Preparation of multifunctional flame-retardant and superhydrophobic composite wood by iron ions doped phytic acid-based nanosheets

The inherent moisture absorption and flammability of wood can diminish its practical application value. In this research, a phytic acid-based flame retardant (PM) was synthesized by a hydrothermal method. Iron ions-doped phytic acid-based nanosheets (PM-Fe3+) deposited on wood surface by vacuum impregnation. Subsequently, the wood was hydrophobically modified with octadecylamine (OA), resulting in the successful fabrication of superhydrophobic and flame-retardant composite wood (PM-Fe3+/OA/wood). The influence of various coating components on the wettability, heat, and flame retardancy properties of composite wood was examined through water contact angle (WCA), vertical burning tests (UL-94)， limiting oxygen index (LOI), and a cone calorimetry test. The results indicated that the WCA of PM-Fe3+/OA/wood was 154.9°. The composite wood possessed exceptional contamination resistance and self-cleaning properties due to its superhydrophobic surface. Furthermore, due to the dry surface of PM-Fe3+/OA/wood, it exhibited superior resistance to mold in comparison to natural wood. The combustion test results indicated that PM-Fe3+/OA wood exhibited an extremely short time to self-extinguish, achieving V-0 rating. It had a LOI value of 38.6%. Additionally, in the cone calorimetry test, the peak heat release rate (PHRR) and total heat release (THR) of composite wood were reduced by 56.6% and 52.2%, respectively. In summary, this work provides an attractive strategy for obtaining wood with superhydrophobic and flame-retardant properties, which enhances its practical application value.