环形侧链聚合物刷的合成与表征

通过grafting-onto方法合成高侧链接枝密度的环形侧链聚合物刷并进行结构表征.先通过开环易位聚合(ROMP)制备带有炔基侧基的线形聚降冰片烯衍生物主链(l-PND),通过原子转移自由基聚合(ATRP)和铜催化的叠氮-炔环加成(Cu AAC)反应制备带有一个叠氮基的环形聚丙烯酸叔丁酯侧链(c-Pt BA),再利用Cu AAC反应将环形侧链高密度地接入主链,得到环形侧链聚合物刷.通过核磁氢谱(1H-NMR)、凝胶渗透色谱(GPC)和红外光谱(IR)对聚合物主/侧链及聚合物刷的结构和组成进行了表征.该聚合物刷主链聚合度为400,高接枝密度的环形侧链使主链构象伸展.聚合物刷在原子力显微镜(AFM)下呈单分子蠕虫形貌(柱状形貌),分子长度为200 nm,直径为30 nm.     

原子转移自由基聚合在分子结构设计中的应用进展

原子转移自由基聚合(ATRP)是一种新型"活性"/可控聚合技术,可有效地实现对聚合物分子结构的设计,精准地控制聚合物分子结构。本文在介绍了官能团反应法、偶联反应法以及自由基聚合法制备ATRP大分子引发剂的基础上,进一步介绍了通过控制大分子引发剂"活性"点位置进行聚合物结构设计。同时还着重综述了大分子引发剂在嵌段聚合物、梳状聚合物、分子刷聚合物、树状及超支化聚合物和星形聚合物分子设计中的应用。     

ATRP大分子引发剂的合成及应用

原子转移自由基聚合(ATRP)是一种新型的可控/活性聚合技术,现已广泛应用于聚合物分子结构设计、无机材料表面修饰、蛋白质检测以及生物大分子的分离和杀菌防污等.在此类反应过程中涉及的三大要素:单体、引发体系(引发剂、催化剂、配位剂)及反应介质,其中核心要素为ATRP引发剂,其结构与性质是ATRP反应成败的决定因素之一.本文在综述了小分子引发剂的种类与性质及ATRP的反应机理的基础上,着重综述了近年来官能团反应法、偶联反应法及自由基聚合法制备ATRP大分子引发剂的最新进展.同时还综述了大分子引发剂通过ATRP反应在聚合物结构设计中的应用,以及对无机材料和生物材料的表面修饰的最新进展,最后对ATRP引发体系的未来发展与应用进行了展望.     

ATRP与点击化学结合制备树状星型聚合物

本文通过将ATRP技术和点击化学相结合的方法来制备树状星型聚合物[(PMMA)2PSt]4. 首先通过1,3-偶极环加成反应对ATRP的核预聚物进行端基修饰, 得到后继ATRP反应的大分子引发剂, 进而引发第二单体的ATRP聚合生成树状星型聚合物.     

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     

酶催化原子转移自由基聚合

原子转移自由基聚合(ATRP)是制备分子量以及分散度可控聚合物的重要途径。然而,受制于除氧步骤复杂、金属催化剂残留以及单体适用范围有限等因素,ATRP难以应用于批量制备功能化聚合物/共聚物材料,限制了其进一步应用。近年来提出和发展的酶催化聚合,为高效便捷除氧、拓展单体适用范围以及制备具有特殊(纳米)结构的纯净聚合物/共聚物提供了新思路。本文详细介绍了酶的结构与催化机理,以酶的种类进行分类,系统总结了具有不同结构的酶催化体系(包括过氧化辣根酶、血红蛋白、血红素、漆酶等)的催化机理、适用单体、优缺点及应用等;综述了酶以及酶模拟物催化ATRP体系的发展现状;最后,对酶催化ATRP的发展前景和挑战进行了探讨和展望。     

