Superhydrophobic nanocellulose aerogel for thermal insulation and thermal resistance up to 1300 °C

Nanoellulose aerogel (NCA) has the advantages of good flexibility, low density, and excellent thermal insulation. Its raw materials are widely sourced, renewable, and degraded, thus NCA has attracted significant interest of researchers in the field of insulation. However, low strength, hydrophilicity, and flammability seriously hinder its application. Here, a superhydrophobic NCA (Si-PA-PAE-NCA) with a multiscale structure is reported. Si-PAPAE-NCA exhibits excellent compression strain (up to 8.674 MPa with strain at 80 %). A low thermal conductivity of 23.9 mW m(- 1) K- 1 endows this aerogel with superior thermal insulation property. Compared to only the surface superhydrophobility of other NCAs, both the surface and interior water contact angles of Si-PA-PAE-NCA are up to 157 degrees. Owing to this distinguished superhydrophobicity, Si-PA-PAE-NCA can maintain its stable thermal insulation property in a high humidity environment (90 % humidity). Importantly, Si-PA-PAE-NCA can withstand 1300 degree celsius flame for 70 min, far exceeding previously reported NCAs. Besides, this aerogel exhibits the highest LOI value (45.9 %) ever recorded for NCAs thus far. Notably, there is no inorganic substance within the aerogel. Together with its scalability, sustainability, and degradability, Si-PA-PAE-NCA will have great application prospects in the insulation area.