Ghafoor Bilal, Schrekker Henri Stephan, Amico Sandro Campos
PPGE3M, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, RS, Brazil.
Laboratory of Technological Processes and Catalysis, Institute of Chemistry, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, RS, Brazil.
Molecules. 2022 Oct 18;27(20):7001. doi: 10.3390/molecules27207001.
A multifunctional designing approach is of great importance for advanced composite applications. This study assessed the use of ionic liquids (ILs) to modify the surface of carbon fiber (CF) and impart multifunctional characteristics to it. For that, ethanolic solutions of different ILs, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, 1-butyl-3-methylimidazolium chloride and 1-(2-hydroxyethyl)-3-methylimidazolium chloride, at different concentrations, were used to treat the CF. Fourier-transform infrared spectroscopy confirmed the presence of IL on the CF surface. The contact angle for 1% / IL-treated CF and DGEBA epoxy decreased by up to 35%, corresponding to an increase in surface energy of fiber, accompanied by an increase of 91% in interfacial shear strength. These enhancements were achieved with the hydroxy-functionalized IL, showing the tunability of CF properties through the -imidazolium substituent. An increase in crystallite size along the basal plane was also found due to the ordering of the graphitic structure on the surface. Moreover, there was a decrease in electrical resistivity of 77%. In all, the imidazolium ILs were considered a promising approach to induce multifunctional characteristics, namely enhanced interfacial strength and electrical conductivity, to unsized CF, which can also be beneficial for recycled fibers without deteriorating their inherent surface properties.
一种多功能设计方法对于先进复合材料应用至关重要。本研究评估了使用离子液体（ILs）来修饰碳纤维（CF）表面并赋予其多功能特性。为此，使用不同浓度的不同离子液体（1-丁基-3-甲基咪唑双（三氟甲基磺酰）亚胺、1-丁基-3-甲基咪唑氯盐和1-（2-羟乙基）-3-甲基咪唑氯盐）的乙醇溶液来处理碳纤维。傅里叶变换红外光谱证实了碳纤维表面存在离子液体。1%离子液体处理的碳纤维与二缩水甘油醚二苯醚环氧树脂的接触角降低了35%，这对应于纤维表面能的增加，同时界面剪切强度提高了91%。这些增强效果是通过羟基官能化离子液体实现的，表明通过咪唑取代基可以调节碳纤维的性能。由于表面石墨结构的有序排列，还发现沿基面的微晶尺寸有所增加。此外，电阻率降低了77%。总之，咪唑离子液体被认为是一种有前景的方法，可赋予未上浆碳纤维多功能特性，即增强的界面强度和导电性，这对于回收纤维也有益，且不会损害其固有表面性能。
