Simultaneous exfoliation and functionalization of MoS2 nanosheets by molecular-designed poly(ionic liquid): Integrated interfacial crosslinking effect for mechanical and flame retardance enhancement of polyacrylonitrile composite fiber

Abstract Two dimensional MoS2 nanosheet is a promising nanofiller for the improvement of polymer properties, yet a significant challenge lies in scalable preparation of MoS2 nanosheets with tailor-made surface to form good compatibility with polymer. Herein, a carboxyl-rich poly(ionic liquid)-PCMVIm is molecularly designed to mediate the exfoliation and functionalization of MoS2 nanosheets. On the one hand, the immobilized PCMVIm strengthens the interfacial interactions between MoS2 and PAN chains by forming hydrogen-bonding interactions, resulting in a 55% and 70.9% increase in tensile strength and elongation at break of 2 wt% PCMVIm-MoS2/PAN composite fiber. On the other hand, the PCMVIm-MoS2 initiates the intermolecular cyclization of PAN via ionic mechanism and induces the production of MoS2-bridged graphitic nano-barrier networks, which significantly decrease the PHRR, PSPR and COP of 2 wt% PCMVIm-MoS2/PAN composite fiber by 48.7%, 51.4% and 63.5%, respectively.