Unimolecular ligand-initiator dual functional systems (ULIS) for low copper ATRP of vinyl monomers including acrylic/methacrylic acids

A novel approach for ATRP has been developed which enables the polymerization of vinyl monomers including those bearing carboxylic acid groups such as acrylic/methacrylic acid in the free acid form with ppm amounts of copper. The quantity of copper used in the polymerization is comparable to those left in purified polymers obtained by a conventional ATRP process.     

异丁基乙烯基醚与受电子单体的可控自由基共聚合

近年来发展起来的“活性” 可控自由基聚合越来越为人们所关注 ,其原因在于采用这种方法不仅可以设计聚合物的分子量 ,得到窄分布聚合物 ,而且聚合条件不象活性离子型聚合那样严格 ,单体适用范围相对较广 .关于烯类单体的活性自由基聚合迄今主要有 :氮氧自由基调控的稳定自由基聚合 (Ｓｔａｂｌｅｆｒｅｅｒａｄｉｃａｌｐｏｌｙｍｅｒｉｚａｔｉｏｎ ,简称ＳＦＲＰ) [1] 、原子转移自由基聚合 (Ａｔｏｍｔｒａｎｓｆｅｒｒａｄｉｃａｌｐｏｌｙｍｅｒｉｚａｔｉｏｎ ,简称ＡＴＲＰ) [2 ] 以及以后发展起来的自由基可逆加成 断链链转移聚合…     

N,N-二乙基硫代氨基甲酰硫基团(S_2CNEt_2)为假卤原子转移的原子转移自由基聚合新体系

综述了原子转移自由基聚合 (ATRP)中 ,以N ,N 二乙基硫代氨基甲酰硫基团 (S2 CNEt2 )转移实现活性聚合、控制聚合物结构的 4种新方法 :非卤化物 ,N ,N 二乙基二硫代氨基甲酸亚铜 [Cu(S2 CNEt2 ) ]催化甲基丙烯酸甲酯 (MMA)的正向ATRP ;2 ,2′ 联吡啶存在的条件下 ,过氧化苯甲酰 (BPO)与Cu(S2 CNEt2 )的氧化还原反应控制MMA的本体反向ATRP;同时含可转移卤原子、基团的氯化二乙基二硫代氨基甲酸铜 [Cu(S2 CNEt2 ) Cl]成功地用于偶氮二异丁腈或BPO引发的乙烯类单体反向ATRP.假卤原子S2 CNEt2 转移的ATRP得到窄分布的精确结构聚合物分子链ω 端含有光敏基团S2 CNEt2 ,可引发乙烯类单体的常温光聚合 ,实现ATRP与光聚合相结合制备嵌段共聚物     

Polymer Composites Based on Reactive Carboxylate-Alumoxanes

Summary: The possibility of applying basic aluminum carboxylates as the cross-linking monomers in radical polymerization processes as well as the initiators for ATRP of styrene and coordination ROP of heterocyclic monomers was examined. It was established, that aluminum carboxylates containing in their structure the acrylic and lauric acids derivatives show high activity in the copolymerization with vinyl monomers which results in the hybrid polymer networks formation. In the typical ATRP conditions, polymers grafted with styrene are obtained while basic aluminum 2-bromopropionate is used as the initiator. Hybrid composites i.e. core-shell nanospheres can be obtained in this way at low degree of polymerization. Nanoparticles of basic aluminum caroboxylates when reacted with triethylaluminum show high activity as initiators in the polymerization processes of ε-caprolactone, trimethylene carbonate as well as propylene and ethylene oxides. Cross-linked products in the form of a gel were formed as the result of ROP in such systems. However, linear polymers characterized by M_n above 10⁴ and PDI ≥ 1.9 were obtained after aluminum residuals removal.     

