聚集诱导发光材料在聚合物制备及性能检测中的应用进展

聚集诱导发光(AIE)材料因其独特的发光性能,已在荧光检测、生物成像及有机发光器件等领域展现出较为广阔的应用前景。本文综述了AIE材料在监测聚合物制备过程(本体聚合、溶液聚合、乳液聚合及悬浮聚合过程等)中的应用,介绍了利用AIE分子的荧光信号响应检测聚合物玻璃化转变温度、粘度、相分离程度、分子量等物理性能的研究,为AIE材料在聚合过程可视化监测及聚合物荧光功能化领域的应用提供了参考。最后对AIE材料在高分子科学研究中的应用前景进行了展望。     

RAFT聚合合成高分子量嵌段聚合物

以合成高分子量聚合物为目标,以苯基二硫代乙酸-1-苯基乙酯(PEPDTA)作为RAFT试剂,研究引发剂的种类(偶氮二异丁腈(AIBN)、1-1′-偶氮环己腈(ACC))、用量及聚合温度对苯乙烯/丙烯酸丁酯RAFT共聚合过程和聚合物结构的影响.结果发现,由于体系中RAFT浓度很低,相应的引发剂浓度要比传统自由基聚合低得多,只有采用较高的聚合温度和低分解速率常数的引发剂(ACC),才能制得无活性聚合物分率低(<0.1)、分子量高的聚合物,并进一步得到杂质含量少、分子量分布窄的嵌段聚合物.     

末端四苯乙烯荧光团标记法研究双亲性嵌段聚合物的自组装行为

以四苯乙烯类分子2-溴-2-甲基-丙酸-3-(4-三苯乙烯基-苯氧基)-丙醇酯(E)作为引发剂,N-异丙基丙烯酰胺和苯乙烯为原料,通过活性自由基聚合,合成了末端具有聚集诱导发光(AIE)活性发光体的双亲性嵌段聚合物G。 详细研究了AIE活性引发剂E和嵌段聚合物G在不同状态下的光物理行为差异。结果表明,在相同浓度条件下,随着温度的升高,引发剂E分散液的荧光强度不断下降。 而嵌段聚合物的荧光强度先上升,当温度超过37 ℃后,嵌段聚合物的荧光强度不断下降。 同样地,通过改变引发剂E和嵌段聚合物G在四氢呋喃和水混合溶剂中的浓度发现,随着浓度的减小,引发剂E的荧光强度不断下降,而嵌段聚合物分散液在改变分散液浓度时荧光强度的变化规律和改变温度时荧光强度的变化趋势相似。 通过监控双亲性嵌段聚合物末端挂接的AIE活性发光分子发光性质的变化可以间接表征其聚集态结构的变化。     

含氟丙烯酸酯与苯乙烯共聚物的RAFT合成及表征

通过可逆加成-断链链转移(RAFT)溶液聚合,以三硫代碳酸酯为RAFT试剂,偶氮二异丁腈(AIBN)为引发剂,1,4-二氧六环为溶剂,制备甲基丙烯酸(2,2,2-三氟)乙酯(TFEMA)和苯乙烯(St)共聚物.详细研究了不同引发剂的用量、RAFT试剂与引发剂摩尔比以及聚合温度等实验条件对聚合反应过程的影响.通过GPC、FTIR测试共聚物的分子量、分子量分布和分子结构,并用静态接触角仪和AFM分别表征聚合物膜的接触角、表面能及膜的表面形貌.     

聚集诱导发光有机氟化合物的研究进展

聚集诱导发光(aggregation-induced emission, AIE)化合物因在生物和化学传感、发光材料、显示等领域具有重要价值而备受关注.作为一类重要的功能分子,有机氟化合物在化学和材料等领域被广泛研究.汇总了具有聚集诱导发光性质的有机氟化合物,并进行了分类讨论.AIE有机氟化合物包括氟代的四苯基乙烯(TPE)衍生物、二苯乙烯基蒽(DSA)衍生物、氰基二苯基乙烯衍生物和二苯乙烯基苯衍生物等常见的AIE化合物,也包括聚合物、碳硼烷簇合物和室温磷光化合物,还有其它一些含氟结构.AIE化合物氟代后,稳定性一般会提高,氟原子参与分子间相互作用,导致聚集态的结构发生改变,从而导致发光性质的改变,如发光增强、发光波长红移(蓝移)或发光量子效率及发光寿命提高等.最后,对AIE有机氟化合物的研究前景进行了展望.     

