微胶囊技术在粘接涂层自修复中的应用

微胶囊技术是21世纪重点研究开发的高新技术之一,用途广泛。将其与粘接技术相结合,不仅增加产品的附加值更是获得新特性胶粘剂的新途径。本文简要介绍了微胶囊技术在粘接涂层自修复中的应用原理及研拓进展。指出了其未来研发的难点、方向。,     

自修复微胶囊及其防护涂层应用研究进展

随着自修复技术的不断发展,微胶囊在防护涂层等领域日益表现出突出的应用优势。文中综述了单壁、双壁自修复微胶囊的配方设计与结构性能以及微胶囊的模拟仿真研究现状,综述了以异氰酸酯、环氧树脂、缓蚀-腐蚀抑制剂、植物油为修复剂的自修复微胶囊在防护涂层中的应用研究进展,总结了现有微胶囊自修复材料存在的问题,提出了将自修复微胶囊与分子动力学模拟相结合的研究方法,希望通过该方法建立微胶囊宏微观结构与性能的关联性规律,实现对微胶囊自修复机理的深入探索与研究。     

仿生自修复防腐涂层的研究进展

介绍了实现材料仿生自修复功能的技术方法,在分析影响材料自修复效率因素的基础上,总结了选择微胶囊和修复剂体系应遵循的原则,综述了自修复防腐涂层中的最新研究成果,并指出自修复涂层目前存在的问题及今后研究的方向。     

脲醛树脂胶黏剂的制备及其对木质乐器裂纹涂层性能的影响研究

自修复微胶囊作为一种可抑制木质乐器表面水性涂层微裂纹的新型有效途径,在音乐乐器涂料修复方面具备广阔的应用前景。对此,文章简述了树脂基微胶囊修复技术原理与研究现状,探究了脲醛树脂胶黏剂的制备与改性,以改性后的脲醛树脂胶黏剂为壁材、环氧树脂为芯材制备了微胶囊,添加到水性丙烯酸木器涂料中形成木器水性涂层,研究微胶囊的添加对木器水性涂层性能的影响。结果表明：脲醛树脂包覆环氧树脂微胶囊的芯壁材质量比为0.83∶1时,微胶囊分散均匀、形貌较好;在水性涂层中添加10%的微胶囊,水性涂层的综合性能较好;预制划痕试验表明,微胶囊含量为10%时,木器水性涂层裂纹的愈合程度较好。     

自修复防腐涂层对海水中Q235钢耐蚀性能的电化学影响规律研究

制备用于潮湿环境中的自修复微胶囊及防腐涂层。利用扫描电镜观察微胶囊形貌,通过热重分析,获得其热稳定性数据。使用激光粒度分析仪测试其粒径分布规律。将其作为填料制成埋植型自修复防腐涂层,涂敷于Q235钢表面,采用电化学阻抗谱(EIS)研究其在海水中不同浸泡周期的腐蚀行为。结果表明在防腐涂层保护下,自修复微胶囊有阻挡海水渗透涂层的作用。微胶囊中的修复剂有填补涂层空缺的作用,增强了阻挡海水与Q235钢的接触作用。制备的自修复涂层具有修复划痕的功能。交流阻抗图表明该涂层能增强耐蚀性能。     

月桂酸微胶囊自修复涂层的制备及其防腐性能研究

主要针对碳钢基体,采用微胶囊包覆缓蚀剂技术以实现涂层的自修复性能。以脲醛树脂为壁材,月桂酸为芯材,采用两步法合成自修复微胶囊,并研究不同温度、pH、搅拌速度等工艺条件对微胶囊合成及结构的影响,优化合成工艺。将所合成的微胶囊添加在环氧树脂中,在碳钢表面制备涂层。结果表明:在合成温度60℃左右,pH 3～4,搅拌速度200 r/min时可以得到表面致密,粒径均匀的微胶囊;环氧涂层中加入微胶囊后,涂层的防护性能得到提高,具有明显的自修复性能。     

