基于双锂法的炔基功能化热塑性弹性体的合成

苯乙烯-异戊二烯-苯乙烯三嵌段聚合物(SIS)是目前广泛使用的一种热塑性弹性体(TPE)材料, 建立高效、 精准、 普适的SIS功能化方法一直是提高TPE材料性能的关键. 首先, 利用双烯单体与单官能度引发剂的反应合成了双官能度的双锂引发剂; 然后采用双锂引发法, 以炔基功能化单体封端, 高效合成了α,ω-端炔基官能化SIS聚合物. 采用叔丁醇锂作为异戊二烯聚合段的调节剂, 叔丁醇钾作为苯乙烯聚合段的调节剂, 合成了低乙烯基结构含量(5.8%)、 窄分子量分布(<1.17)的SIS三嵌段聚合物; 再向SIS三嵌段聚合物中一步加入炔基官能化的1,1-二苯基乙烯(DPE)衍生物进行封端, 以高于90%的收率高效合成了α,ω-端炔基官能化SIS三嵌段模块聚合物, 借助炔基的高效点击反应, 实现了功能化及拓扑化TPE材料的制备.     

Fast surface immobilization of native proteins through catalyst-free amino-yne click bioconjugation

Surface immobilization provides a useful platform for biosensing, drug screening, tissue engineering and other chemical and biological applications. However, some of the used reactions are inefficient and/or complicated, limiting their applications in immobilization. Herein, we use a spontaneous and catalyst-free amino-yne click bioconjugation to generate activated ethynyl group functionalized surfaces for fast immobilization of native proteins and cells. Biomolecules, such as bovine serum albumin (BSA), human IgG and a peptide of C(RGDfK), could be covalently immobilized on the surfaces in as short as 30 min. Notably, the bioactivity of the anchored biomolecules remains intact, which is verified by efficiently capturing target antibodies and cells from the bulk solutions. This strategy represents an alternative for highly efficient surface biofunctionalization.

Fast surface immobilization of native bioconjugates through a spontaneous amino-yne click reaction is realized.     

A fluorescent supramolecular crosslinked polymer gel formed by crown ether based host-guest interactions and aggregation induced emission

Based on the combination of B21C7/dialkylammonium salt host-guest interactions and tetraphenylethylene(TPE)-based aggregation-induced emission(AIE) effect, a fluorescent supramolecular crosslinked polymer gel was successfully prepared. Compared with the solution of TPE-containing small molecules, this gel exhibited remarkable fluorescence enhancement due to the AIE effect of TPE units. The "gelation induced fluorescence emission" phenomenon can be explained by the hindered intramolecular rotation of phenyl rings of TPE. Because of the reversibility and stimuli-responsiveness of the B21C7/dialkylammonium salt host-guest interactions, the transition between the fluorescent supramolecular crosslinked polymer gel and the disassembled sol with very weak fluorescence can be realized by adding p H and thermal stimuli. This novel material contributes to the development of supramolecular chemistry, polymer science and fluorescent materials and offers a new method to construct functional supramolecular materials.     

In Situ Synthesis of AIEgen-based Porous Organic Polymer Films by Interfacial Amino-yne Click Polymerization for Efficient Light-Harvesting

We developed a catalyst-free, atom-economical interfacial amino-yne click polymerization to in situ synthesize new aggregation-induced emission luminogen (AIEgen)-based free-standing porous organic polymer films at room temperature. The crystalline properties of POP films were confirmed by powder X-ray diffraction and high-resolution transmission electron microscopy. The good porosity of these POP films was proved by their N₂ uptake experiments. The thickness of POP films can be easily regulated from 16 nm to ≈1 μm by adjusting monomer concentration. More importantly, these AIEgen-based POP films show bright luminescence with high absolute photoluminescent quantum yields up to 37.8 % and good chemical and thermal stability. The AIEgen-based POP film can encapsulate an organic dye (e.g., Nile red) to further form an artificial light-harvesting system with a large red-shift (Δλ=141 nm), highly efficient energy-transfer ability (Φ_ET=91 %), and high antenna effect (11.3).     

