Leach-resistant modified bamboo with fire-retardant and anti-mildew properties via in situ synthesis

To ensure the long-term fire-retardant (FR) and anti-mildew (AM) of bamboo materials when employed in outdoor settings susceptible to rainfall exposure, high durability is essential. In this study, we achieved water-leaching resistance of FR and AM bamboo through the in situ synthesis of phosphotungstic acid (PW) and silver nitrate (AG) via vacuum-pressure impregnation. The successful synthesis of the nanospheres within the bamboo (referred to as PWAG-B) was confirmed by TEM, FTIR, and XPS. These nanospheres remained intact within the bamboo cell wall after being subjected to a leaching test , with only a negligible mass loss of 0.88   % and virtually no traces of Ag and W in the leachate for PWAG-B 1 . Furthermore, the treated bamboo exhibited superior AM properties, with complete resistance against two types of mildew , namely Botryodiplodia theobromae and Alternaria alternate , as well as stain fungi including Aspergillus niger and Penicillum citrinum . Notably, the treated bamboo displayed reduced thermal and smoke parameters in comparison to untreated bamboo, along with a delayed ignition time . This long-term AM and FR bamboo has the potential for the development of eco-friendly outdoor building materials .