Preparation of hydrophobic and oleophobic fine sodium bicarbonate by gel-sol-gel method and enhanced fire extinguishing performance

Functionalized sodium bicarbonate (FSB) powder with hydrophobicity and oleophobicity may provide a new solution to the increasingly severe aircraft engine fires. A one-step way to prepare hydrophobic and oleophobic powders by gel-sol-gel method was developed. Perfluoro copolymer gels were synthesized with PFEA (2-(perfluorooctyl) ethyl acrylate), MMA (methyl methacrylate) and HEMA (N-(2-Hydroxyethyl) acrylamide). The sol-forming properties of five different ratios of PFEA and MMA were investigated. As the proportion of PFEA increased, the oleophobic performance increased but the solubility of the copolymer gel in acetone decreased. The water and oil contact angles would reach the maximum values when PFEA content was the highest. When the mass ratio of PFEA to MMA exceeded 50%, functionalized sodium bicarbonate powder showed a good floating performance on water and aviation kerosene surface. In fire experiments, pure sodium bicarbonate powder was hard to extinguish aviation kerosene pool fires while FSB powder could extinguish the flame easily. The formed FSB powder layer effectively inhibited the flame from spreading on the oil surface. [Display omitted] •A new idea was proposed using gel-sol-gel method to modify powders.•Micron SB powder with hydrophobicity and oleophobicity was successfully prepared.•Water/oil contact angles of FSB powders can reach up to 129.7° and 122.2°.•Floating performances were well while the mass ratios of PFEA to MMA exceeded 50%.•Functionalized SB powder could effectively inhibit pool fires spreading.