Zinc-containing metal-organic frameworks nanospheres for flame retardation and thermal insulation performance in epoxy resin-based coatings

A low-cost metal-organic framework suitable for high-efficiency production is synthesized by a solvothermal method using a transition element Zn and 4-hydroxybenzoic acid (HBA). These hollow Zn-HBA nanospheres are added to epoxy resin-based coating (E 51-LP 3) to form a flame-retardant and thermal insulation coating. Data obtained from cone calorimetric test demonstrates that the addition of Zn-HBA nanospheres effectively inhibits the combustion and smoke release of the coating. At Zn-HBA content of 50.0 vol%, the limiting oxygen index increases by 46% (from 21.5% to 31.5%) and UL 94 rating reaches V-0. Moreover, the thermal insulation performance of E 51-LP 3 containing 50 vol% Zn-HBA as flame-retardant is also significantly improved. This work demonstrates that these low-cost hollow Zn-HBA nanospheres, suitable for high-efficiency production, can be used as an additive to produce nanocoatings with both excellent flame-retardant and thermal insulation properties, while providing a solution for reducing the cost of multifunctional coatings.