原子转移自由基聚合在锂电池用聚合物电解质设计中的应用

聚合物电解质(PE)由于具有无液体渗漏、界面相容性好、热和化学稳定，制备工艺简单等优点，成为下一代高能量密度锂电池用电解质的最佳候选。然而，没有任何一种聚合物能同时满足锂电池用PE对于力学性能和电化学性能的要求，因此人们通过共混、交联等手段来对PE基体的成分和结构进行改性，以期提升PE的综合性能。通过传统的自由基聚合方法得到的PE基体的成分和结构不易控制，阻碍了PE的理论和改进研究。原子转移自由基聚合(ATRP)技术通过活性种和休眠种之间的可逆平衡使自由基维持在较低浓度，可以实现PE上接枝的支链分子量的调控和精细结构的设计，为制备力学性能和电化学性能相协调的PE提供了有效途径。而且，由于ATRP引发基团的可设计性，在PE无机填料的改性和界面性能的优化上均具有突出的优势，对于聚合物基纳米复合聚合物电解质膜的锂电池综合性能提升具有重要意义。本文综述了ATRP技术在PE的基体制备、填料改性及界面优化中的应用，并对其未来发展方向做出了展望。     

可控自由基聚合系列实验教学中的一些尝试与经验*

设计了基于可控自由基聚合的系列实验教学,包括:单体和引发剂精制、RAFT试剂合成、不同单体的RAFT/ATRP聚合、RAFT聚合制备嵌段聚合物、ATRP制备嵌段聚合物等。这些实验环环相扣,互相支撑,又有着明显的对比效果。这种尝试有效改进和扩充了常规高分子合成教学中的自由基聚合部分,有效激发了学生的主动性,提高了其分析问题、解决问题的能力。     

原子转移自由基聚合(ATRP)在星形聚合物合成中的应用

综述了近10 年来采用原子转移自由基聚合(ATRP) 法合成星形聚合物的研究进展。从聚合单体、引发剂、聚合方法和反应条件以及聚合物性质等方面讨论了原子转移自由基聚合在星形聚合物合成中的应用,并根据聚合方法和引发剂对各种反应进行了分类。对原子转移自由基聚合技术在合成功能性复杂星形聚合物中的应用进行了展望。     

3-氯-2-氯甲基-1-丙烯引发苯乙烯原子转移自由基聚合的研究

原子转移自由基聚合(ATRP)是一种活性自由基聚合方法,通过它可以合成结构可控的官能性聚合物[1].双官能性聚合物是制备嵌段聚合物[2]和模型网络的前驱体[3,4],具有较大的理论和应用价值,寻求新的双官能引发剂以获得末端官能性聚合物已经成为当前ATRP研究领域的重要研究方向之一     

Synthesis of mikto‐topology star polymer containing one cyclic arm

Well‐defined mikto‐topology star polystyrene composed of one cyclic arm and four linear arms was synthesized by a combination of atom transfer radical polymerization (ATRP) and Cu‐catalyzed azide‐alkyne cycloaddition (CuAAC) click reaction. First, the bromine‐alkyne α,ω‐linear polystyrenes containing four hydroxyl groups protected with acetone‐based ketal groups were synthesized by ATRP of styrene using a designed initiator. Then, the bromine end‐group was converted to the azide and the linear polystyrene was cyclized intra‐molecularly by the CuAAC reaction. The four hydroxyl groups were released by deprotection and then esterified with 2‐bromoisobutyryl bromide to produce a cyclic polymer bearing four ATRP initiating units. By subsequent ATRP of styrene to grow linear polymers with the cyclic polystyrene as a macroinitiator, the mikto‐topology star polymers were prepared. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Well‐controlled ATRP of 2‐(2‐(2‐azidoethyoxy)ethoxy)ethyl methacrylate for high‐density click functionalization of polymers and metallic substrates

The combination of atom transfer radical polymerization (ATRP) and click chemistry has created unprecedented opportunities for controlled syntheses of functional polymers. ATRP of azido‐bearing methacrylate monomers (e.g., 2‐(2‐(2‐azidoethyoxy)ethoxy)ethyl methacrylate, AzTEGMA), however, proceeded with poor control at commonly adopted temperature of 50 °C, resulting in significant side reactions. By lowering reaction temperature and monomer concentrations, well‐defined pAzTEGMA with significantly reduced polydispersity were prepared within a reasonable timeframe. Upon subsequent functionalization of the side chains of pAzTEGMA via Cu(I)‐catalyzed azide‐alkyne cycloaddition (CuAAC) click chemistry, functional polymers with number‐average molecular weights (M_n) up to 22 kDa with narrow polydispersity (PDI < 1.30) were obtained. Applying the optimized polymerization condition, we also grafted pAzTEGMA brushes from Ti6Al4 substrates by surface‐initiated ATRP (SI‐ATRP), and effectively functionalized the azide‐terminated side chains with hydrophobic and hydrophilic alkynes by CuAAC. The well‐controlled ATRP of azido‐bearing methacrylates and subsequent facile high‐density functionalization of the side chains of the polymethacrylates via CuAAC offers a useful tool for engineering functional polymers or surfaces for diverse applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1268–1277     

