Bionic octopus tentacle structure-inspired engineering of HPP@PBA nanotubes: Towards mechanically reinforced epoxy nanocomposites with outstanding flame retardancy and smoke suppression

Developing high-performance epoxy (EP) nanocomposites that balance flame retardancy and mechanical properties has been a significant challenge. In this work, a novel hierarchical hybrid flame retardant HPP@PBA with a bionic octopus tentacle structure was successfully constructed. The organic coating composed of phytic acid (PA) and polyaniline (PANI), and CoFe-Prussian blue analogue nanoparticles (CoFe-PBA), effectively enhances the interfacial interaction between halloysite nanotubes (HNTs) and the EP matrix, promoting the formation of a mechanical interlocking structure. By introducing 5 wt% HPP@PBA, the tensile strength and impact strength of the composites increase by 62.4 % and 38.7 %, respectively. EP/HPP@PBA also exhibits excellent flame retardancy and smoke suppression properties. The limiting oxygen index (LOI) of the EP composites reached 33.0 %, achieving the UL-94 V0 rating. Cone calorimetry test (CCT) shows that, compared with pure EP, the peak of heat release rate (pHRR), total heat release (THR), peak of smoke production rate (pSPR), total smoke production (TSP), and peak of carbon monoxide production (COP) of EP/HPP@PBA are reduced by 40.7 %, 34.0 %, 47.2 %, 42.5 %, and 36.6 %, respectively. Additionally, the flame retardant and mechanical enhancement mechanisms of hybrids in EP composites are systematically investigated. This work provides a feasible approach for preparing multifunctional high-performance EP nanocomposites.