Ribonucleic acid as an intrinsically synergistic bio-derived flame retardant

Abstract

Ribonucleic acid (RNA) was investigated as an intrinsically synergistic biomolecular flame retardant, exhibiting distinct thermal behavior and an intumescent char-forming ability. Despite the growing interest in bio-derived flame retardants, the flame-retardant potential of RNA has not been previously explored. Owing to its intrinsically high carbon, nitrogen, and phosphorus content, together with the presence of uracil and a 2′-hydroxyl group, RNA undergoes efficient dehydration and promotes effective intumescent char formation during combustion. Compared with the structurally similar deoxyribonucleic acid (DNA), RNA exhibited distinct thermal transitions and superior char yield. When applied as a coating on polyurethane foam (PUF), RNA increases the residual mass from 0.8% to 37.5%, elevates the limiting oxygen index (LOI) to 29.3%, and enables a UL-94 HF-1 classification. Cone calorimetry further shows a 49.4% reduction in peak heat release rate (p-HRR). These findings demonstrate that RNA functions as a sustainable and inherently synergistic bio-derived flame retardant by suggesting combined condensed-phase protection with likely gas-dilution/gas-phase contributions.