Ultrafast Oleophobic-Hydrophilic Switching Surfaces for Antifogging, Self-Cleaning, and Oil Water Separation

Smooth copolymer-fluorosurfactant complex film surfaces are found to exhibit fast oleophobic-hydrophilic switching behavior. Equilibration of the high oil contact angle (hexadecane = 80 degrees) and low water contact angle (<10 degrees) values occurs within 10 s of droplet impact. These optically transparent surfaces display excellent antifogging and selfcleaning properties. The magnitude of oleophobic-hydrophilic switching can be further enhanced by the incorporation of surface roughness to an extent that it reaches a sufficiently high level (water contact angle <10 degrees and hexadecane contact angle >110 degrees), which, when combined with the inherent ultrafast switching speed, yields oil water mixture separation efficiencies exceeding 98%.