Biomass Chitosan-Based Composites for Flame Retardancy and Fire Alarm: Advances and Perspectives

The appeal of chitosan (CS) stems not only from its exceptional char-forming capacity and molecular tailorability as a flame retardant, but also from its intrinsic thermal responsiveness as a potential fire warning, making it a building block of advanced materials for fire management. Herein, this review provides an up-to-date exploration of advancements in CS and its derivative-based multi-functional composites, with a particular focus on the flame-resistant and fire-warning applications. Specifically, these summaries involve various manufactory approaches, the customed flame-retardant regulation (reflected in a higher Limiting Oxygen Index (LOI) value, a V-0 rating, and a decreased peak of heat release rate (pHRR)), a corresponding principle of flame retardancy, different fire-warning modulations (lower warning temperatures and shorter response times), an underlying fire-warning mechanism (electrical current change), and challenges and opportunities for further development (the assistance of artificial intelligence (AI), multi-functional integration). We mainly aim to present a comprehensive overview that can offer strong guidance for the construction of a new generation of advanced CS-based materials.