原子转移自由基聚合反应及其进展

活性自由基聚合是目前高分子科学中最为活跃的研究领域之一,原子转移自由基聚合反应是实现活性聚合的一种颇为有效的途径,可实现众多单体的活性可控自由基聚合。此文综述有关原子转移自由基聚合反应及其最新进展。     

Synthesis of poly(tert‐butyl acrylate‐block‐vinyl acetate) copolymers by combining ATRP and RAFT polymerizations

The synthesis of poly(tert‐butyl acrylate‐block‐vinyl acetate) copolymers using a combination of two living radical polymerization techniques, atom transfer radical polymerization (ATRP) and reversible addition‐fragmentation chain transfer (RAFT) polymerization, is reported. The use of two methods is due to the disparity in reactivity of the two monomers, viz. vinyl acetate is difficult to polymerize via ATRP, and a suitable RAFT agent that can control the polymerization of vinyl acetate is typically unable to control the polymerization of tert‐butyl acrylate. Thus, ATRP was performed to make poly(tert‐butyl acrylate) containing a bromine end group. This end group was subsequently substituted with a xanthate moiety. Various spectroscopic methods were used to confirm the substitution. The poly(tert‐butyl acrylate) macro‐RAFT agent was then used to produce (tert‐butyl acrylate‐block‐vinyl acetate). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7200–7206, 2008     

分子量规整聚p-乙烯基苯甲酸及苯乙烯p-乙烯基苯甲酸两嵌段共聚物的合成

当两嵌段共聚物为由性质不同的规制 (Ｗｅｌｌ ｄｅｆｉｎｅｄ)分子量两链段所构成时 ,在只对其中一链段为良溶剂的选择性溶剂中 ,它能够自组装形成尺寸均一的胶束 .胶束的形态与共聚物的组成、浓度、溶剂的性质等关系密切[1] .因此 ,两嵌段共聚物的合成颇被关注[2 ] .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、催化剂以及传感器等方面展示着潜在的应用前景 .规制分子量的两嵌段共聚合物的合成主要通过阴离子、阳离子、开环易位、基团转移等活性或可控聚合来实现 .但是这些方法受到单体…     

Synthesis of Rod-Coil Block Copolymers using Two Controlled Polymerization Techniques

A double-headed initiator was synthesized yielding two functional groups for the initiation of the nickel mediated ring-opening polymerization of γ-benzyl-L -glutamate-N-carboxyanhydride and controlled radical polymerization of vinyl monomers via ATRP or NMP. Well-defined block copolymers combining polypeptides and synthetic polymers were obtained.     

Block copolymerization of 5,6-benzo-2-methylene-1,3-dioxepane with conventional vinyl monomers by ATRP method

Polystyrene-block-poly(5,6-benzo-2-methylene-1,3-dioxepane) (PSt-b-PBMDO), poly(methyl methacrylate)-block-PBMDO (PMMA-b-PBMDO) and poly(methyl acrylate)-block-PBMDO (PMA-b-PBMDO) were synthesized by two-step atom transfer radical polymerization (ATRP) of conventional vinyl monomers, then BMDO. First, the polymerization of St, or MMA, or MA was realized by ATRP with ethyl α-bromobutyrate (EBrB) as initiator in conjunction with CuBr and 2,2^′-bipyridine (bpy). After isolation, polymers with terminal bromine, PSt-Br, PMMA-Br and PMA-Br, were obtained. Second, the ATRP of BMDO was performed by using macroinitiator, PSt-Br (or PMMA-Br, PMA-Br) in the presence of CuBr/bpy. The structures of block copolymers were characterized by 1H NMR spectra. Molecular weight and polydispersity index were determined on gel permeation chromatograph. Among the block copolymers obtained, PMA-b-PBMDO shows the most narrow molecular weight distribution.     

Preparation and Characterization of Homo‐ and Co‐Polymers of Some Vinyl Monomers via ATRP by Using Imine Macrocycle as Ligand

Imine macrocyclic ligand M₁ was involved in homo‐ and co‐polymerization of some vinyl monomers via atom transfer radical polymerization technique (ATRP). Hereby, vinyl acetate, styrene and methyl acrylate monomers were homopolymerized. On the other hand, they were involved in copolymerization with MMA. M₁∶CuBr∶initiator∶monomer percentages were 1∶2∶4∶400. ¹HNMR confirmed the structures of the resulting polymers. The thermal behaviors of some selected polymers were studied.     