Quantification of ATRP initiator density on polymer latex particles by fluorescence labeling technique using copper‐catalyzed azide‐alkyne cycloaddition

We developed a novel fluorescence labeling technique for quantification of surface densities of atom transfer radical polymerization (ATRP) initiators on polymer particles. The cationic P(St‐CPEM‐C₄DMAEMA) and anionic P(St‐CPEM) polymer latex particles carrying ATRP‐initiating chlorine groups were prepared by emulsifier‐free emulsion polymerization of styrene (St), 2‐(2‐chloropropionyloxy)ethyl methacrylate (CPEM), and N‐n‐butyl‐N,N‐dimethyl‐N‐(2‐methacryloyloxy)ethylammonium bromide (C₄DMAEMA). ATRP initiators on the surface of polymer particles were converted into azide groups by sodium azide, followed by fluorescent labeling with 5‐(N,N‐dimethylamino)‐N′‐(prop‐2‐yn‐1‐yl)naphthalene‐1‐sulfonamide (Dansyl‐alkyne) by copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). The reaction time required for both azidation of ATRP‐initiating groups and successive fluorescence labeling of azide groups with Dansyl‐alkyne by CuAAC were investigated in detail by FTIR and fluorescence spectral measurement, respectively. The ATRP initiator densities on the cationic P(St‐CPEM‐C₄DMAEMA) and anionic P(St‐CPEM) particle surfaces were estimated to be 0.21 and 0.15 molecules nm^?2, respectively, which gave close agreement with values previously determined by a conductometric titration method. The fluorescence labeling through click chemistry proposed herein is a versatile technique to quantify the surface ATRP initiator density both on anionic and cationic polymer particles. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4042–4051     

Simultaneous Photoinduced ATRP and CuAAC Reactions for the Synthesis of Block Copolymers

Atom transfer radical polymerization (ATRP) and copper‐catalyzed azide–alkyne cycloaddition (CuAAC) reactions, both utilizing copper(I) (Cu(I)) complexes, make a tremendous progress in synthetic polymer chemistry. Independently or in combination with other polymerization processes, they give access to the synthesis of polymers with well‐defined structures, desired molecular architectures, and a wide variety of functionalities. Here, a novel in situ photoinduced formation of block copolymers is described by simultaneous ATRP and CuAAC processes. This approach relies on the direct reduction of initially charged copper(II) complexes to Cu(I) complexes to trigger both ATRP and CuAAC reactions coinciding under UV light at ambient temperature in one pot. Its synthetic utility is demonstrated on a model block copolymerization process by photoinduced ATRP of methyl methacrylate (MMA) using an initiator possessing acetylene functionality and concomitant click reaction between thus formed α‐acetylene‐poly(methyl methacrylate) (Ac‐PMMA) and independently prepared azide functional polystyrene (PS‐N₃). Successful formation of PS‐b‐PMMA block copolymer is confirmed by FT‐IR and ¹H NMR spectral analysis and gel permeation chromatography (GPC) measurements.

     

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.     

