Polymeric Emissive Materials Based on Dynamic Covalent Bonds

Dynamic covalent polymers, composed of dynamic covalent bonds (DCBs), have received increasing attention in the last decade due to their adaptive and reversible nature compared with common covalent linked polymers. Incorporating the DCBs into the polymeric material endows it with advanced performance including self-healing, shape memory property, and so forth. However, the emissive ability of such dynamic covalent polymeric materials has been rarely reviewed. Herein, this review has summarized DCBs-based emissive polymeric materials which are classified according to the different types of DCBs, including imine bond, acylhydrazone bond, boronic ester bond, dynamic C-C bond, as well as the reversible bonds based on Diels–Alder reaction and transesterification. The mechanism of chemical reactions and various stimuli-responsive behaviors of DCBs are introduced, followed by typical emissive polymers resulting from these DCBs. By taking advantage of the reversible nature of DCBs under chemical/physical stimuli, the constructed emissive polymeric materials show controllable and switchable emission. Finally, challenges and future trends in this field are briefly discussed in this review.     

基于多重动态共价键的环氧类玻璃网络的制备与性能

以三羟甲基丙烷三缩水甘油醚(TTE)为基体, 2,2′-(1,4-亚苯基)-双[4-硫醇1,3,2-二氧杂戊烷](BDB)和3,3-二硫代二丙酸(DTDPA)为交联剂, 通过环氧-巯基“点击”反应和环氧-羧酸酯化反应, 制备了基于多重动态共价键(硼酸酯键、 二硫键和酯键)的环氧类玻璃网络. 利用红外光谱和拉曼光谱对其结构进行了表征, 结果表明, 环氧类玻璃中不仅存在硼酸酯键、 二硫键和酯键, 还存在可逆氢键, 并且大量氢键的存在能提高环氧类玻璃的交联度. 对所得环氧网络的热稳定性、 热机械性能和力学性能进行了测试, 并对基于多重动态共价键环氧网络进行了自修复、 焊接、 形状记忆和再加工能力测试. 结果表明, 在80 ℃下可实现网络的完全自修复、 再加工与焊接, 且焊接后样品的力学性能(拉伸强度)恢复率在80%以上, 具有优异的功能性.     

Water-Resistant and Stretchable Conductive Ionic Hydrogel Fibers Reinforced by Carboxymethyl Cellulose

Conductive ionic hydrogels (CIH) have been widely studied for the development of stretchable electronic devices, such as sensors, electrodes, and actuators. Most of these CIH are made into 3D or 2D shape, while 1D CIH (hydrogel fibers) is often difficult to make because of the low mechanical robustness of common CIH. Herein, we use gel spinning method to prepare a robust CIH fiber with high strength, large stretchability, and good conductivity. The robust CIH fiber is drawn from the composite gel of sodium polyacrylate (PAAS) and sodium carboxymethyl cellulose (CMC). In the composite CIH fiber, the soft PAAS presents good conductivity and stretchability, while the rigid CMC significantly enhances the strength and toughness of the PAAS/CMC fiber. To protect the conductive PAAS/CMC fiber from damage by water, a thin layer of hydrophobic polymethyl acrylate (PMA) or polybutyl acrylate (PBA) is coated on the PAAS/CMC fiber as a water-resistant and insulating cover. The obtained PAAS/CMC-PMA and PAAS/CMC-PBA CIH fibers present high tensile strength (up to 28 MPa), high tensile toughness (up to 43 MJ/m³), and good electrical conductivity (up to 0.35 S/m), which are useful for textile-based stretchable electronic devices.     

海藻酸动态共价交联水凝胶的制备及其自愈合性能

利用高碘酸钠氧化海藻酸得到带有醛基的海藻酸,利用水合肼与聚乙二醇反应得到末端为酰肼基的聚乙二醇,以二者为原料利用醛基与酰肼基反应形成酰腙键的动态化学反应,赋予天然生物大分子水凝胶优良的自愈性和p H响应性.通过红外光谱、核磁共振光谱、动态黏弹谱、电子万能试验机等表征了材料的结构、水凝胶的自愈合能力以及p H响应性.结果表明,该水凝胶具有良好的力学性能和自愈合能力,能够在不加热和不添加催化剂的情况下,在温和的生理环境下自发实现切口愈合.同时水凝胶具有p H响应性,在碱性环境中成凝胶,在酸性环境中则转变为溶液状态,并且这种凝胶—溶液转变可重复多次.这些优异的性能,加上简单的制备方法、良好的生物相容性将为这类材料在生物医用领域的应用提供坚实的基础.     

