Bioderived Bilayer Shell Modification beta-FeOOH Nanorods via Self-Assembly Technique as Sustainable Flame Retardants for Enhancing Flame Retardancy of Epoxy Resin (vol 306, 2100239, 2021)

The design and application of bioderived flame retardants have been widely conducted to meet the concept of green and sustainable development. Here, self-assembly technique is used to prepare core-shell bioderived additives by using beta-FeOOH as the core and polydopamine (PDA)/tannic acid (TA) bilayer as the shell, following adsorption of nickel ions to enhance the thermal stability, flame retardancy, and mechanical properties of epoxy resin (EP). The molecular structure of biobased resources is rich in hydroxyl groups and carbon content, which can be dehydrated and carbonized during combustion and promote the formation of robust protective char layer. With the addition of 5 wt% beta-FeOOH@PTNi, the EP composites can pass V-0 rating in the UL-94 test. The peak heat release rate and total heat release decrease by 28.4% and 17.4% compared with pure EP. The bioderived nanorods can capture the oxygen free radicals, contributing to flame retarding in gaseous phase. Thus, the release of high-toxic CO and flammable gaseous is significantly suppressed. Besides, the storage modulus of EP composites increases by 16.0% with the addition of 5% beta-FeOOH@PTNi compared with pure EP. This work provides a sustainable methodology for the design of bioderived flame retardants for EP.