Triphilic pentablock copolymers with perfluoroalkyl segment in central position

Adding perfluoroalkyl (PF) segments to amphiphilic copolymers yields triphilic copolymers with new application profiles. Usually, PF segments are attached as terminal blocks via Cu(I) catalyzed azide-alkyne cycloaddition (CuAAC). The purpose of the current study is to design new triphilic architectures with a PF segment in central position. The PF segment bearing bifunctional atom transfer radical polymerization (ATRP) initiator is employed for the fabrication of triphilic poly(propylene oxide)-b-poly(glycerol monomethacrylate)-b-PF-b-poly(glycerol monomethacrylate)-b-poly(propylene oxide) PPO-b-PGMA-b-PF-b-PGMA-b-PPO pentablock copolymers by a combined ATRP and CuAAC reaction approach. Differential scanning calorimetry indicates the PF-initiator to undergo a solid–solid phase transition at 63°C before the final crystal melting at 95°C. This is further corroborated by polarized optical microscopy and X-ray diffraction studies. The PF-initiator could successfully polymerize solketal methacrylate (SMA) under typical ATRP conditions producing well-defined Br-PSMA-b-PF-b-PSMA-Br triblock copolymers that are then converted into PPO-b-PSMA-b-PF-b-PSMA-b-PPO pentablock copolymer via CuAAC reaction. Subsequently, acid hydrolysis of the PSMA blocks afforded water soluble well-defined triphilic pentablock copolymers PPO-b-PGMA-b-PF-b-PGMA-b-PPO with fluorophilic central segment, hydrophilic middle blocks, and lipophilic outer blocks. The triphilic block copolymers could self-assemble, depending upon the preparatory protocol, into spherical and filament-like phase-separated nanostructures as revealed by transmission electron microscopy.     

An ultrasensitive fluorescent aptasensor based on truncated aptamer and AGET ATRP for the detection of bisphenol A

Given the gigantic harmfulness of bisphenol A (BPA), a novel and ultrasensitive aptasensor, which employs the truncated BPA aptamer, click chemistry, and activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP), was developed herein for the quantitative determination of BPA. Firstly, hairpin DNAs (hairpins) with a thiol at the 5′ end and an azide group at the 3′ end were conjugated with aminated magnetic beads (MBs) through heterobifunctional cross-linkers. BPA truncated aptamer (ssDNA-A) hybridizes with its complementary single-stranded DNA (ssDNA-B) to form double-stranded DNA. In the presence of BPA, ssDNA-A specifically captures BPA, and then ssDNA-B is released. Subsequently, the ssDNA-B hybridizes with hairpins to expose the azide group near the surface of the MBs. Then, propargyl-2-bromoisobutyrate (PBIB), the initiator of AGET ATRP containing alkynyl group, was conjugated with azide group of hairpins via the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Consequently, a large number of fluorescein-o-acrylate (FA) were introduced to the MBs through AGET ATRP, resulting in that the fluorescence intensity was increased dramatically. Obviously, the fluorescence intensity was especially sensitive to the change of BPA concentration, and this method can be used in quantitative determination of BPA. Under optimal conditions, a broad liner range from 100 fM to 100 nM and a low limit of detection (LOD) of 6.6 fM were obtained. Moreover, the method exhibits not only excellent specificity for BPA detection over BPA analogues but high anti-interference ability in real water sample detection, indicating that it has huge application prospect in food safety and environment monitoring.

     

Click approaches in sol–gel chemistry

The combination of the copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction with sol–gel processing enables the versatile preparation of sol–gel materials under different shapes with targeted functionalities through a diversity-oriented approach. In this account, the development of the CuAAC reaction under anhydrous conditions for the synthesis of sol–gel precursors and for the assembling of magnetic nanoparticles on self-assembled monolayers is related, as well as the use of the classical CuAAC methodologies for the functionalization of mesoporous silica nanoparticles and microdots arrays. Coupling CuAAC and Sol–Gel will result in simplified preparations of multifunctional materials with controlled morphologies.     

Recent advances of CuAAC click reaction in building cyclic polymer

Cyclic polymers have attracted more and more attentions in recent years because of their unique topological structures and characteristic properties in both solution and bulk state. There are relatively few reports on cyclic polymers, partly because of the more demanding synthetic procedures. In recent years, “click” reaction, especially Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC), has been widely utilized in the synthesis of cyclic polymer materials because of its high efficiency and low susceptibility to side reactions. In this review, we will focus on three aspects: (1) Constructions of monocyclic polymer using CuAAC “click” chemistry; (2) Formation of complex cyclic polymer topologies through CuAAC reactions; (3) Using CuAAC “click” reaction in the precise synthesis of molecularly defined macrocycles. We believe that the CuAAC click reaction is playing an important role in the design and synthesis of functional cyclic polymers.     

Application of click chemistry to the production of DNA microarrays

The copper-catalyzed alkyne-azide cycloaddition (CuAAC) reaction was applied as the novel method of DNA immobilization on a modified solid support. The CuAAC click reaction enables the covalent binding of DNA modified with pentynyl groups at its 5'-end to azide-loaded slides. Click microarrays were produced using this approach and successfully employed in biological/model experiments.