Self-healing,Stretchable, Temperature-Sensitive and Strain-Sensitive Hydrogel-based Flexible Sensors

Flexible hydrogels have shown promise as strain sensors in medical monitoring, human motion detection and intelligent robotics. For a hydrogel strain sensor, certain challenges need to be urgently addressed for practical applications, such as the damage caused by external effects, leading to equipment failure, and the inability to perceive ambient temperature, resulting in single functionality. Herein, a stretchable,self-healing and dual temperature-strain sensitive hydrogel, with a physically-c...     

An Organic–Inorganic Hybrid Cathode Based on S–Se Dynamic Covalent Bonds

A diphenyl trisulfide–selenium nanowire (DPTS‐Se) organic–inorganic hybrid cathode material is presented for rechargeable lithium batteries. During discharge, three voltage plateaus associated with three lithiation processes are observed. During recharge, the combination of the radicals formed upon delithiation leads to several new phenyl sulfoselenide compounds which are confirmed by HPLC‐QTof‐MS. The hybrid cathode exhibits superior cycling stability over pristine Se or DPTS as cathode alone. The first discharge shows a capacity of 96.5 % of the theoretical specific capacity and the cell retains 69.2 % of the initial capacity over 250 cycles. The hybrid cathode also shows a high Coulombic efficiency of over 99 % after 250 cycles. This study demonstrates that the combination of organic polysulfide and selenium can not only improve the utilization of active materials but also enhance the cycling performance.     

Simultaneous Chiral Fixation and Chiral Regulation Endowed by Dynamic Covalent Bonds

The construction of chiral superstructures through the self-assembly of non-chiral polymers usually relies on the interplay of multiple non-covalent bonds, which is significantly limited by the memory ability of induced chirality. Although the introduction of covalent crosslinking can undoubtedly enhance the stability of chiral superstructures, the concurrent strong constraining effect hinders the application of chirality-smart materials. To address this issue, we have made a first attempt at the reversible fixation of supramolecular chirality by introducing dynamic covalent crosslinking into the chiral self-assembly of side-chain polymers. After chiral induction, the reversible [2+2] cycloaddition reaction of the cinnamate group in the polymer chains can be further controlled by light to manipulate inter-chain crosslinking and decrosslinking. Based on this photo-programmable and dynamic chiral fixation strategy, a novel pattern-embedded storage mechanism of chiral polymeric materials was established for the first time.     

Dynamic Oxime-Urethane Bonds,a Versatile Unit of High Performance Self-healing Polymers for Diverse Applications

Oxime-urethane bond featuring with high reversibility even at room temperature and multiple reactivity is an emerging dynamic covalent bond, and has shown great potential for self-healing polymers, which are one of the most attractive development directions for next generation of polymeric materials. In this review, recent progresses on the oxime-urethane-based self-healing polymers, including their designs and applications in diverse fields such as biomedicine, flexible electronics, soft robots...     

基于离子液体和二芳基乙烯的离子凝胶的光致变色、导电、自修复及柔性传感性能

在丙烯酸聚合中原位引入4,4′-(全氟环戊烯-1,2-二基)双(5-甲基噻吩-2-甲醛)(DEA)和离子液体1-丁基-3-甲基咪唑四氟硼酸盐((BMIm)BF₄),制备了一种同时具有光致变色、导电、自黏附且具有宽温度工作区间等性能的新型离子自修复凝胶DPZI。由于(BMIm)BF₄的高热稳定性和低蒸气压,所获得的DPZI凝胶在-20～40℃较宽的温度下表现出高度稳定的机械和离子导电性能。DPZI系统中引入的Zn²⁺与—COO^- 形成动态配位键,使得凝胶具有快速的自修复能力,0.06 s即可超快恢复电阻响应;离子液体的引入同时赋予了凝胶优异的抗冻性。DPZI因光致变色单元DEA的异构化可在10 s内快速发生黄-蓝颜色可逆转变,且光致变色单元的开环/闭环异构化能够实现对凝胶导电性的调节。此外,DPZI凝胶应变/压力式传感器可迅速、精准感知人体不同部位的运动并做出相应的响应;也可对呼吸、心率、声音做出精准识别,应变灵敏度为0.2%。     

温度响应型酰腙可逆共价键水凝胶的制备及性能

首先,通过可逆加成-断裂转移(RAFT)聚合制备了丙烯酰胺(AM)、双丙酮丙烯酰胺(DAAM)和N-异丙基丙烯酰胺(NIPAM)的共聚物(PAM-co-PDAAM-co-PNIPAM);然后,使PAM-co-PDAAM-co-PNIPAM与己二酸二酰肼(ADH)反应后,得到了具有温度和pH双重响应性的水凝胶.通过核磁共...     