基于聚集诱导发光“开-关”模式对肝素的定量检测EI北大核心CSCD

传统基于聚集诱导发光(AIE)开发的化学和生物传感器主要是基于荧光增强的"开"模式,该模式选择性较差,容易受到其他物质的干扰。本研究合成了一种基于AIE发光的四苯乙烯(TPE)衍生物(TPE-COOH),通过加入稀土元素Tm^(3+)使得TPE-COOH发生聚集,形成TPE-COOH/Tm^(3+)聚合物,并通过AIE原理导致TPE-COOH荧光增强,实现了"开"状态。加入肝素(Hep)后,Hep与Tm^(3+)的结合能力更强,导致TPE-COOH/Tm^(3+)聚合物分解,使得TPE-COOH处于溶解状态,体系的荧光强度逐渐降低,实现了"关"状态。本研究通过这种基于AIE的"开-关"模式实现了对Hep的定量检测。该方法对Hep检测的线性范围为1~20μmol/L,检出限为0.4μmol/L。     

聚醋酸乙烯酯的光引发可控合成——介绍一个高分子化学综合实验

本实验开展了醋酸乙烯酯的可逆加成-断裂链转移自由基聚合(RAFT),分别运用偶氮二异丁腈(AIBN)引发和可见光引发两种方式进行了聚合反应,运用核磁共振和凝胶色谱等多种手段对所得聚合物结构进行了表征与分析。通过比较AIBN引发与光引发所获得聚合物端基结构的异同,加深了学生对RAFT聚合方法原理的理解。同时,运用该方法实现了聚合物两端端基结构的高度功能化,深入体会聚合物合成设计概念。本综合实验教学不仅通过对比法加深了学生对实验原理和专业知识的理解,提升了学生创新研究能力,而且训练了学生的实验操作技能、大型仪器使用能力和结果分析能力,提升了综合素质。     

四苯乙烯衍生物的合成、性能及其对铀酰离子的荧光识别

聚集诱导发光(AIE)效应在铀酰离子痕量检测方面具有广阔的应用前景。本文以四苯乙烯(TPE)为母体,设计合成了一种TPE席夫碱类化合物T2,并对其溶液态和聚集态的光学性质进行了表征。结果表明,T2具有AIE特性。并且,当向T2中加入铀酰离子后,体系荧光发射峰从540nm蓝移到500nm,肉眼可见由黄色到黄绿色的明显颜色变化,表明化合物T2可用于检测水体中的铀酰离子。     

聚集诱导发光高分子在光学诊疗应用中的研究进展

高分子因其优异的光学特性、良好的生物相容性和分子结构易于调控等优势,在光学诊疗领域表现出巨大应用潜力.然而,传统荧光分子的聚集导致荧光淬灭现象限制了其生物应用.聚集诱导发光(AIE)分子因其聚集态高效发光的优势而备受关注.本文从AIE高分子的构建出发,重点介绍了D-A型共轭聚合物的构建策略、构-效关系以及相对于小分子的性能和应用优势,并从生物成像、肿瘤诊疗和抗菌三个方面总结了AIE高分子在光学诊疗领域的最新研究进展.生物成像方面主要总结了NIR-Ⅱ区AIE高分子在深部组织高分辨率荧光成像中的应用;肿瘤诊疗方面主要介绍了AIE高分子在光动力治疗、光热治疗及联合治疗中的应用;以及介绍了AIE高分子在细菌感染光动力治疗中的应用.最后对AIE高分子在光学诊疗领域的未来发展前景进行了展望.     

二苯乙烯基蒽聚集诱导发光材料体系的研究进展

具有聚集诱导发光(AIE)性质的有机荧光分子由于其扭曲的分子构型,在聚集态或固态表现出显著增强的荧光发射,避免了传统有机荧光分子的浓度猝灭现象,因而在光电器件、生物传感等领域有着广泛的应用.本文着重介绍了具有AIE性质的二苯乙烯基蒽(DSA)衍生物及其在高效固态发光材料、刺激响应材料、生物成像和生物与化学传感等领域的研究进展.     