Regenerable‐Catalyst‐Aided,Opened to Air and Sunlight‐Driven “CuAAC&ATRP” Concurrent Reaction for Sequence‐Controlled Copolymer

An ideal stimuli‐responsive controlled/living radical polymerization should have the ability to manipulate the reaction through spatiotemporal “on/off” controls, achieving the polymerization under fully open conditions and allowing for precise control over macromolecular architecture with defined molecular weights and monomer sequence. In this contribution, the photo (sunlight)‐induced electron transfer atom transfer radical‐polymerization (PET‐ATRP) can be realized to be reversibly activated and deactivated under fully open conditions utilizing one‐component copper(II) thioxanthone carboxylate as multifunctional photocatalyst and oxygen scavenger. The polymerization behaviors are investigated, presenting controlled features with first‐order kinetics and linear relationships between molecular weights and monomer conversions. More importantly, “CuAAC&ATRP” concurrent reaction combining PET‐ATRP, photodriven deoxygenation, and photoactivated CuAAC click reaction is successfully employed to synthesize the sequence‐defined multiblock functional copolymers, in which the iterative monomer additions can be easily manipulated under fully open conditions.     

Imine-based covalent organic framework as photocatalyst for visible-light-induced atom transfer radical polymerization

Photoinduced atom transfer radical polymerization (ATRP) is an economical and environment-friendly method for synthesizing polymers with pre-designable structures and precise molecular weight. Although significant progress for copper-mediated photoinduced ATRP has been achieved, several drawbacks still remain, such as poor electron transfer capability and absorption bands of photocatalysts near UV region. Herein, imine-based covalent organic framework, TAPPy-TPA-COF , has been synthesized as potential heterogeneous photocatalyst for photoinduced ATRP. The “living” feature of polymerizations of methyl methacrylate (MMA) can be well controlled by efficiency maintain the balance between activation and inactivation of Cu^I and Cu^II. The chain extension experiments have further demonstrated the chain-end fidelity of polymers. Meanwhile, the catalyst recycle experiments have revealed stability of TAPPy-TPA-COF toward ATRP processes. These results support the feasibility of using COFs as heterogeneous photocatalysts for copper-mediated ATRP under visible light irradiation.     

原子转移自由基法合成八臂星型聚苯乙烯

设计合成了星型聚合物引发剂四(2,2-二氯乙酸)季戊四醇酯(TDCAP), 并通过原子转移自由基聚合合成了八臂星型聚苯乙烯. 用FTIR, 1H NMR和GPC等手段对引发剂和星型高分子的结构进行了表征.     

Subtle ligand effects in oxidative photocatalysis with iridium complexes: application to photopolymerization

Iridium(III) complexes were designed and evaluated as efficient photoinitiators of polymerization reactions in combination with iodonium salts and silanes. Mechanistically, these reactions were shown to proceed through oxidative photoredox catalysis, generating aryl and silyl radicals under very soft irradiation conditions (blue LED, xenon lamp, and even sunlight). These radicals can initiate the free radical polymerization of acrylates or can be oxidized during the catalytic cycle to promote the ring-opening polymerization of epoxy monomers. Remarkably, both the (photo)chemical reactivity and the practical efficiency are dramatically affected by the ligands. In addition, the central role played by the oxidation ability of the excited state of the photocatalyst is discussed.     

Mechanistic and Synthetic Aspects of Atom Transfer Radical Polymerization

Abstract

Mechanistic and synthetic aspects of atom transfer radical polymerization (ATRP) are reviewed. This controlled/“living” system polymerizes many monomers including styrenes, (meth)acrylates, acrylonitrile and dienes. The halogen end groups can be converted to other functional groups such as amines and azides. In addition to producing well-defined linear homopolymers, statistical copolymers, block copolymers, and gradient copolymers, ATRP can be used to synthesize graft and hyperbranched copolymers through copolymerization with functionalized monomers. Selection of appropriate conditions for ATRP depends on targeted molecular weight and degree of polymer chain end-functionality and includes considering the monomer(s) to be polymerized, initiator structure/reactivity, amount of catalyst/deactivator used, halogen end-group used, and temperature.     

