Self-Cross-Linking Hydrophobic Flame-Retardant Fluorescent Aerogel without External Modifiers

Hydrophobizing hydrophilic aerogels is both necessary and complex, as the introduction of hydrophobic modifiers often compromises key properties, such as density and mechanical performance. In this study, we demonstrate a self-cross-linking hydrophobic flame-retardant fluorescent aerogel without the use of external modifiers. We explore the chemical reaction between a maleic anhydride copolymer and ammonia, leading to a ring-opening reaction that interacts with the carboxyl and hydroxyl groups of ammonium alginate. This process enables hybrid cross-linking between molecular chains without the need for additional cross-linking agents. Furthermore, it facilitates a significant hydrophilic-to-hydrophobic transition throughout the cross-linking process. The resulting aerogels exhibit enhanced mechanical and hydrophobic properties, withstanding up to 80% compressive deformation without visible cracking and showing resilience. The contact angle of the aerogel surface is 131°, indicating effective self-hydrophobicity. This research also explores the structural changes occurring during the cross-linking process and examines how different raw material ratios influence overall performance. In addition, the aerogels demonstrate both flame retardancy and fluorescence, enhancing their versatility. This approach offers a strategy for creating polymer aerogels with high flame retardancy and hydrophobicity without relying on external modifiers.