A facile and small-molecule regulated borate network gelation to improve the mildew proof, fire-retardant of bamboo

Bamboo lacks transverse tissues, which negatively affect the intercellular water/nutrient molecules transfer and predisposed to mold. Borate is widely used industrially for wood protection but it still short-time achieved. Here, small molecules of natural polyphenol-tannic acid (TA) were applied to tune the bonding types on bamboo inner surfaces and in situ construct gel-like networks with boric acid (BA) in the xylem. The borate was affinity towards catechol groups to facilely fabricate borate-catechol covalent linkages. Meantime, the all small molecules' gel network allows the boron remains a small amount of dynamic mobility and thus to increase bamboo durability. Take advantage of these small molecules gelling, the treated bamboo strips maintained good bending strength (118.5 MPa) comparable to the unmodified one, flame-retardant, and excellent mildew proof effect for the Aspergillus Niger, special long-time anti-mold feature at quite high moisture condition (97 % relative humidity) for 60-day. Overall, this borate modified bamboo shows great promising to drive the large-scale production of anti-mold bamboo. • In situ synthesis of TA-BA gel-like network was used to control bamboo mildew. • Tuned the bamboo cell walls interfacial bonding types to regulate the internal moisture of bamboo. • The mildew resistance of bamboo is more than 60 days.