GAP基自修复粘结剂的制备及性能

为了延长粘结剂的储存寿命,采用一步法将具有可自修复性能的双硫官能团引入叠氮粘结剂中,首次合成了具有自修复性能的聚叠氮缩水甘油醚(GAP)基自修复粘结剂。通过傅里叶红外光谱(FTIR)、X射线衍射(XRD)和光学显微镜对其结构和表面形貌进行表征,在此基础上,通过自修复前后拉伸强度的变化,考察了不同自修复温度和不同自修复时间下的自修复效率。结果显示:合成的GAP基自修复粘结剂具有聚氨酯结构,60℃下24 h后表面裂纹基本愈合完全。提高自修复温度和延长自修复时间,均有助于提高体系的自修复效率。同时随着交联剂质量分数的增加,自修复效率先提高后降低,其中交联剂质量分数为8%的配方,自修复效率可达98.2%,相对于自修复效率为61.7%的对比样,表明双硫官能团的引入能够提高体系的自修复效率。     

自修复混凝土技术的现状与发展

自修复混凝土（SHC）技术是一种新型混凝土修补技术,利用混凝土中添加的自修复剂或微生物等使得混凝土中的裂缝自行愈合,从而延长混凝土使用寿命,减少环境污染和资源浪费。本文介绍了自修复混凝土技术的原理、发展、研究热点及未来的趋势和应用前景。     

基于碳纳米管/聚乙烯醇的自愈合柔性电极

对多壁碳纳米管 (MWCNT) 进行回流酸处理，增加其表面活性获得羧基化多壁碳纳米管(CMWCNT)，结合聚乙烯醇 (PVA) 形成多功能导电水凝胶。借助CMWCNT表面羧基活性基团，与多重络合、纠缠的PVA链形成广泛氢键，构建CMWCNT-PVA水凝胶分层网络。通过丝网印刷工艺，制备CMWCNT-PVA自愈合柔性电极，该电极具有高电导率(35.1 S/m) 、高机械强度 (2000次循环弯曲) 和约10秒的自愈合特性，愈合后电路中，在大变形下也保持优异导电性和稳定性，且由柔性电路设计制备的发光二极管阵列，能够呈现HF发光图案。该自愈合柔性电极为柔性电路发展提供一种新的策略，对拓展电子皮肤、软体机器人和可穿戴设备等在人机交互中的应用具有重要科学意义。     

Intelligent self-healable electroactive carboxymethyl cellulose hydrogel containing conductive polythiophene and acid hydrolyzed cellulose

Self-healable electroactive carboxymethyl cellulose/polythiophene/acid hydrolyzed cellulose (CMC/PTh/AHC) hydrogels were successfully fabricated. AHC particles dispersed well in the CMC matrix improving hydrogels thermal stability. The electro-responsive performance of the hydrogels was investigated with respect to bending angle and bending sensitivity. The results showed that under an applied electric field, the CMC/PTh/AHC hydrogels bend toward a cathode electrode. In addition, the electroactive performance of the hydrogels decreased with increased AHC content. The CMC/PTh/AHC10 (10 wt.% AHC) hydrogel exhibited the shortest induction time (τ_ind) of 3.35 ± 0.56 s. For self-healing, it was found that the hydrogel with addition of 2 wt.% AHC had the highest self-healing efficiency on both tensile strength and elongation at break (93.37 ± 3.17% and 99.35 ± 12.11%, respectively). While the self-healing efficiency on bending angle was 82.73 ± 14.55%. The results demonstrated that the properties of the CMC/PTh/AHC2 hydrogel were close to its original properties after healing for 24 h. The results demonstrated that the CMC/PTh/AHC hydrogel can be utilized as an actuator or artificial muscle using electrical stimulus.     

Room temperature-responsive poly(vinyl hydroxyalkyl ether-alt-dialkyl maleate)-based vitrimers with dynamic boronic ester bonds

Dynamic B O bonds are often applied to fabricate reversible-cross-linking and reprocessable polymer networks due to their high thermodynamic stability and kinetic tunability. However, it is still difficult to tailor boronic ester polymers, which have both excellent mechanical and self-healing properties in the absence of external stimuli. To address the above challenge, a range of room-temperature self-healable vitrimers are prepared by the reactions of various poly(vinyl hydroxyalkyl ether-alt-dialkyl maleate) copolymers and 1,4-phenyldiboronic acid. The dynamic cross-linking networks offer the as-prepared vitrimers superior mechanical properties and thermostability. Because of the presence of dynamic boronic ester bonds, the networks also demonstrated self-healing (the tensile strength recovered to 83% after 3 days at room temperature) and reprocessing capabilities (no significant change in tensile strength after thrice process recycles). Moreover, the vitrimers have potential as promising damping materials with wide temperature windows around room temperature. For example, the vitrimer of poly(ethylene glycol monovinyl ether-alt-dibutyl maleate) and 1,4-phenyldiboronic acid demonstrates its tanδ_max 1.18, T_g = 6.2°C and effective damping temperature range is from −16.4 to 48.5°C.     

