Fire-resistant and thermal-insulating alginate aerogel with intelligent bionic armor for exceptional mechanical and fire early-warning performance

Biodegradable aerogels are crucial for global sustainable development and dual-carbon economy, but their poor fire safety, strength, and durability under harsh conditions have severely limited their application. In this work, an intelligent “artificial skeleton” was put on the SA aerogel surface through surface crosslink growth and intermolecular hydrogen bonding. This endows the SA aerogel with excellent mechanical and water-resistant properties while maintaining its outstanding thermal insulation performance. Meanwhile, the directionally assembled GO intelligent response layer can provide early warning performance in case of fire or relatively high temperature. This “intelligent armor” protective structure has shown great application prospects in the emerging fields of fire-fighting suits, building walls, and spacecraft housings. [Display omitted] •A bio-based alginate multifunctional aerogel (SA@HAP@GO) with “intelligent bionic armor” was constructed through surface microcalcification, hydroxyapatite growth, and directional assembly.•SA@HAP@GO aerogel has excellent mechanical strength, water resistance, thermal insulation performance (0.03537 W m-1K−1), and fast and lasting fire warning response (∼1.95 s), which can be used as an ideal intelligent fire alarm material.•Exceptional fire shielding performances e.g., the human fingers can be placed on the back of material during a fire and LOI of ∼ 61.5 %. Intelligent bio-based aerogels have attracted increasing attention in several key areas due to their unique porous structure and sustainability, but they suffer from poor fire safety, strength, and durability under harsh conditions. Here, we prepared sodium alginate/hydroxyapatite/graphene oxide (SA@HAP@GO) aerogel by in-situ growth and directional assembly technology, and an intelligent “bionic armor” was put on the surface of SA aerogel. It not only endows aerogel with high strength (2.3 MPa) and long-time water resistance (30 days) but also maintains the lightweight (0.039 g cm−3) and thermal insulation properties (0.03537 W m-1K−1) of original aerogel. Under fire conditions, the compact physical barrier makes aerogel obtain the excellent fire-resistant stability and fire-safety performance. Besides, the directional assembly of GO and the chelating effect of Ca2+ on aerogel surface promote the formation of a three-dimensional electron transport network during reduction process, thus achieving a fast and long-lasting fire early-warning response (1.95 s)