High-Strength, Flexible, Hydrophobic, Sound-Absorbing, and Flame-Retardant Poly(vinyl alcohol)/Polyelectrolyte Complex Aerogels

Abstract

Biodegradable aerogels with flexibility and high strength are attractive for construction, and acoustic and thermal insulation but are seriously plagued by their flammability. Improving the flame retardancy of these aerogels has been a hot topic of research and inorganic fillers, and layered materials have been widely used for this purpose. However, the poor interfacial compatibility of these fillers has affected the processability and mechanical properties of the aerogels and reduced their overall performance. In this study, we have used a completely organic and sustainable polyelectrolyte complex (PEC) as a filler for fabricating mechanically strong, sound-absorbing, and flame-retardant poly(vinyl alcohol) (PVA) aerogels with the aid of an environmentally friendly freeze-drying method. The noncovalent interactions between the polymer and filler ensured excellent compatibility as well as interfacial adhesion of the filler, and we could achieve a perfect balance between the density and mechanical properties of the aerogels. The prepared aerogels exhibited flexibility, good sound absorption ability in the mid-frequency range, and excellent flame retardancy (LOI ∼28%) with self-extinguishing behavior. A simple silane modification endowed sticky hydrophobicity to the aerogels and further enhanced their antifire properties. These sustainable multifunctional aerogels could find a plethora of applications in real life, particularly in buildings and structures as fire safety materials and sound insulators.