Recyclable and self-healing aerogel: A high-performance polyvinyl alcohol material based on DOPO grafting and phosphonitrile - Schiff base dynamic network

Polyvinyl alcohol (PVA) aerogels with excellent environmental performance have been recognized as ideal materials to replace non-biodegradable polymer foams. However, due to their high flammability, their application scope is severely limited. Therefore, research addressing these shortcomings is essential. In this study, Schiff base structures were synthesized based on phosphazene rings rich in P and N elements and grafted with the highly effective flame retardant DOPO (9,10-Dihydro-9-oxa-10-phosphaphenanthrene 10-oxide). The resulting product, denoted as HPDO, was incorporated into an aerogel system as a flame retardant. Notably, compared to pure PVA aerogel, the PVA composite aerogel with 10 parts HPDO flame retardant per hundred of PVA aerogel (PVA/HPDO 10) showed a 68.68% reduction in the peak heat release rate (PHRR) Furthermore, the PVA/HPDO composite aerogels had excellent resilience and fatigue resistance, retaining 82.48% of the original stress after 50 compression cycles at 80% compressive strain. What's more, composite aerogels also exhibit outstanding self-healing and recyclability, which offer new solutions for extending the service life of aerogels. Therefore, PVA/HPDO aerogels had great potential for practical applications due to their self-healing, recyclable, flame-retardant, excellent resilience, and fatigue resistance properties.