Hydrogel-Based Macroscopic Click Chemistry

The click reaction has found good utility across various fields due to the characteristics of high efficiency, atom economy, simple and mild reaction conditions. Click chemistry is usually utilized for connecting components of microscopic level, while it is still unable for joining macroscopic building blocks. Materials consisting of macroscopic building blocks realize the flexible fabrication of three-dimensional structures at macroscopic level, exerting significance on parallel manufactures. In this work, we reported macroscopic click chemistry utilizing hydrogel as macroscopic building blocks. Hydrogels G1 and G2 were prepared by incorporating M1 (N,N′-dimethyl-1,2-ethanediamine) and P1 (alkyne functionalized polyethylene glycol) respectively, where polymer chains formed through diffusion-induced amino-yne click reaction entangled different hydrogel networks together. Additionally, chain-like aggregates and complicated 3D structures such as tetrahedron and quadrangular pyramid were constructed based on the adhesion of the hydrogel blocks. The approach enables us to find more possibilities in the delicate designation of 3D aggregations as well as large-scale manufacturing.     

Organic Nanoprobes for Fluorescence and 19F Magnetic Resonance Dual‐Modality Imaging

Multimodal imaging techniques have been demonstrated to be greatly advantageous in achieving accurate diagnosis and gained increasing attention in recent decades. Herein, we present a new strategy to integrate the complementary modalities of ¹⁹F magnetic resonance imaging (¹⁹F MRI) and fluorescence imaging (FI) into a polymer nanoprobe composed of hydrophobic fluorescent organic core and hydrophilic fluorinated polymer shell. The alkyne‐terminated fluorinated copolymer (Pn) of 2,2,2‐trifluoroethyl acrylate (TFEA) and poly(ethylene glycol) methyl ether acrylate (PEGA) was first prepared via atom transfer radical polymerization (ATRP). The PEGA plays an important role in both improving ¹⁹F signal and modulating the hydrophilicity of Pn. The alkynyl tail in Pn is readily conjugated with azide modified tetra‐phenylethylene (TPE) through click chemistry to form azo polymer (TPE‐azo‐Pn). The core‐shell nanoprobes (TPE‐P3N) with an average particle size of 57.2 ± 8.8 nm are obtained via self‐assembly with ultrasonication in aqueous solution. These nanoprobes demonstrate high water stability, good biocompatibility, strong fluorescence and good ¹⁹F MRI performance, which present great potentials for simultaneous fluorescence imaging and ¹⁹F–MR imaging.     

“点击”反应在制备环状聚合物中的应用

环状聚合物具有不同于线性高分子的独特性质,是一类具有应用前景的新型聚合物材料,但复杂的结构导致其合成过程复杂繁琐.＂点击＂化学由于其高效、可靠、高选择性的特点已成为拓扑高分子合成的新方法,活性自由基聚合（ATRP、RAFT和NMP）具有聚合物结构可控等特点,二者联用为环状聚合物的合成拓宽了思路.本文就近几年＂点击＂反应、＂点击＂反应与活性自由基聚合联用以及其他方法联用在环状聚合物中的应用进行综述.＂点击＂反应与这些方法的结合将在功能性环状聚合物的设计与合成中发挥积极的作用.     

"Clicking" on/with polymers: a rapidly expanding field for the straightforward preparation of novel macromolecular architectures

The combination of controlled polymerization techniques and "click" reactions form an efficient platform for the preparation of polymers in various architectures. In this critical review, an update of our 2007 review in Chem. Soc. Rev., we focus on the "click" reactions that have been used widely in the last four years to create new polymer architectures. Not only block copolymers and star-shaped polymers but also cyclic and dendritic macromolecules could be synthesized using these robust "click" reactions (205 references).     

Synthesis of 3-miktoarm stars and 1st generation mikto dendritic copolymers by "living" radical polymerization and "click" chemistry

The facile synthesis of 3-miktoarm star polymers and 1st generation mikto polymeric dendrimers using atom transfer radical polymerization (ATRP) and "click" chemistry is demonstrated. ATRP was used to synthesize near uniform polymers with Br chain ends, which were easily converted into azido groups. These polymer chains were then attached to a trifunctional alkyne molecule (tripropargylamine) using click reactions in a variety of ways to make the miktoarm stars and miktoarm polymeric dendrimers.     

Mechanism-Guided Design of Chain-Growth Click Polymerization Based on a Thiol-Michael Reaction

The development of chain-growth click polymerization is challenging yet desirable in modern polymer chemistry. In this work, we reported a novel chain-growth click polymerization based on the thiol-Michael reaction. This polymerization could be performed efficiently under ambient conditions and spatiotemporally regulated by ultraviolet light, allowing the synthesis of sulfur-containing polymers in excellent yields and high molecular weights. Density functional theory calculations indicated that the thiolate addition to the Michael acceptor is the rate-determining step, and introducing the phenyl group could facilitate the chain-growth process. This polymerization is a new type of chain-growth click polymerization, which will provide a unique approach to creating functional polymers.     

