Design of thorn-like micro/nanofibers: fabrication and controlled morphology for engineered composite materials applications

One of the most important aspects to take into account when dealing with composite materials is the filler-matrix interaction. This is particularly true in the case of nanofiber-reinforced composites. Here, we designed a new 3D architecture: growing thorns on an electrospun nanofiber surface, aiming to strengthen the fiber-matrix adhesion in engineered composite materials. The novel thorn-like fiber, composed of polyarylene ether nitriles (PEN) "stems" and iron phthalocyanine (FePc) "thorns", was prepared by combining electrospinning and temperature-induced self-assembly. Especially, the FePc thorn-like structures could be grown on PEN nanofibers by a post-temperature treatment, and the lengths of the thorns could be finely controlled by the processing time and temperature, respectively. More importantly, after the thorn-like fibers were embedded into an epoxy resin, the thorns could tie molecules and interlock with the surrounding epoxy resin. The flexural properties of composites reinforced with these thorn-like fibers were further increased in comparison with that of neat and untreated fiber-reinforced epoxy resin, respectively. Thus, this functional fiber can be used as an effective composite reinforcement to polymer resins.