Innovative hierarchical fiber membranes bioinspired by penguin feathers for exceptional thermal insulation

Inspired by the extraordinary hierarchical architecture of penguins’ feathers, we have successfully prepared the biomimetic hierarchical fiber membranes. This was achieved by depositing rutile TiO₂ featuring nanocone structures on both the upper and lower surfaces of porous/membrane-pore-like fiber membranes using the chemical bath deposition method. When contrasted with conventional insulating materials (pure wool felt, twill cotton fabric, aramid 1313, polyethylene foam cotton and asbestos cloth), the novel hierarchical fiber membranes display outstanding thermal insulation capabilities (thermal conductivity = 0.0189 W m⁻¹ K⁻¹), remarkable high temperature resistance (more than 50 % of material remaining at 700 °C), excellent flame retardancy, and hydrophobicity (water contact angle exceeding 140°). These exceptional characteristics suggest that the hierarchically structured fiber membranes hold great promise for underwater thermal insulation applications, heralding the entry of the development of advanced thermal insulation materials into a new stage.