Phosphorus/Nitrogen-Codoped Molybdenum Disulfide/Cobalt Borate Nanostructures for Flame-Retardant and Tribological Applications
Bin Zou, Shuilai Qiu, Ziyan Qian, Jingwen Wang, Yifan Zhou, Zhoumei Xu, Wenhao Yang, Weiyi Xing
Abstract
Polymers used in almost any situation face the threat of sudden fire, and application scenarios with high requirements on friction performances of polymers are no exception. Herein, P- and N-codoped molybdenum disulfide (PNMoS2) nanosheets were fabricated via the original process of ball milling, followed by annealing, which subsequently served as the template to grow the two-dimensional (2D) cobalt borate (Co–Bi) ultrathin nanosheets for the generation of PNMoS2@Co–Bi dual sheets. With the introduction of 2 wt % PNMoS2@Co–Bi dual nanosheets into epoxy resin (EP), defined as EP/PNMoS2@Co-Bi, an obvious reduced peak heat release rate of 28.0% and a total heat release of 27.9%, respectively, were obtained. It is noted that the total smoke release, which is vital for evacuation and life safety, has been reduced by 41.8%. In addition, EP/PNMoS2@Co–Bi achieved a significantly improved LOI, UL-94, and thermal performance, along with the high char yield (22.9 wt %) and remarkably decreased mass loss rate. Interestingly, the loading of 2 wt % PNMoS2 has the lowest friction coefficient value (decrease by 18.7%) and volume wear rate (46.1% reduction than pure EP), which is attributed to the PNMoS2 nanosheets that can generate the uniform lubricating transfer layer. The outstanding properties of EP nanocomposites are attributed to the coupled effects between PNMoS2 and Co–Bi ultrathin sheets with an enhanced interface interaction in the EP matrix. This study manifests the extensive application of well-designed PNMoS2@Co–Bi nanohybrids in the fire safety and wear resistance of polymers.