Facile fabrication of superhydrophobic coatings with polyimide particles using a reactive electrospraying process

A facile method for polyimide (PI) coating with enhanced hydrophobicity through the deposition of morphology controlled PI particles is presented. An electrospraying process combined with in situ imidization was employed in the fabrication of the PI particles for controllable morphologies as well as hydrophobic multilayered films. We confirmed that in situ imidization accompanying evaporation of the solvent affected the surface morphology of the PI particles during the reactive electrospraying process. The competition of in situ imidization and solvent evaporation in the heating process induces not only the formation of a dimple structure but also the formation of a hollow structure, which was affected by the droplet size. The multilayered film produced by deposition of the PI particles had a microstructured surface with spherical protrusion, micro-dimples, and micro-channels. The multilayered film of PI particles exhibited a hydrophobic surface with water contact angle of 151° due to the microstructured surface of PI coating which was simply but effectively generated by reactive electrospray technique.