Figure 1. Schematic of “flip-flop” vs “non–flip-flop” surface properties.

For the “flip-flop” coating, water is able to penetrate down through the repellent surfactant tails of the functional layer (fluorosurfactant) to the high surface tension portion of the coating while the bulky oil molecules are repelled. For non–flip-flop coatings, water is unable to penetrate the functional layer (fluorosilane).