Researchers Develop Superhydrophobic Coating

A multi university team of researchers led by the Harvard John A. Paulson School of Engineering and Applied Sciences has developed a superhydrophobic surface that can last months underwater. This surface has a stable plastron and has plans for a long-lasting surface that can prevent corrosion, prevent the growth of bacteria and marine organisms such as mussels and barnacles, as well as repel blood. 
 
For 20 years researchers have theoretically known that underwater plastron was possible but have been unable to show it experimentally. Plastrons need rough surfaces to form, but roughness makes the surface mechanically unstable and susceptible to small perturbations in temperature, pressure, or tiny defect. The team was inspired by a species of an underwater spider known was the argyroneta aquatica that has millions of rough, water repellent hairs that trap air around its body. 
 
“Research in bioinspired materials is an extremely exciting area that continues to bring into the realm of man-made materials elegant solutions evolved in nature, which allow us to introduce new materials with properties never seen before. This research exemplifies how uncovering these principles can lead to developing surfaces that maintain superhydrophobicity under water,” said professor and the paper’s co-author Joanna Aizenberg.
 
This new surface uses a simple manufacturing technique the team called aerophilic surface, derived from inexpensive titanium alloy with a long sating plastron which keeps the surface dry for thousands of hours. 
 
“We used a characterization method that has been suggested by theorists 20 years ago to prove that our surface is stable, which means that not only have we made a novel type of extremely repellent, extremely durable superhydrophobic surface, but we can also have a pathway of doing it again with a different material,” said Tesler, lead author of the paper.
 
To prove the stability of the plastron, researchers heavily tested the surface by bending, twisting, and blasting it with cold and hot water, as well as abrading it with sand and steel to block the surface remaining aerophilic. It withstood 208 days of submersion in water and hundreds of dunks in a petri dish of blood. It reduced E. coli growth and growth of barnacles and completely stopped the adhesion of mussels. 
 
This surface has potential for underwater applications as well as biomedical applications where it could be used as a biodegradable implant such as stents or to reduce infection after surgery.