Multifunctional paper-like materials containing metal oxide nanofibers are important for flexible electronics and other redox-based applications, but are often prone to mechanical failure. This work presents the coassembly of V2
nanofibers (VNFs) in a dual?fiber approach together with cellulose nanofibers to produce tough (0.26 MJ m−3
), but strong (250 MPa) flexible hybrid materials. Indeed, nanotensile tests reveal a significant increase in toughness (200%) and strength (85%) of the hybrid films as compared to pristine VNF films. The microstructure of the films shows a transition from an anisotropic texture for the single-component films to an isotropic, entangled network in case of the hybrid films, which facilitates effective fracture resistance mechanisms. The flexible hybrid films display high electrical conductivity (0.2 S cm−1
) and elastic properties originating from V2
nanofibers with excellent toughness and transparency endowed by the cellulose nanofibers. The self-supported hybrid films show reversible electrochromic behavior without the need for common substrates such as conducting indium tin oxide glass. It is conceivable that these self-supported films can be exploited in the future in smart, flexible optoelectronic devices.
Adv. Func. Mater. 2018
Schematic overview of the coassembly of VNF and CNF. a,b) AFM topology images of single 2w-VNF and CNF, respectively. c) Drawings of the respective fiber surfaces, indicating functional groups and possible hydrogen bond (blue dashed lines) formation between the fibers. d) Schematic illustration of the VNF and CNF coassembly from aqueous suspension. e) Digital image of the resulting free-standing hybrid films with 17, 50, and 83 wt% CNF, respectively.