Aggregation-induced multicolor luminescent nanoparticles with adaptive and fixed cores derived from brominated tetraphenylethene-containing block copolymer

Aggregation-induced emission (AIE)-active nanoparticles (NPs) exhibiting multicolor fluorescence and high-quantum yields independent of the environment are important for the further development of next-generation smart fluorescent materials. In this work, AIE-active amphiphilic block copolymers were designed and synthesized by RAFT polymerization of a brominated tetraphenylethene (TPE)-containing acrylate (A-TPE-Br). The block copolymer exhibited typical AIE effects in selective solvents, which can be explained by hydrophobic TPE aggregated in the core during micelle formation. Luminescent core–shell NPs with a crosslinked AIE core (fixed structure) were synthesized by the Suzuki coupling reaction of the bromine groups of the assembled block copolymer and boronic acid compounds. The NPs composed of TPE/thiophene crosslinked core showed green emission in both diluted state and solid state, implying the ability to fluoresce regardless of environmental changes and molecular dispersion. Multicolor luminescent NPs capable of changing color from blue to red were synthesized by changing the coupling compounds, such as anthracene for electron-rich units and benzothiadiazole for electron-deficient units. The effects of the nature of the donor and acceptor, as well as their combination (TPE/donor/acceptor sequence), on the color and fluorescent intensity of the core crosslinked NPs in the nonpolar and polar solvents, and solid state, were investigated.     

A series of poly[N-(2-hydroxypropyl)methacrylamide] copolymers with anthracene-derived fluorophores showing aggregation-induced emission properties for bioimaging

A series of new poly[N-(2-hydroxypropyl)methacrylamide]-based amphiphilic copolymers were synthesized through a radical copolymerization of a monomeric/hydrophobic fluorophore possessing aggregation-induced emission (AIE) property with N-(2-hydroxypropyl)methacrylamide. Photophysical properties were investigated using UV-Vis absorbance and fluorescence spectrophotometry. Influences of the polymer structures with different molar ratios of the AIE fluorophores on their photophysical properties were studied. Results show that the AIE fluorophores aggregate in the cores of the micelles formed from the amphiphilic random copolymers and polymers with more hydrophobic AIE fluorophores facilitate stronger aggregations of the AIE segments to obtain higher quantum efficiencies. The polymers reported herein have good water solubility, enabling the application of hydrophobic AIE materials in biological conditions. The polymers were endocytosed by two experimental cell lines, human brain glioblastoma U87MG cells and human esophagus premalignant CP-A, with a distribution into the cytoplasm. The polymers are non-cytotoxic to the two cell lines at a polymer concentration of 1 mg/mL.     

Facile construction of aggregation-induced emission molecular liquids via Piers-Rubinsztajn reaction for green fluorescent ink

Solvent-free luminescent molecular liquids(LMLs), which exhibit nonvolatile fluidic nature and active optoelectronic properties, were widely used. For further development, we introduced siloxane units into AIE molecules, designed and synthesized TPE derivatives with siloxane side chains via facile Piers-Rubinsztajn reaction. The obtained AIE molecular liquids exhibit unique photophysical properties. Compared with the obtained alkyl TPE-solids, siloxane TPE show liquid state, which proves that th...     

Tetraphenylethylene and N-isopropylacrylamide block polymer-grafted carbon dots with their application in cellular imaging

Carbon dots (CDs) grafted with block polymer of tetraphenylethylene (TPE) and N-isopropylacrylamide (CD-g-poly(TPE-block-NIPAM)) were synthesized, which are aggregation-induced emission (AIE) nanoparticles. The CD-g-poly(TPE-block-NIPAM) exhibited different fluorescence behaviors in tetrahydrofuran (THF) and water. In THF, the CD-g-poly(TPE-block-NIPAM) could fluoresce, but only from CDs, and the TPE block showed no fluorescence. The fluorescence of CDs was quenched ,and the TPE block showed AIE, when the CD-g-poly(TPE-block-NIPAM) were dispersed in water. The CD-g-poly(TPE-block-NIPAM) showed no cytotoxicity, which could be easily internalized by human breast cancer cells and human embryonic kidney cells with high fluorescence, and they can be used as fluorescent tracers for living cells.     

