chain transfer (RAFT). A variety of processes have now been reported in this context. These include reactions with nucleophiles, radical‐induced reactions, thermolysis, electrocyclic reactions and ‘click’ processes. We also consider the use of RAFT‐synthesized polymers in the construction of block or graft copolymers, functional nanoparticles and biopolymer conjugates where transformation of the thiocarbonylthio group is an integral part of the process. This includes the use of RAFT‐synthesized polymers in other forms of radical polymerization such as atom transfer radical polymerization or nitroxide‐mediated polymerization, and the ‘switching’ of thiocarbonylthio groups to enable control over polymerization of a wider range of monomers in the RAFT process. With each process we provide information on the scope and, where known, indicate the mechanism, advantages and limitations. Copyright © 2011 Society of Chemical Industry     

壳聚糖接枝改性及其在生物医学领域的应用

壳聚糖作为重要的天然生物材料,其改性与应用得到了广泛关注.综述了近年来壳聚糖的化学接枝改性方法,包括开环聚合法(ROP)、原子转移自由基法(ATRP)、可逆加成断裂链转移聚合法(RAFT)、以及氮氧稳定自由基聚合法(NMP)等.并进一步综述了壳聚糖接枝共聚物在药物控释栽体、基因载体、组织工程材料等生物医学领域的应用.     

Synthesis of Miktoarm Dumbbell-Like Amphiphilic Triblock Copolymer by Combination of Consecutive RAFT Polymerizations and ATRP

Summary  A novel synthetic route, combining three reversible addition-fragmentation chain transfer (RAFT) and one atom transfer radical polymerization (ATRP) processes, for the preparation of a miktoarm dumbbell-like amphiphilic triblock copolymer, poly(poly(ethylene glycol) methyl ether methacrylate)-b-polystyrene-b-(poly(4-vinylbenzyl chloride)-g-polystyrene) (PPEGMA-b-PS-b-(PVBC-g-PS)), was developed using 2-cyanoprop-2-yl 1-dithionaphthalate (CPDN) as a RAFT agent, and the benzyl chloride group of the VBC units in the PVBC block as active ATRP macroinitiators, respectively. The structures of the obtained (co)polymers were characterized by ¹H NMR spectroscopy. The obtained PPEGMA-b-PS-b-(PVBC-g-PS) amphiphilic triblock graft copolymer could self-assemble into spherical micelles with 100-300 nm diameters in a selective solvent.     

Particle Size Limits of RAFT Living Emulsion Polymerization,with Xanthate-Based Transfer Agent

With a xanthate-based low activity RAFT (reversible addition–fragmentation chain transfer) agent, the living emulsion polymerization system follows zero-one kinetics and particles are smaller than their characteristic cross over diameter. The size and kinetic limitations in RAFT emulsion were investigated by using the concept of crossover size, based on a mechanistic approach. The main reason for these limitations is attributed to the low transfer constant, which tends to render desorption of a radical from particles difficult, the incoming z-mer has a higher probability to propagate relative to the addition process in RAFT equilibrium. In contrast, the living mini-emulsion polymerization follows either zero-one or pseudo-bulk kinetics, depending on the initial droplet size and reaction conditions.     

活性/可控自由基细乳液聚合的研究及工业化进展

综述了活性/可控自由基细乳液聚合方法的研究进展,主要包括稳定自由基细乳液聚合、原子转移自由基细乳液聚合和可逆加成-断裂链转移自由基细乳液聚合3种"活性"/可控自由基聚合方法,介绍了近年来这些领域的工业化进程,并指出了该体系的发展与不足。