Visualization of Atom Transfer Radical Polymerization by Aggregation‐Induced Emission Technology

Aggregation‐induced emission (AIE) technology has been demonstrated to be a facile approach for in‐situ monitoring atom transfer radical polymerization (ATRP). A series of tertraphenyl ethylene (TPE)‐containing α‐bromo compounds were synthesized and applied as ATRP initiators. The photoluminescent (PL) emission of the polymerization system is proved to be sensitive to the local viscosity owing to the AIE characteristics of TPE. Linear relationships between the resulting molecular weight M_n and PL intensity were observed in several polymerization systems with different monomers, indicating the variability of this technique. Compared to physical blending, the chemical bonding of the TPE group in the chain end has higher sensitivity and accuracy to the polymer segments and the surrounding environment. This work promoted the combination of the AIE technique and controlled living radical polymerization, and introduced such an optical research platform to the ATRP polymerization process.     

Simple Biosensor with High Selectivity and Sensitivity: Thiol‐Specific Biomolecular Probing and Intracellular Imaging by AIE Fluorogen on a TLC Plate through a Thiol–Ene Click Mechanism

A handy, specific, sensitive bioprobe has been developed. Tetraphenylethene (TPE) was functionalized by a maleimide (MI) group, giving a TPE‐MI adduct that was nonemissive in both solution and the solid state. It was readily transformed into a fluorogen showing an aggregation‐induced emission (AIE) property by the click addition of thiol to its MI pendant. The click reaction and the AIE effect enabled TPE‐MI to function as a thiol‐specific bioprobe in the solid state. Thus, the spot of TPE‐MI on a TLC plate became emissive when it had been exposed to L ‐cysteine, an amino acid containing a thiol group, but remained nonemissive when exposed to other amino acids that lack free thiol units. The thiol‐activated emission was rapid and strong, readily detected by the naked eye at an analyte concentration as low as approximately 1 ppb, thanks to the “lighting up” nature of the bioprobing process. Similarly, the emission of TPE‐MI was turned on only by the proteins containing free thiol units, such as glutathione. Clear fluorescence images were taken when living cells were stained by using TPE‐MI as a visualization agent, affording a facile fluorescent maker for mapping the distribution of thiol species in cellular systems.     

Sponge-like nanostructured conducting polymers for electrically controlled drug release

An electrically controlled drug release (ECDR) system based on sponge-like nanostructured conducting polymer (CP) polypyrrole (PPy) film was developed. The nanostructured PPy film was composed of template-synthesized nanoporous PPy covered with a thin protective PPy layer. The proposed controlled release system can load drug molecules in the polymer backbones and inside the nanoholes respectively. Electrical stimulation can release drugs from both the polymer backbones and the nanoholes, which significantly improves the drug load and release efficiency. Furthermore, with one drug incorporated in the polymer backbone during electrochemical polymerization, the nanoholes inside the polymer can act as containers to store a different drug, and simultaneous electrically triggered release of different drugs can be realized with this system.     

Azide-alkyne click polymerization: An update

The great achievements of click chemistry have encouraged polymer scientists to use this reaction in their field.This review assembles an update of the advances of using azide-alkyne click polymerizati...     

Recyclable Cu nanoparticle catalyzed azide-alkyne click polymerization

The Cu(I)-catalyzed alkyne-azide cycloaddition(CuAAC) has been developed into a powerful polymerization reaction for the synthesis of new polytriazoles with versatile properties. However, research on recyclable and reusable copper catalyst for click polymerization to meet the requirement of green chemistry was rarely reported. Copper nanoparticles were reported to be capable catalysts for CuAAC. Replacing conventional copper catalyst with copper nanoparticles may realize the recycle and reuse of the copper catalyst in click polymerization. In this paper, copper nanoparticles were prepared and used as an effective catalyst for click polymerization, and soluble polytriazoles with high molecular weights were obtained in excellent yields under optimized reaction conditions. Importantly, the copper nanoparticles can be recycled and reused for up to 11 times for the click polymerization. Moreover, introducing aggregation-induced emission(AIE)-active moiety of tetraphenylethylene into the monomers makes the resultant polymers retain the AIE feature. This work not only provides an efficient recyclable catalytic system for the azide-alkyne click polymerization, but also might inspire polymer chemists to use recyclable copper species to catalyze other polymerizations.     

