It is widely acknowledged that the integrity of the fiber-to-matrix interface inherent to carbon fiber reinforced composites has scope for improvement. One promising and highly-researched strategy is the use of surface manipulation of carbon fibers to enhance their mechanical performance under shear. The complexity of commonly used surface treatments, such as plasma and oxidative etching, Requires modification of existing manufacturing infrastructure and thus their broad adoption in a manufacturing context has been limited. Herein we show that simply impregnating the carbon fibers with aryl diazonium salts and subjecting them to external stimuli, such as mild heating (100 °C), can induce surface modification which can deliver improvements of up to 150% in interfacial shear strength (IFSS) in epoxy resins. Interrogation of the fiber-to-matrix interface using molecular dynamics simulations suggests that the surface grafted molecules imparts a ‘dragging effect’ though the polymer phase and that the surface concentration of these compounds is critical to enhancing IFSS. This process obviates the practical limitations of current functionalization procedures for carbon fibers and requires infrastructure that is already routinely available on fiber manufacturing lines.

众所周知，碳纤维增强复合材料固有的纤维与基质界面的完整性有待改进。一种有前途且经过高度研究的策略是使用碳纤维的表面处理来增强其在剪切作用下的机械性能。诸如等离子体和氧化蚀刻之类的常用表面处理的复杂性要求修改现有的制造基础设施，因此限制了它们在制造环境中的广泛采用。本文中我们表明，仅用芳基重氮盐浸渍碳纤维并使之经受外部刺激，例如温和的加热（100°C），就可以诱导表面改性，从而可以提高界面剪切强度（IFSS）高达150％在环氧树脂中。使用分子动力学模拟对纤维与基质的界面进行询问表明，表面接枝的分子通过聚合物相赋予了“拖曳效应”，并且这些化合物的表面浓度对于增强IFSS至关重要。该过程消除了碳纤维当前功能化程序的实际限制，并且需要在纤维生产线上已经常规可用的基础设施。