Construction of Bimetallic ZIF-Derived Co-Ni LDHs on the Surfaces of GO or CNTs with a Recyclable Method: Toward Reduced Toxicity of Gaseous Thermal Decomposition Products of Unsaturated Polyester Resin

This work proposed an idea of recycling in preparing Co-Ni layered double hydroxide (LDH)-derived flame retardants. A novel and feasible method was developed to synthesize CO-Ni LDH-decorated graphene oxide (GO) and carbon nanotubes (CNTs), by sacrificing bimetal zeolitic imidazolate frameworks (ZIFs). Organic ligands that departed from ZIFs were recyclable and can be reused to synthesize ZIFs. ZIFs, as transitional objects, in situ synthesized on the surfaces of GO or CNTs directly suppressed the re-stacking of the carbides and facilitated the preparation of GO@LDHs and CNTs@LDHs. As-prepared hybrids catalytically reduced toxic CO yield during the thermal decomposition of unsaturated polyester resin (UPR). What is more, the release behaviors of aromatic compounds were also suppressed during the pyrolysis process of UPR composites. The addition of GO@LDHs and CNTs@LDHs obviously inhibited the heat release and smoke emission behaviors of the UPR matrix during combustion. Mechanical properties of the UPR matrix also improved by inclusion of the carbides derivatives. This work paved a feasible method to prepare well-dispersed carbides@Co-Ni LDH nanocomposites with a more environmentally friendly method.