Tailored Catalysis Inducing Exceptionally Fire-Safe and Mechanically Reinforced Epoxy at An Ultralow Loading.

Abstract

An unconventional P/N/Si-free fire safety of epoxy at an ultralow loading with a significantly improved mechanical robustness and toughness via a mere nanocomposite technique is a great challenge. To achieve the goal, a proof of concept is proposed associated with a hierarchical manipulation of catalysis-tailored FexSy ultrathin nanosheets on organic-layered double hydroxide (LDH-DBS@FexSy) toward the formation of porous piling structure via a self-sacrificing conversion of metal-organic framework. A sufficient characterization certified the targeted architecture and composition. A P/N/Si-free ultralow loading of 2 wt % LDH-DBS@FexSy (i.e., 0.6 wt % FexSy) imparted epoxy with UL-94 V-0 rating, a 36.1% reduction of peak heat release rate, as well as a pronounced fire-protection feature. A systematic contrastive investigation evidenced a time-dependent fire-shielding effect induced by a featured catalysis-tailored ultrafast charring behavior at the interface of epoxy and LDH nanosheets. Intriguingly, the tensile strength, impact strength, and flexural strength were simultaneously enhanced by 62.2, 185.4, and 62.9%, respectively, with a 0.6 wt % incorporation of FexSy hierarchy on the basis of a "root-soil"-inspired interfacial "interlocking" structure. In perspective, an integrated manipulation of an interface catalysis-tailored ultrafast charring and hierarchical "interlocking" construction offer an effective balance of the fire safety, mechanical robustness, and toughness of polymers.