Performance improvement of multifunctional sodium alginate aerogels by synergistic effect for energy-efficient buildings

Biomass aerogels have attracted significant research interests in the field of thermal insulation due to their low thermal conductivity, high porosity and biodegradability. However, poor flame retardation and compressive strength limit their wide application. In this study, a high-strength, excellent flame retardant and heat insulating composite aerogel (SAP-Al/PC) was successfully fabricated by incorporating sodium alginate (SA)/polyvinyl alcohol (PVA)-Al (denoted as SAP-Al) with phytic acid/chitosan (PA/CS), and hydrophobic modification of SAP-Al/PC was also performed via chemical vapor deposition of methyltrimethoxysilane (MTMS). The results showed that SAP-Al/PC exhibited outstanding flame retardation with a high limit oxygen index (LOI) of 62.1% and a significant decrease in peak heat release rate (78.6%) and smoke release rate (88.1%) compared to SAP-Al. The SAP-Al/PC also displayed good thermal stability, low thermal conductivity (42.76 mW/(m·K)), high specific modulus (22.89 kN∙m∙kg −1 ) and good water resistance. This study provides a novel strategy for the preparation of multifunctional aerogels, demonstrating their application potential in the fields of thermal insulation and flame retardation.