Super Flexible and Ultra‐Lightweight Biomass‐Derived Aerogel With Intrinsic Thermal Insulation Properties: Good Alternative for Non‐Degradable Sponges

Biomass aerogels have attracted tremendous attention worldwide as they are environment‐friendly replacements for organic aerogels. Also, their starting material is biodegradable, non‐toxic, and abundantly available, making them a suitable candidate for different applications. Despite having these advantages, poor mechanical strength and vulnerability to combustion limit their applicability. The present study highlights the fabrication of super flexible and ultralightweight aerogel from chitosan (CS), ammonium polyphosphate (APP), and sodium alginate (SA). The phosphorous functionalization improves thermal insulation compared to CS/SA aerogel. The as‐prepared CS/SA/APP aerogel is super flexible as it can tolerate weight 10 times more than its weight, while on releasing the weight, it retains its original shape and size without any morphological devastation. The thermal insulation property of the aerogel has been proven by the combustion test in which it sustains up to 480 s in continuous Bunsen burner flame. The present work aims to deliver awareness toward the fabrication of biomass‐derived CS/SA/APP aerogel with intrinsic flame retardancy.