Bio-based sodium alginate/polyvinyl alcohol double-network aerogels reinforced by phytic acid and MXene for flame-retardant thermal insulation

Bio-based aerogels are attractive for building thermal protection and fire safety, yet sodium alginate (SA) aerogels are mechanically fragile due to loosely connected, hydrogen-bond-dominated networks, while PVA aerogels often suffer from moisture-sensitive structural stability. Here, we develop a high-performance SPMP composite aerogel by coupling an SA/PVA double-network with phytic-acid (PA)-mediated multipoint interactions and MXene-enabled reinforcement. PA densifies the polymer network via extensive hydrogen bonding and further bridges the matrix to MXene through interaction with Ti-containing sites; freeze–thaw-induced PVA crystallites and MXene nanosheets jointly improve load-bearing capability and thermal shielding. The optimized SPMP aerogel achieves a specific modulus of ~64.4 MPa·cm 3 /g chemical coordinationg −1 , a low thermal conductivity of 0.026 W·m −1 ·K −1 , and robust flame retardancy (LOI 33.9%, UL-94 V-0). After hydrophobic surface modification, it exhibits a water contact angle of 132°, enabling durable water repellency and self-cleaning. This study demonstrates that integrating PA-based co-crosslinking, 2D nanosheet reinforcement, and surface hydrophobic regulation can concurrently upgrade mechanical strength, thermal insulation, and fire resistance in double-network bio-aerogels, offering a sustainable route to next-generation building insulation and protective materials. Download: Download high-res image (131KB) Download: Download full-size image