N-P-Zn-containing 2D supermolecular networks grown on MoS2 nanosheets for mechanical and flame-retardant reinforcements of polyacrylonitrile fiber

Abstract

In this work, a novel sandwich-type hybrid denoted as MPZSN-MoS2 was constructed by the self-assembling of melamine, phytic acid and Zn2+ to grow 2D supermolecular networks (MPZSN) onto the surface of molybdenum disulfide (MoS2) nanosheet, which was applied in mechanical and flame-retardant reinforcements of polyacrylonitrile fiber. With the incorporation 2 wt% MPZSN-MoS2, the tensile strength and elongation at break of MPZSN-MoS2/PAN composite fiber were increased by 68.2% and 27.8% compared to pure PAN fiber, respectively. The initial thermal decomposition temperature (T−5%) of MPZSN-MoS2/PAN fiber was increased by 21 °C, suggesting the enhanced thermal stability. Importantly, the single MPZSN-MoS2/PAN composite fiber could not be ignited and exhibited noticeable char formation when directly exposed to a flame, while the pure PAN fiber caught fire immediately and burned out. Moreover, the peak heat release rate and total heat release of MPZSN-MoS2/PAN fiber were remarkably decreased by 49.9% and 38.1% in contrast to pure PAN fiber, indicating its superior fire performance. The gaseous and condensed analysis demonstrated that the addition of MPZSN-MoS2 hybrids inhibited the effusion of pyrolysis products, such as HCN, CO, aliphatic CH compounds, CC compounds and carbonyl compounds, and promoted the generation of graphitized protective char layer on the fiber surface. This work presents a facile strategy for the design of MoS2-based hybrids with multi-components, expanding their potential applications in polymer composites.