Preparation of high‐hydrophobic polyvinyl alcohol‐based composite aerogel fibers containing organosilicon for effective thermal insulation

Abstract Polyvinyl alcohol (PVA) aerogel fibers exhibit encouraging potential as thermal insulation materials, but their hydrophilicity easily results in severe collapse of the aerogel pore structure. Therefore, hydrophobic modification of PVA aerogel fibers is of significance to their structural stability and durability. Here, a novel process was proposed to continuously generate high‐hydrophobic PVA‐based composite aerogel fibers containing polymethylsilsesquioxane (PMSQ) by introducing methyltrimethoxysilane (MTMS) through freeze‐thawing, freeze‐spinning, and freeze‐drying processes. With optimized freezing time and MTMS content, the PVA‐based composite solution showed good spinnability, and the resulting PVA/PMSQ (PVASi) aerogel fibers were endowed with markedly enhanced hydrophobicity and excellent weavability due to sufficient mechanical properties. Most importantly, the aerogel fibers possessed excellent hydrophobic structural stability after 12 h or 50‐cycle soaking and 50‐cycle washing. Benefiting from these superior characteristics, the aerogel fibers were demonstrated to be effective thermal insulators in high humidity (>90% relative humidity) and after washing for 50 cycles.