A simple strategy for preparing Cu2+-doped flame retardants to enhance the fire resistance of wood

The ethnic minority villages in Qiandongnan, Guizhou, are renowned for a large number of traditional stilted wooden buildings, which hold significant ethnic characteristics and cultural value. However, the widespread use of Chinese fir ( Cunninghamia lanceolata ) as construction material poses significant fire safety challenges due to its inherent combustibility, highlighting the need for effective flame-retardant treatments for this species of timber. This study proposed a green and facile flame-retardant strategy based on a supramolecular chelated flame retardant (Cu-AP), assembled from aminotris (methylenephosphonic acid) (ATMP), piperazine (PI), and Cu 2+ . Modified wood was prepared via a vacuum impregnation process. This method significantly enhanced flame retardancy at low concentrations and short treatment times. The introduction of Cu 2+ promoted rapid char formation and aromatization, improving thermal stability and smoke suppression. The treated wood achieved a UL-94 V-0 rating, an increased limiting oxygen index (LOI) of 29.6%, and a peak heat release rate reduction of over 65% in cone calorimetry. This work presented a practical modification approach and material solution for fire protection of traditional stilted wooden buildings with regional characteristics.