Ultrasound-assisted electrochemical grafting of diethylenetriamine onto carbon fiber for enhancing interfacial performance of carbon fiber reinforced epoxy composites

Abstract

The interfacial performance of carbon fiber reinforced polymer composites (CFRPs) is critically determined by the fiber-matrix adhesion. Recent advances highlight that polyamine molecules, such as diethylenetriamine (DETA), with multiple active sites, can form covalent bonds with resin molecules, effectively establishing a covalent-bonded interphase and thereby enhancing interfacial adhesion. However, the grafting efficiency of DETA is often constrained by its inherent steric hindrance and low reactivity, which limit its electrochemical grafting onto the relatively inert carbon fiber (CF) surfaces. Herein, an ultrasound-assisted electrochemical method was developed that can achieve efficient DETA grafting onto CF in 90 s. The U-o-CF@DETA exhibits superior surface properties, attaining a high nitrogen content of 21.03 at.% and optimal surface energy of 54.50 mN m⁻¹. When incorporated into epoxy resin (EP) matrix, the composite has an outstanding interlaminar shear strength (ILSS) of 121.24 ± 2.52 MPa. Mechanistic investigations conclusively demonstrate that the introduction of ultrasound, through its cavitation energy and the provision of OH radicals, is pivotal in boosting the extent of polyamine grafting onto the CF surface. This work provides an efficient and mild strategy of preparing surface-aminated carbon fibers (CFs) for the fabrication of high-performance CFRPs with superior interfacial properties.

Graphical Abstract