AIE Fluorescent Gelators with Thermo‐, Mechano‐, and Vapochromic Properties

A series of aggregation‐induced emission (AIE) fluorescent gelators (TPE‐C_n‐Chol) were synthesized by attaching tetraphenylethylene (TPE) to cholesterol through an alkyl chain. The properties of the gel, nano‐/microaggregate, and condensed phases were studied carefully. TPE‐C_n‐Chol molecules form AIE fluorescent gels in acetone and in DMF. Their fluorescence can be reversibly switched between the “on” and “off” states by a gel–sol phase transition upon thermal treatment. The AIE properties of aggregated nano‐/microstructures in acetone/water mixtures with different water fractions were studied by using fluorescence spectrometry and scanning electron microscopy (SEM). In different acetone/water mixtures, the TPE‐C_n‐Chol molecules formed different nano‐/microaggregates, such as rodlike crystallites and spherical nanoparticles that showed different fluorescence colors. Finally, the condensed phase behavior of TPE‐C_n‐Chol was studied by using polarizing microscopy (POM), differential scanning calorimetry (DSC), fluorescence spectrometry, fluorescence optical microscopy, and wide‐angle X ray scattering (WAXS). The clover‐shaped TPE unit introduced into the rodlike cholesterol mesogen inhibits not only the formation of a liquid‐crystal phase but also recrystallization upon cooling from the isotropic liquid phase. Very interestingly, TPE‐C_n‐Chol molecules in the condensed state change their fluorescence color under external stimuli, such as melting, grinding, and solvent fuming. The phase transition is the origin of these thermo‐, mechano‐, and vapochromic properties. These findings offer a simple and interesting platform for the creation of multistimuli‐responsive fluorescent sensors.     

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.     

Fabrication of fluorescent surface relief patterns using AIE polymer through a soft lithographic approach

A new aggregation‐induced emission (AIE) active polymer (PS‐TPE) with high tetraphenylethene (TPE) loading density was synthesized. The synthesized polymer showed significant AIE properties, good solubility and high thermal stability. Soft‐lithographic contact printing process by using photoinduced surface relief structures on azo polymer film as masters and duplicated PDMS elastomer as stamps was used to fabricate fluorescent PS‐TPE patterns. Various fluorescent structures with high contrast including surface relief gratings, periodically dotted patterns, and quasi‐crystal structures can be easily fabricated through this approach. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1838–1845     

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.     

Mapping Live Cell Viscosity with an Aggregation‐Induced Emission Fluorogen by Means of Two‐Photon Fluorescence Lifetime Imaging

Intracellular viscosity is a crucial parameter that indicates the functioning of cells. In this work, we demonstrate the utility of TPE‐Cy, a cell‐permeable dye with aggregation‐induced emission (AIE) property, in mapping the viscosity inside live cells. Owing to the AIE characteristics, both the fluorescence intensity and lifetime of this dye are increased along with an increase in viscosity. Fluorescence lifetime imaging of live cells stained with TPE‐Cy reveals that the lifetime in lipid droplets is much shorter than that from the general cytoplasmic region. The loose packing of the lipids in a lipid droplet results in low viscosity and thus shorter lifetime of TPE‐Cy in this region. It demonstrates that the AIE dye could provide good resolution in intracellular viscosity sensing. This is also the first work in which AIE molecules are applied in fluorescence lifetime imaging and intracellular viscosity sensing.     

From Dark to Light to Fluorescence Resonance Energy Transfer (FRET): Polarity‐Sensitive Aggregation‐Induced Emission (AIE)‐Active Tetraphenylethene‐Fused BODIPY Dyes with a Very Large Pseudo‐Stokes Shift

The work presented herein is devoted to the fabrication of large Stokes shift dyes in both organic and aqueous media by combining dark resonance energy transfer (DRET) and fluorescence resonance energy transfer (FRET) in one donor–acceptor system. In this respect, a series of donor–acceptor architectures of 4,4‐difluoro‐4‐bora‐3a,4a‐diaza‐s‐indacene (BODIPY) dyes substituted by one, two, or three tetraphenylethene (TPE) luminogens were designed and synthesised. The photophysical properties of these three chromophore systems were studied to provide insight into the nature of donor–acceptor interactions in both THF and aqueous media. Because the generation of emissive TPE donor(s) is strongly polarity dependent, due to its aggregation‐induced emission (AIE) feature, one might expect the formation of appreciable fluorescence emission intensity with a very large pseudo‐Stokes shift in aqueous media when considering FRET process. Interestingly, similar results were also recorded in THF for the chromophore systems, although the TPE fragment(s) of the dyes are non‐emissive. The explanation for this photophysical behaviour lies in the DRET. This is the first report on combining two energy‐transfer processes, namely, FRET and DRET, in one polarity‐sensitive donor–acceptor pair system. The accuracy of the dark‐emissive donor property of the TPE luminogen is also presented for the first time as a new feature for AIE phenomena.