基于离子液体和二芳基乙烯的离子凝胶的光致变色、导电、自修复及柔性传感性能

在丙烯酸聚合中原位引入4,4''-(全氟环戊烯-1,2-二基)双(5-甲基噻吩-2-甲醛)(DEA)和离子液体1-丁基-3-甲基咪唑四氟硼酸盐((BMIm)BF₄),制备了一种同时具有光致变色、导电、自黏附且具有宽温度工作区间等性能的新型离子自修复凝胶DPZI。由于(BMIm)BF₄的高热稳定性和低蒸气压,所获得的DPZI凝胶在-20~40℃较宽的温度下表现出高度稳定的机械和离子导电性能。DPZI系统中引入的Zn²⁺与—COO^-形成动态配位键,使得凝胶具有快速的自修复能力,0.06s即可超快恢复电阻响应;离子液体的引入同时赋予了凝胶优异的抗冻性。DPZI因光致变色单元DEA的异构化可在10s内快速发生黄-蓝颜色可逆转变,且光致变色单元的开环/闭环异构化能够实现对凝胶导电性的调节。此外,DPZI凝胶应变/压力式传感器可迅速、精准感知人体不同部位的运动并做出相应的响应;也可对呼吸、心率、声音做出精准识别,应变灵敏度为0.2%。     

Self-healing Behavior of Ethylene Propylene Diene Rubbers Based on Ionic Association

To meet the increasing demand for safe, environmentally friendly and high-performance smart materials, self-healing rubbers are highly desired. Here, the self-healing performance of ethylene propylene diene monomer rubber (EPDM) is reported, which was designed by graft-polymerization of zinc dimethacrylate (ZDMA) onto rubber chains to form a reversible ionic cross-linked network. Single ionic cross-linked network and dual network, combining covalent and ionic cross-links, could be tuned by controlling vulcanization process to achieve tailorable mechanical and self-healing properties. It was found that ionic cross-linked EPDM showed a recovery of more than 95% of the original mechanical strength through a healing process of 1 h at 100 °C. The covalent cross-links could improve mechanical properties but block self-healing. Adding 50 wt% liquid rubber to “dry” EPDM could effectively enhance self-healing capability of the dual cross-linked network and the healed tensile strength could reach 0.9 MPa. A compromise between mechanical performance and healing capability could be potentially tailored by controlling vulcanization process and liquid rubber content.     

基于动态化学的自愈性水凝胶及其在生物医用材料中的应用研究展望

自愈性材料具有自我修复损伤的特点, 能够增加使用材料的安全性, 延长材料寿命, 是一种具有损伤管理性能的智能新材料. 基于动态化学的自愈性水凝胶是近来备受关注的一种自愈性材料, 由具有动态特性的交联网络构建形成. 交联作用为动态化学键, 即非共价键, 如弱相互作用的氢键、分子间作用力(范德华力)、配位作用、亲疏水作用等, 或可逆共价键, 如温和条件下可逆的亚胺键、双硫键、酰腙键等. 这种材料具有本征性的自愈性, 一方面可应对外界破坏造成的损伤, 进行自我修复. 另一方面动态化学键对多种环境刺激具有响应性, 能自我调节以适应环境变化, 为将自愈性水凝胶开发为自适性多功能智能新材料奠定了基础. 水凝胶具有优越的生物相容性以及和生物组织的相似性, 在生物医用材料中如药物控制释放、组织工程修复、生物仿生等领域发挥着越来越大的作用, 而开发具有自愈性的多功能智能水凝胶, 将进一步拓展其应用. 综述了近来基于动态化学的自愈性水凝胶的制备及其在生物医用材料领域中的应用研究.     

Solvent Electrostatic and Covalent Effects on Complexation Thermodynamics

A new method is suggested for estimating the electrostatic and covalent contributions to the standard Gibbs energy, enthalpy and entropy of complexation reactions upon transfer from water (W) to non-aqueous and mixed aqueous organic solvents (S). The equations derived for calculation of the electrostatic (temperature dependent) contributions are based on the temperature dependences of thermodynamic parameters of complexation in aqueous solution and the temperature dependence of the dielectric constant of water. These contributions correspond to the transfer process in water from T₁ = 298.15 K to a higher temperature (T₂) at which water has the same dielectric constant as does the solvent S at 298.15 K (εW(T₂) = εS(T₁)). The covalent (temperature independent) contributions are calculated at isodielectric conditions (transfer from water at T₂ to S at T₁) using the corresponding thermodynamic cycle. Application of the model to an analysis of solvent effects is demonstrated and discussed with an example given of a typical complexation reaction between K⁺ and 18-crown-6 in pure non-aqueous and water-acetonitrile mixed solvents.     

