Scalable host–guest engineering of ambient-pressure-dried chitosan/aramid nanofiber aerogels for mechanically robust and fire-safe thermal insulation

A successive APD-mediated host–guest strategy was developed for CS@ANF aerogels. • ANFs formed an interfacially reinforced structure within the CS skeleton. • CS@ANF0.5 achieved a compressive strength and modulus of 3.5 and 2.7 MPa. • CS@ANF0.5 showed effective thermal protection and enhanced flame retardancy. Biomass-derived aerogels provide sustainable, lightweight porous platforms with tunable structures and broad functional potential. However, their practical use is still limited by energy-intensive drying routes, weak mechanical integrity, and the inherent flame sensitivity of organic porous skeletons. Here, a successive ambient-pressure drying (APD)-mediated host–guest assembly strategy was developed to construct robust chitosan/aramid nanofiber (CS@ANF) composite aerogels. A lightweight CS aerogel was first prepared by APD as the host scaffold, followed by infiltration of guest ANF sol and a second APD step that formed an ANF-enriched reinforcing structure along the pore walls rather than a bulk-blended phase. Experiments and finite-element simulations reveal that the ANF-reinforced pore-wall structure promotes more effective stress transfer and suppresses localized structural collapse. The resulting composite aerogel achieved a compressive strength of 3.5 MPa and a compressive modulus of 2.7 MPa, together with improved tensile performance and cyclic stability. Moreover, the composite aerogel delivers reliable high-temperature protection and enhanced flame retardancy with more intact char residues. This host–guest APD strategy offers a potentially scalable route to mechanically resilient and fire-safe biomass-based aerogels.