DEPOSITION OF DOUBLE-LAYER COATINGS FOR PREPARING COMPOSITE MEMBRANES WITH SUPERHYDROPHOBIC PROPERTIES

Abstract

The present paper describes the possibility of formation of a double-layer superhydrophobic coating on a porous substrate from an active gas phase formed via electron-beam dispersion of polymers. A poly(ethylene terephthalate) track-etched membrane with a pore diameter of 250 nm was used as a porous substrate. An ultra-high molecular weight polyethylene was used for deposition as a target material to form the first hydrophobic layer on the membrane surface, and polytetrafluoroethylene was used for deposition as a target to form the second superhydrophobic layer. It is shown that the electron-beam deposition of the ultra-high molecular weight polyethylene layer leads to substantial hydrophobization of the membrane surface. The water contact angle of this layer changes from 92° to 125°, depending on its thickness. This change is due to the development of roughness of the deposited layer having hydrophobic properties with increase in its thickness. It is found that the electron-beam deposition of the polytetrafluoroethylene as a second thin layer results in formation of coating having superhydrophobic properties with water contact angle of 150°–160°. A significant increase in the contact angle is due to the lower free surface energy and more considerable development of the roughness of the fluoropolymer compared with the ultra-high molecular weight polyethylene coating.