Atom transfer radical polymerization of ionic liquid monomer: The influence of salt/counterion on polymerization

Understanding the influence of salt/counterion on atom transfer radical polymerization (ATRP) is important to optimize the conditions for ATRP of ionic monomers, such as ionic liquid monomer. This article reports the results of a systematical investigation of the variables associated with ATRP in the presence of different types and amounts of salts, solvents, ligands, and monomers. A series of control ATRP experiments were conducted under various polymerization conditions. The kinetics of the polymerizations, the molecular weight, and molecular weight distribution of the formed polymers were studied by nuclear magnetic resonance and gel permeation chromatography. The results indicated that all of the studied variables influenced the ATRP process to different degrees. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2175–2184     

Hydrobromination of residual vinyl groups on divinylbenzene polymer particles followed by atom transfer radical surface graft polymerization

Rigid and monodisperse spherical polymer particles with 2.36 ± 0.18 μm diameter containing residual surface vinyl groups were prepared by photoinitiated precipitation polymerization of divinylbenzene. Anti‐Markovnikov addition of HBr to the surface vinyl groups yielded a 2‐bromoethyl functionality that was used as macroinitiator for atom transfer radical polymerization (ATRP), providing the possibility for further functionalization by controlled “grafting from” processes. This was demonstrated by grafting of glycidyl methacrylate brushes from the particle surface, using an ATRP system based on CuBr and pentamethyl diethylenetriamine. Existence of a methacrylic overlayer was verified by FTIR and XPS measurements, and the grafted particles were easily dispersed in water, confirming conversion of the particle surface from hydrophobic to hydrophilic. Hydrobromination of residual vinyl groups yields a macroinitiator that can be used for grafting of glycidyl methacrylate by ATRP. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1259–1265, 2009     

Stereoselective Polymerization of Aromatic Vinyl Polar Monomers

Polar vinyl polymers, a class of polymers with polar groups as side chains, have significant advantages over conventional nonpolar polyolefin materials in terms of viscosity, toughness, interfacial properties (dyeability and printability), and compatibility with solvents or other polymers. Among them, aromatic polar vinyl polymers are of interest because of their good heat resistance properties. In addition, stereoselective polymerization of aromatic polar vinyl monomers has been rapidly developed because the steric structure of the polymer has a significant impact on its physical properties. In this paper, we review the research progress of stereoselective polymerization catalysts for aromatic polar vinyl monomers in recent years, discuss in detail the influence of ligand structure, electronic effect of substituents, spatial site resistance effect, central rare earth metal species and polymerization solvents on the activity and stereoselectivity of polymerization reactions, and explore the possible mechanism of polymerization reaction.     

Synthesis of Block Copolymers by Combination of Atom Transfer Radical Polymerization and Visible Light‐Induced Free Radical Promoted Cationic Polymerization

A new synthetic approach for the preparation of block copolymers by mechanistic transformation from atom transfer radical polymerization (ATRP) to visible light‐induced free radical promoted cationic polymerization is described. A series of halide end‐functionalized polystyrenes with different molecular weights synthesized by ATRP were utilized as macro‐coinitiators in dimanganese decacarbonyl [Mn₂(CO)₁₀] mediated free radical promoted cationic photopolymerization of cyclohexene oxide or isobutyl vinyl ether. Precursor polymers and corresponding block copolymers were characterized by spectral, chromatographic, and thermal analyses.     

FTIR-ATR Monitoring and SEC/RI/MALLS Characterization of ATRP Synthesized Hyperbranched Polyacrylates

This work reports the synthesis at 1 L scale of hyperbranched polyacrylates based upon acrylate/diacrylate monomers such as n-butyl acrylate (nBA)/1,6-hexanediol diacrylate (HDDA) and using atom transfer radical polymerization (ATRP). A FTIR-ATR immersion probe was used to monitor the polymerization reaction. The dynamics of the build-up of polymer structure was studied by off-line analysis of samples at different reaction times by size exclusion chromatography (SEC) with detection of refractive index (RI) and multi-angle laser light scattering (MALLS) signals, leading to molecular weight distribution and z-average radius of gyration. Kinetic measurements and observed parameters of the molecular architecture are compared with theoretical predictions which can be used to design new synthesis strategies to improve the homogeneity of hyperbranched polymers. Another goal of this study was elucidating the impact on polymerization of secondary reactions such as intramolecular cyclizations. For comparison purposes, FRP (conventional radical polymerization) of the same monomers is also considered.