A reversibly flame-retardant thermal regulation material inspired by leaf transpiration

The demand for advanced fire-retardant wearable materials has increased with a rise in fire disasters in modern society. However, traditional fabrics have some drawbacks including non-temperature regulation, non-recyclability and contaminated products. Here, inspired by leaf transpiration, we prepared a reversibly flame-retardant thermal regulation material (LPWH). Wood cellulose skeleton is expected to be a reinforced mechanical scaffold by imitating the role of leaf vein for water collection and transportation. In parallel, to mimic the mesophyll cells around leaf vein, a hydrophilic and porous phase-change hydrogel aggregation is prepared by anchoring polyethyleneglycoldiacrylate-co-sodium vinylsulfonate copolymer on cellulose fibers and subsequent in-situ assembly of sodium alginate. This precise combination creates an artificial transpiration tissue, achieving effective heat dissipation and temperature regulation via water transpiration and phase-change behavior of hydrogel aggregation. LPWH shows a longer ignited time of 150 s (71% extension), a lower total smoke release of 22.3 m2/m2 (76% reduction), together with an ultralow fire growth index of 2.4 compared to commercial fire-retardant cotton fabric. Moreover, reversible fire retardancy (30 cycles) and great mechanical property (351 times higher than pure phase-change hydrogel) are demonstrated, suggesting LPWH can be the next generation of the pollution-free, recyclable temperature-regulated fireproof suit.