Facile fabrication of multifunctional transparent fire-retardant coatings with excellent fire resistance, antibacterial and anti-aging properties

A series of organophosphate-grafted nano-TiO2 was synthesized and then applied in amino resin to obtain multifunctional transparent fire-retardant coatings with superior fire resistance, antibacterial and anti-aging properties. Transparency analysis reveals that the addition of nano-TiO2 slightly decreases the light transmittance of the resulting MTiPPBs coatings, which is still remained a high level of transparency. The results of fire tests show that the presence of nano-TiO2 exhibits well synergistic effect on strengthening the smoke suppression property and fire resistance of the MTiPPBs coatings, which is ascribed to the formation of more P-containing cross-linked and aromatic structures in the condensed phase that improve the barrier effect of intumescent char against fire, as supported by scanning electron microscope (SEM) and energy dispersion spectrum (EDS) analyses. When the weight ratio of PPB and nano-TiO2 is 99.7:0.3, the obtained MTiPPB3 coating shows a 69.5% decrement in smoke density rating and an 83.3% decrement in flame spread rating in comparison to MTiPPB0 coating without nano-TiO2. The accelerated aging test reveals that the presence of nano-TiO2 can minimize the blistering, powdering, and cracking phenomena of the multifunctional coatings, thus displaying durable fire-resistant and smoke suppression effects. Meanwhile, the addition of nano-TiO2 greatly enhances the antibacterial activity of the multifunctional coatings, and MTiPPB3 coating obtains a 45.6% improvement in antibacterial activity index against Escherichia coli compared to MTiPPB0 coating without nano-TiO2.