用于自修复涂料的微胶囊的研制

通过试验确定了用于自修复涂料的微胶囊制备工艺条件,成功制备了微胶囊产品。采用多种检测手段对微胶囊进行表征,通过FT-IR确定微胶囊结构,利用SEM确定微胶囊为球状结构,平均粒径50μm;采用水性羟基丙烯酸树脂作为主体,配合水性异氰酸酯固化剂,添加适量的助剂,再加入所制备的微胶囊,得到了微胶囊基水性涂料。采用光学显微镜对涂层进行观察发现,微胶囊可均匀分散在涂层中,无团聚现象。对涂层性能测试结果表明,微胶囊的加入对涂层的性能无明显不利影响;通过实验验证发现,对自修复涂层进行破坏,经过12 h的自修复,划伤处开始愈合,达到3级效果,具有良好的自修复功能。     

微胶囊修复技术在涂料中的应用研究

首先进行微胶囊功能粒子的合成，并利用光学显微镜、扫描电镜、热重、傅里叶变换红外光谱仪等对微胶囊结构及性能进行系统研究。然后将其添加到涂层中，探究其添加量和分散效果，制备了原位智能修复防腐涂层。研究了智能涂层在常压和压力交变条件下的自修复性能和防腐性能。结果表明：微胶囊在涂层中分散均匀，光学显微镜下可见涂层划痕处有聚合物产生。因此，涂层划痕处形成新的保护层，起到良好的自修复防腐蚀作用。     

自修复智能涂料研究进展:概念、作用机理及应用

介绍了自修复涂料的基本概念、自修复作用原理,重点介绍了目前发展较快的几种自修复涂层,包括微胶囊自修复涂层、液芯/中空纤维自修复涂层、氧化还原反应自修复涂层、可逆反应自修复涂层和形状记忆自修复涂层。同时,对目前自修复涂料在混凝土涂层、防腐涂层、汽车涂料和3C产品等领域的应用现状进行了综述。最后,对自修复涂料未来的发展和应用前景进行了展望。     

硅烷改性环氧树脂自修复微胶囊的制备及应用

采用硅烷偶联剂γ-（2,3-环氧丙氧基）丙基三甲氧基硅烷（KH-560）对环氧树脂E-51进行改性,并以此为芯材,三聚氰胺-脲醛树脂（MUF）为壁材,原位聚合法合成微胶囊,探讨了微胶囊制备工艺,并用光学显微镜（OM）、扫描电子显微镜（SEM）、红外光谱仪（FTIR）、热重分析仪（TGA）等对其表面形貌、化学结构及热性能等进行了表征和测试;之后将改性后的微胶囊应用到自修复环氧树脂涂层中,考察了自修复涂层的力学性能和电化学性能。结果表明,当芯壁比为1.5：1、乳化剂质量分数为1.4%时,微胶囊为规则球形,表面粗糙、致密,大小均匀,平均粒径约为100μm,具有良好的热稳定性。当涂层中改性微胶囊质量分数为3%时,涂层的拉伸强度、弯曲强度、黏结强度及冲击强度均较高,且其较未改性微胶囊自修复涂层分别提高了14.9%、14.3%、16.0%和9.6%;与未改性微胶囊自修复涂层相比,改性微胶囊自修复涂层的电化学性能增强,且电化学阻抗值显著提高。     

异氰酸酯型微胶囊自修复涂料的研究进展

介绍了微胶囊自修复涂料种类、异氰酸酯型微胶囊自修复涂料的修复机理以及微胶囊自修涂料自修复效果的评价方法。综述了IPDI型、HDI型微胶囊自修复涂料的研究进展。     

自修复超疏水多功能协同作用涂层研究进展

自修复超疏水涂层是近年来多功能涂层研究的热点之一。文中总结了超疏水自修复涂层的修复机理,包括表面形貌的恢复和低表面能物质的补充。表面形貌的恢复可采用动态化学键和气体补偿来实现;低表面能物质的补充依靠在外界条件刺激下表面能驱动底层的低表面能物质迁移至涂层表面。目前有利用形状记忆合金实现大尺度结构损伤自修复、减少对外界刺激依赖实现自主自修复进程、利用分子结构设计自修复、多层光滑浸渍多孔表面(SLIPS)设计自修复等新的研究方向。同时介绍了自修复超疏水性能结合其他功能的多功能协同作用涂层的应用,包括超疏水自修复多功能纤维、超疏水防腐蚀自修复涂层和超疏水导电自修复涂层,各个功能间不是简单的叠加而是协同作用使涂层整体性能达到最佳,这为多功能涂层的设计提供了新思路。最后展望了自修复超疏水涂层的发展方向。     

