Preparation of hierarchical carbon nanotube–carbon fiber composites with coordination enhancement

Single-walled carbon nanotubes–carbon fiber (SWNTs@CF) hierarchical fibers were prepared by electrophoretic deposition. To improve the interfacial strength between SWNTs and CF, a hexahapto-metal complex, Cr(CO) 6 , was added to the electrophoretic system to prepare hierarchical fibers (SWNTs-Cr(CO) 6 @CF). Results revealed that SWNTs covered CF surface entirely and formed a hierarchical structure. The morphology could be tailored from scattered nanotubes over forest to network by varying the deposition voltage. The hierarchical fibers were highly compatible with epoxy matrix, which could significantly increase the interfacial adhesion through interlocking epoxy matrix. Tensile properties were studied to investigate the effect of interfacial adhesion on mechanical properties of the reinforced composites. The polymeric composite, reinforced by SWNTs-Cr(CO) 6 @CF, exhibited a remarkably high tensile strength of 519 MPa with the content ratio of 1.5:1 (Cr(CO) 6 :SWNTs). The improvement was up to 193% compared to the desized CF composite and 19% compared to SWNTs@CF composite. Additionally, thermogravimetric analyses demonstrated that the SWNTs-Cr(CO) 6 @CF composite exhibited superior heat stability.