Preparation of light-responsive block copolymer modified cellulose nanocrystal@polydopamine particle and its application in fluorinated polyacrylate film

Light-responsive cellulose nanocrystal@polydopamine (CNC@PDA) modified fluorinated polyacrylate was synthesized by Pickering emulsion polymerization with light-responsive block copolymer modified CNC@PDA as stabilizer. The epoxy groups in poly(acrylic acid-co-acrylamide)-b-poly(glycidyl methacrylate)-b-poly(hexafluorobutyl acrylate-co-coumarin) amphiphilic triblock copolymer reacted with the hydroxyl and amino groups on the surface of CNC@PDA to form the modified CNC@PDA. The successful preparation of modified CNC@PDA was confirmed by means of FT-IR, XRD, TG, UV–Vis, surface tension measurement, and X-ray photoelectron spectroscopy (XPS) techniques. The results showed that the modified CNC@PDA had light-responsive and amphiphilic properties, and could be used as stabilizer to form stable Pickering emulsion. And the influence of modified CNC@PDA dosage on emulsion polymerization and film performance was systematically studied. The latex particle size decreased initially with increasing modified CNC@PDA dosage, from 0.6 to 1.0 wt%, and then increased. The mechanical, self-healing, and water–oil repellent properties of film were enhanced initially with increasing modified CNC@PDA dosage, from 0.6 to 1.0 wt%, and then declined. Atomic force microscope confirmed that the latex film had a rough surface. Moreover, the latex film comprising 1.0 wt% modified CNC@PDA presented not only high tensile strength (4.92 MPa), large elongation at break (657.70%), and superior oil/water repellency but also excellent self-healing property.     

自愈合凝胶在柔性传感器中的应用研究进展

自愈合凝胶具有优异的机械性能、良好的生物相容性和延长材料使用寿命功能等特性,已广泛应用在电子皮肤、柔性机器人、可穿戴设备等方面。凝胶基质结构的可调性和导电材料选择的多样性也为制备具有不同功能的柔性传感器提供了可能。该文根据交联方式、功能性类型、愈合方式和胶凝剂相对分子质量大小4种分类方式将自愈合凝胶进行了分类,并详细介绍了各种自愈合凝胶的成胶机制和性能特点。综述了自愈合凝胶在柔性传感器中力学、光电和生物方面的国内外研究现状。最后,讨论了该研究领域仍存在的问题,并对其未来发展前景及方向进行了简要展望。     

微胶囊对沥青混合料疲劳与自愈性能影响研究

微胶囊在增强沥青自愈合性能、延长沥青路面使用寿命方面具有非常大的潜力。首先,利用红外光谱定量分析方法,评价了微胶囊在沥青混合料中的存活率。然后,利用沥青黏结强度试验对含有微胶囊的沥青进行拉拔测试,借助荧光显微镜观测拉拔断面中微胶囊的激活行为。在此基础上,利用四点弯曲疲劳试验研究微胶囊对沥青混合料疲劳与自愈合性能的影响。研究结果表明,微胶囊在温拌沥青混合料的存活率可达69.87%,比在热拌沥青混合料中高9.64%。在常温条件下,微胶囊可以被沥青中的裂缝激活并释放再生剂。微胶囊对沥青混合料的初始抗疲劳性能有显著增强作用,主要因为微胶囊在施工期间和加载过程中释放出的再生剂软化了沥青,降低了沥青混合料试件的内部应力并极大程度上加速裂纹愈合。适量的微胶囊能够显著增强沥青混合料的自愈合性能,而且随着“疲劳-愈合”次数的增加,微胶囊对沥青混合料自愈合性能增强作用逐渐凸显。     

自愈组密钥分配在电动汽车通过VANET参与V2G中的应用

随着电动汽车的迅速发展,电动汽车通过结合车辆自组织网络(VANET)参与V2G(Vehicle-to-Grid)成为智能交通系统的一部分,在资源受限的VANET网络中,为了保证用户通信安全,需要给用户分发组密钥,通过自愈组密钥分发(Self-healing Group Key Distribution,SGKD)方案,解决在不可靠的VANET网络上分发和更新用于安全组通信的组密钥问题。文中采用一种基于指数算法的SGKD方案(E-SGKD),通过引入唯一会话标识符,解决了已撤销用户与新加入用户之间的共谋攻击问题。利用单向哈希链构造个人秘钥、撤销多项式和密钥更新广播数据包,因此,方案增加了最大允许撤销用户数,减少了密钥更新广播数据包的冗余。通过分析对比证明,此方案具有安全性全面、存储开销和通信开销最优等特点,并适用于资源受限的VANET网络环境。     

纺织复合材料在石油工业上的应用

叙述纺织复合材料在石油工业上的应用进展,重点介绍了三方面内容:纺织复合材料对损坏油气井套管的内衬修复应用、智能自修复纺织复合材料在油田地面工程设施或海上平台上的应用、纺织复合材料在油田设备部件上的应用。