Application of EIS and EN techniques to investigate the self-healing ability of coatings based on microcapsules filled with linseed oil and CeO2 nanoparticles

Microcapsules with urea–formaldehyde as the shell and linseed oil as the healing agent were synthesized by a previously reported procedure. Two kinds of synthesized microcapsules, without and with CeO₂ nanoparticles, were separately added to the epoxy resin coatings. The epoxy coatings containing microcapsules were applied on carbon steel, and their self-healing effect was investigated in 0.5 M HCl solution. The amount of the released healing agent that filled up the scratch was estimated by scratch filling efficiency (SFE). The SFE values are only the theoretical estimates of the self-healing performance. The scratch sealing efficiency (SSE), which is a measure of corrosion protection performance of the damaged coating, can be measured by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques. For sake of an optimum self-healing system, two series of coatings, with and without nanoparticles, were prepared by using different microcapsule concentrations: 5, 10, 15 and 20 wt%. For comparison, a coating without microcapsules was also prepared. The coated samples with 5% microcapsule concentration, due to the low amount of released linseed oil, could not properly repair the artificial scratch. In contrast, when the microcapsule concentration was equal to or higher than 10% the volume of the released linseed oil was enough to seal the scratch. However, the coating sample containing 15% nanoparticle-loaded microcapsules was the optimum self-healing coating because it showed comparable SSE values to those of samples containing 20% microcapsule concentration in spite of its lower microcapsule concentration. The EN method was employed as a complementary quantitative technique to study the self-healing behavior of coatings. The calculation of the amount of noise charges using the standard deviation of partial signal (SDPS) plots arising from wavelet analysis made it possible to obtain the SSE values of the coatings. The good agreement between EIS and EN results indicates that the EN technique, as well as the EIS method, can be used successfully for the self-healing evaluation.     

Microcapsule-based self-healing anticorrosive coatings: Capsule size,coating formulation,and exposure testing

Self-healing coatings is a rapidly growing research area, where focus has mainly been on development of new approaches to the mechanism of self-healing. However, there is a growing need for investigation of practical issues related to formulation, application, and testing of true self-healing coatings. In this work, ways of reducing the size of poly(urea–formaldehyde) microcapsules, filled with linseed oil and intended for a microcapsule-based self-healing anticorrosive coating (above water exposure), are explored. The influence of microcapsules on epoxy coating performance is also studied. The actual self-healing effect was not part of this work. The synthesis parameters investigated are stirrer geometry, agitation rate, temperature, and stabilizer concentration. It was found that an increase in stirring rate, correct choice of temperature, and a high stabilizer concentration all caused a decrease in microcapsule size but were accompanied by excessive formation of nanoparticles. Thus, isolation of too large microcapsules has been performed by filtration utilizing a novel low-energy fluoropolymer-coated steel sieve. An estimation of the critical pigment (microcapsule) volume concentration (CPVC) was conducted using gloss measurements and a PVC ladder and found to be about 30 vol%. Due to the rather large capsules used (relative to the coating thickness), the low CPVC value can probably be ascribed to a fairly low packing efficiency in the coating, but this needs to be confirmed. Coating performance was evaluated using salt spray exposure and impact testing. Results of the impact testing showed that addition of microcapsules to a binder matrix did not compromise resistance of the coating to mechanical damage and led to formation of fewer and shorter cracks compared to a filler-containing coating. Flaking of the coating was also reduced. Results of the salt spray testing (3 weeks exposure) showed that with an increase of microcapsule content, in the interval 30–50 vol%, the extent of corrosion and potential coating delamination decreased and was identical to that of a full commercial anticorrosive coating.     

Salt spray and EIS studies on HDI microcapsule-based self-healing anticorrosive coatings

Anticorrosive property of hexamethylene diisocyanate microcapsule-based self-healing coatings was systematically investigated by salt spray and EIS measurements. The influences of microcapsule diameter, weight fraction and coating thickness on the anticorrosive performance of the scratched samples were studied under salt spray condition, which revealed the thicker coatings with larger microcapsules at 10 wt.% demonstrated the best anticorrosion behavior. Additionally, the kinetics of self-healing process characterized by EIS measurement was parametrically analyzed in an equivalent circuit when the scratched coating was exposed to salt solution. A simplified model was established to explain the influences of these factors with consideration of scratch dimension.     

