Researchers have developed a multifunctional fire-protective coating that not only shields materials from extreme heat but also provides an early warning of fire and can be recycled into new flame-retardant materials at the end of its life.

The work, published in Polymer Degradation and Stability, demonstrates a promising strategy for combining fire safety, sustainability and circularity within a single material system.

The study focuses on the development of an innovative epoxy-based coating incorporating a bio-based intumescent flame retardant derived from phytic acid, together with graphene oxide (GO).

By carefully engineering the interactions between the flame-retardant component and the polymer matrix, researchers from IMDEA Materials, the Technical University of Madrid (UPM), Pekin University and China Jiliang University, created a coating capable of delivering multiple functionalities while maintaining excellent fire performance.

Fire-protective coatings play a critical role in protecting infrastructure, transportation systems and industrial equipment. However, conventional coatings are typically designed for a single purpose: delaying heat transfer and structural failure during fire events.

The newly developed system takes a broader approach by integrating three key functions within the same coating: fire protection, fire warning and material upcycling and reuse,

This multifunctionality was achieved through the combination of a phytic acid-derived reactive flame retardant, referred to as PAMA, with graphene oxide dispersed within an epoxy resin network. When tested on aluminum substrates exposed directly to a 1200°C flame, the coated samples demonstrated remarkable thermal protection.

After 15 minutes of flame exposure, the temperature on the reverse side of the coated aluminum remained below 400°C. In contrast, an unprotected aluminum plate suffered complete burn-through after approximately two minutes.

The high level of protection results from the coating’s ability to form a robust insulating char layer during combustion. This char acts as a barrier, slowing heat transfer and helping preserve the structural integrity of the underlying material.

Beyond thermal protection, the coating is also capable of acting as an active fire-warning system.

Graphene oxide plays a central role in this functionality. Under flame exposure, the material undergoes a rapid temperature-induced transition in electrical conductivity. This change can be used to trigger an alarm signal in approximately 3.5 seconds, providing valuable early warning before severe damage occurs.

The integration of passive fire protection and active fire detection within a single coating represents an important step toward smarter fire-safe materials for buildings, electronics and industrial applications.

The third aspect of this research is its focus on sustainability.

Rather than treating end-of-life coatings as waste, the researchers demonstrated that the material can be mechanically processed into a recycled coating powder. Importantly, the recovered material retains nitrogen-, phosphorus- and silicon-containing structures that promote char formation and fire resistance.

The recycled powder was subsequently incorporated into polypropylene together with ammonium polyphosphate with the resulting composites exhibiting excellent flame-retardant performance

The research team behind the findings includes Qi Chen, Dr. Wei Tang, Dr. José Sánchez del Río, Dr. Xiaolu Li and Prof. De-Yi Wang.