基于含POSS-dendrimer超强液晶凝胶的柔性可拉伸液晶光散射显示器

利用凝胶因子自组装可赋予凝胶网络形状、强度等的特性,设计制备了多面体齐聚倍半硅氧烷(POSS)核有机无机杂化dendrimer(POSS-G1-BOC)凝胶因子并将其引入到液晶客体分子中,获得了兼具力学性能与响应特性的超分子液晶凝胶.在系统研究该液晶凝胶的凝胶行为、响应特性、表面形貌、组装机理及力学性质的基础之上,制备了基于透明柔性可拉伸导电薄膜(PU/Ag NWs)的三明治结构液晶光散射显示器件.该器件在低电压(10 V,DC)驱动下即可实现较高对比度的显示效果,不仅可以在弯曲至曲率为0.14 cm-1的条件下使用,而且在拉伸至原始长度的120%时,仍可保持自身的电控响应特性,有望将其广泛应用于可穿戴设备、智能响应性材料等领域.     

Detection of a Covalent—Ionic Carbinolamine Intermediate in Aqueous Media by SDTLC on Silica Gel Plates

JPC – Journal of Planar Chromatography – Modern TLC - When the components of a reaction mixture cannot be quantified by UV-visible spectrophotometry, because the λmax values of...     

基于动态建构化学的自愈合水凝胶及其在生物医学领域的应用展望

自愈合水凝胶与传统水凝胶相比,经受力破坏后仍可恢复其结构和功能,具有自我修复损伤的特点,是近年来备受关注的一种智能软材料.动态建构化学概念的引入,极大地促进了多响应性动态自愈合水凝胶的发展.本文综述了近年来基于动态建构化学合成自愈合水凝胶的方法,包括多重氢键作用、疏水相互作用、亚胺键、酰腙键等,并分析探讨了影响凝胶自愈合性能的因素及其在生物医学领域的潜在应用,还对其未来的发展进行了展望.     

The Effect of Ionic Liquid Covalent Bonding to Sol‐Gel Processed Film on Ion Accumulation and Transfer

Accumulation of electroactive anions into a silicate film with covalently bonded room temperature ionic liquid film deposited on an indium tin oxide electrode was studied and compared with an electrode modified with an unconfined room temperature ionic liquid. A thin film containing imidazolium cationic groups was obtained by sol‐gel processing of the ionic liquid precursor 1‐methyl‐3‐(3‐trimethoxysilylpropyl)imidazolium bis(trifluoromethylsulfonyl)imide together with tetramethylorthosilicate on the electrode surface. Profilometry shows that the obtained film is not smooth and its approximate thickness is above 1 μm. It is to some extent permeable for a neutral redox probe – 1,1′‐ferrocene dimethanol. However, it acts as a sponge for electroactive ions like Fe(CN)₆^3?, Fe(CN)₆^4? and IrCl₆^3?. This effect can be traced by cyclic voltammetry down to a concentration equal to 10^?7 mol dm^?3. Some accumulation of the redox active ions also occurs at the electrode modified with the ionic liquid precursor, but the voltammetric signal is significantly smaller compare with the bare electrode. The electrochemical oxidation of the redox liquid t‐butyloferrocene deposited on silicate confined ionic liquid film is followed by the expulsion of the electrogenerated cation into an aqueous solution. On the other hand, the voltammetry obtained with the electrode modified with t‐butyloferrocene solution in the ionic liquid precursor exhibits anion sensitive voltammetry. This is explained by anion insertion into the unconfined ionic liquid deposit following t‐butylferricinium cation formation.     

Functional Liquid Crystal Elastomers Based on Dynamic Covalent Chemistry

The marriage of liquid crystal elastomers with dynamic covalent chemistry can be a new paradigm for the development of dynamic and intelligent polymers with versatile functionalities, which is of paramount significance for many emerging applications such as adaptive optics, soft robotics, bioinspired camouflage, 3D/4D printing technology and beyond. Read more in the Review by Wang, Feng et al. ( 10.1002/chem.202201957 )     

基于动态共价键的自愈性水凝胶及其在医学领域的应用

自愈性水凝胶作为一种新型仿生智能材料受到了科研人员的广泛关注.近年来,人们利用动态共价键、超分子作用,发展了一系列自愈性水凝胶,并将其应用于药物控释、细胞三维培养、组织工程等生物医用领域.本文总结和评述了基于动态共价键的自愈性水凝胶及这些水凝胶作为药物载体的相关研究,并展望了基于动态化学的自愈性水凝胶的未来发展.