High-performance self-healing anticorrosion epoxy coating based on microencapsulated epoxy-amine chemistry

Attributed to the merits of excellent material compatibility, healing performance, and long-term stability, the self-healing system based on microencapsulated epoxy-amine chemistry is a potentially practical self-healing system for both structural and functional materials. Herein, based on the microencapsulated epoxy-amine chemistry, a self-healing anticorrosion coating was successfully developed. This self-healing coating system was modeled theoretically to explore the factors that influence the crack filling and the self-healing anticorrosion function. The established quantitative relationship shows that the filling depth of the crack in the coating is proportional to the microcapsule parameters and coating thickness, but inversely proportional to the crack width. Based on the above theoretical model, the effects of various parameters on the anticorrosion performance were experimentally studied. The actual filling of small in-situ cracks (<100 μm) generated by impact damage was semi-quantitatively characterized using scanning electron microscopy (SEM). The filling behavior is consistent with the theoretical modeling. After being healed at room temperature for 2 days upon impact damage, the formulated self-healing coatings were subjected to accelerated corrosion tests in 10 wt% sodium chloride (NaCl) solution for 2 days to observe their anticorrosion behavior. Compared to the neat epoxy coating, all the formulated self-healing epoxy coatings show evident anticorrosion function. Good self-healing anticorrosion performance was achieved by adding 10.0 wt% microcapsules with a size of 100–150 μm to the coating with a thickness of 300 μm. The results of this investigation laid a theoretical and technical foundation for the further development of both the self-healing chemistry and the self-healing anticorrosion coating.     

微胶囊技术及其在复合材料中的应用

介绍了微胶囊技术的概念及其种类,归纳总结了微胶囊的表征方法。根据微胶囊近年来的研究,重点阐述了微胶囊技术在聚合物基复合材料损伤自修复过程中的应用研究。     

Self-healing coatings for steel

The efficacy of a “self-healing” corrosion protection coating system for use on steel enclosures for outdoor equipment has been investigated using urea formaldehyde microcapsules (50–150 μm in diameter) containing several types of film forming compounds (healants) and corrosion inhibitors mixed into commercially available coatings systems. Five different types of inhibitors/film formers were tested, and three different techniques for application of the coatings with microcapsules were evaluated. Laboratory tests showed that when the coating system was damaged by abrasion, the microcapsules released the film forming and corrosion inhibiting compounds. Steel substrates coated with these self-healing systems were scribed and laboratory tested according to ASTM D 5894. Undercutting at the scribe (ASTM D 1654) was reduced by using microcapsules containing self-healing compounds. Growth of coating damage at the scribe was arrested in self-healing coatings with all microcapsule formulations compared to control samples. The performance of some microcapsules evaluated in this study was found to be dependent on the method of application.     

Antibacterial self-healing anticorrosion coatings from single capsule system

It is highly desirable to develop self-healing anticorrosion coatings with enhanced antibacterial function to prevent the scratched area to be fouled or corroded in harsh environments. Herein, we report antibacterial self-healing anticorrosion coatings via the simple incorporation of the easily synthesized single polymer microcapsule system. Well-defined polymer microcapsules containing isophorone diisocyanate (IPDI) as a healing agent and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT) as antibacterial molecules were synthesized by one-pot polymerization. The diameter and core fraction were around 30 μm and 90%, respectively. The active DCOIT content in the core material could be precisely controlled by adjusting the DCOIT/IPDI feeding ratio. The DCOIT/IPDI microcapsules-embedded protective coating exhibits an adaptive self-healing anticorrosion property, as shown by electrochemical test under the condition of the salt-water immersion. Furthermore, the self-healing coating showed efficient antibacterial function against Escherichia coli and Pseudomonas aeruginosa, which is due to the released active biocide molecules on the damaged surfaces. In contrast to other systems, this single capsule system without any catalyst is perspective for extending the service time of the antibacterial self-healing materials in harsh environment.