Oligosilazane cured by moisture as fluorine-free hydrophobic coating for waterproof polymer-matrix composite materials

Preceramic oligosilazane was applied as a waterproof hydrophobic surface coating for electromagnetic wave-transmitting material (silica cloth-reinforced bismaleimide laminated composite). Oligosilazane spread readily on the surface of the material, due to its good wetting ability, enabling formation of silazane coatings using various processing methods such as spraying, dipping, wiping, etc. When using oligosilazane containing micrometer-sized silica particles as filler, ahydrophobic surface was realized after moisture curing under ambient condition. The hydrophobic surface with oligosilazane coating inhibited water absorption shows promise for application as a waterproof surface coating of electromagnetic wave-transmitting materials.