Interface-charring catalysis enables fire-safe and mechanically reinforced epoxy via facile interfacial aggregation induction

Abstract

Aiming to highly efficiently improve the fire safety and mechanical property of intumescent epoxy resin (EP), the interfacial aggregate of mesoporous MCM-41 nanospheres toward ammonia polyphosphate (APP) microparticles was effectively executed. Various characterizations identified the quasi-sphere-on-sphere microstructure of APP@MCM-41 with sustained thermal stability. The addition of APP@MCM-41 into EP matrix gave rise to a featured dispersion with MCM-41 preferentially located at EP/APP interface. The fire evaluation revealed that compared with pristine APP (UL-94 V-1), 9wt% APP@MCM-41 imparted EP matrix with UL-94 V-0 rating. The interfacial aggregate at the interface of EP/APP (7wt%) drove the reduction of peak heat release rate (pHRR) and total smoke production (TSP) by 30.6% and 22.2% respectively. The mechanism investigation via contrastive experiments verified that the interfacial location of MCM-41 remarkably optimized the intumescent cellular structure through the promoted catalytic charring reaction. The proposed adsorptive accumulation of EP volatiles towards EP/APP interface by mesoporous MCM-41 favored a stronger charring reaction. In addition, EP/APP@MCM-41 presented an improved mechanical performance relative to its counterparts due to an enhanced matrix-filler adhesion. In perspective, the proof of concept via interfacial assembly-induced catalytic charring associated with micro/nano hierarchy of conventional fire retardants draw a roadmap towards fire-safe polymers.