Click polymerization: The aurora of polymer synthetic methodology

As an emerged efficient polymerization methodology, the click polymerization plays a significant role in the area of polymer and materials sciences. Similar to the click reaction, the click polymerization enjoys the advantages of high efficiency, mild reaction conditions, and high regio- and stereo-selectivity etc. In this highlight, we summarize the recent progress on click polymerizations, with focus on the alkyne-based ones. The challenges and opportunities in this area are also briefly discussed. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 616–621     

Copolymers with fluorescence properties in mesoporous silica SBA-15:Synthesis and characterization

A novel copolymer with fluorescence properties in mesoporous silica SBA-15 was prepared via a combination of surface-initiated reversible addition-fragmentation chain transfer(RAFT) polymerization and "click" chemistry.A sufficient amount of peroxide groups were introduced into mesoporous silica SBA-15 channel pores and were further used to initiate the RAFT polymerization of styrene and 4-vinylbenzyl azide,resulting in SBA-15 supported polystyrene-co-poly(4-vinylbenzyl azide) copolymer(PS-co-PVBA/SBA-15) hybrid material.The samples were characterized by Fourier transform infrared spectroscopy(FT-IR),transmission electron microscopy(TEM),thermogravimetry analysis(TGA),N_2 adsorption-desorption isotherms and X-ray diffraction(XRD),respectively.The results show that the styrene and 4-vinylbenzyl azide had copolymerized inside mesoporous silica SBA-15.Subsequently,Npropargyl-carbazole(PC) was connected to PS-co-PVBA/SBA-15 hybrid material via "click" reaction,resulting in PS-co-PVBC/SBA-15 with carbazole side groups hybrid material.The fluorescence spectrum is dominated by a broad band from 350 nm to 400 nm in narrow region and the maximum peak is 362 nm,indicating the characteristic absorption of the carbazole group of PS-co-PVBC/SBA-15 hybrid material.     

Click Chemistry: A Potential Platform for Development of Novel Dental Restorative Materials

The main aim of this study is to develop novel polymer modified glass-ionomer cement (GIC) glasses utilizing click chemistry and RAFT polymerization. These novel glasses can serve as a platform to improve the properties of GIC's by incorporating chemistries and formulations that are not normally compatible with GIC's. Aluminofluoro-silicate glasses utilized in glass-ionomer dental cements were coated with azide terminated silane groups. In addition, a copolymer of acrylic acid-itaconic acid containing alkyne groups was synthesized by RAFT polymerization and was coupled via ‘click’ chemistry with the azide-coated GIC glass particles. FT-IR spectroscopy was used to characterize the synthesized materials and to confirm completion of the ‘click’ coupling reaction. The experimental cements cured, demonstrating that these modified glasses could be utilized in GIC formulations. The long setting and working times compared to control groups indicate that further improvements are necessary to fully utilize this chemistry. Our initial results in this study demonstrated the successful application of click chemistry in developing novel dental restorative materials, specifically glass-ionomer cements.     

Fast, ligand- and solvent-free copper-catalyzed click reactions in a ball mill

A new, ligand- and solvent-free method for the Huisgen 1,3-dipolar cycloaddition (click reaction) was developed using a planetary ball mill. Besides various alkynes and azides, a propargyl functionalized polymer was converted by mill clicking. Moreover, it was possible to carry out a click polymerization in a ball mill.     

Efficient Homodifunctional Bimolecular Ring‐Closure Method for Cyclic Polymers by Combining RAFT and Self‐Accelerating Click Reaction

An efficient metal‐free homodifunctional bimolecular ring‐closure method is developed for the formation of cyclic polymers by combining reversible addition‐fragmentation chain transfer (RAFT) polymerization and self‐accelerating click reaction. In this approach, α,ω‐homodifunctional linear polymers with azide terminals are prepared by RAFT polymerization and postmodification of polymer chain end groups. By virtue of sym‐dibenzo‐1,5‐cyclooctadiene‐3,7‐diyne (DBA) as small linkers, well‐defined cyclic polymers are then prepared using the self‐accelerating double strain‐promoted azide–alkyne click (DSPAAC) reaction to ring‐close the azide end‐functionalized homodifunctional linear polymer precursors. Due to the self‐accelerating property of DSPAAC ring‐closing reaction, this novel method eliminates the requirement of equimolar amounts of telechelic polymers and small linkers in traditional bimolecular ring‐closure methods. It facilitates this method to efficiently and conveniently produce varied pure cyclic polymers by employing an excess molar amount of DBA small linkers.