Bio-based Supramolecular Intumescent Coatings for Wood Fire Protection

Wood is a ubiquitous construction material, however, its inherent flammability requires the development of effective and environmentally friendly fire-protection strategies. Herein, we present a transparent, self-healing, and bio-based supramolecular intumescent coating for wood protection. The coating was synthesized via a solvent-free multi-step process, integrating a gelatin–phytic acid precursor with a boron–nitrogen coordination complex through controlled melamine reaction. Such coating exhibits good interfacial adhesion to wood, as evidenced by a shear strength of 5.84 MPa. Moreover, it also demonstrated excellent moisture-triggered self-healing ability, which improved scratch resistance and reduced moisture uptake. The coated wood shows significantly improved thermal stability and fire resistance, including a reduction in peak heat release rate (∼57%) and total heat release (∼42%), along with an increased limiting oxygen index (35.5%) and a UL-94 V-0 rating. Based on burnt surface analysis and chemical characterization, the flame-retardant mechanism is elucidated, highlighting synergistic effects in both gas and condensed phases. This work provides a sustainable and effective strategy for wood fire protection and underscores the potential of bio-derived supramolecular architectures in addressing critical safety challenges for bio-based construction materials.