Ohio State University (OSU) researchers have used a nano-engineered texture to coat plastic-based synthetic leather, making oil and water roll off and preventing stickiness in temperatures up to 70 degrees Celsius (158 degrees Fahrenheit). The coating, based on the bumpy, water-repellent surface of lotus leaves, has been previously used at OSU to devise self-cleaning glass and a mesh to separate oil from water.

The market for synthetic leather has grown because it’s cheaper and easier to work with than genuine leather. Synthetic leather is made from fabric coated with plastic — usually polyurethane (PU) or polyvinyl chloride (PVC). Both of those materials can be molded into flat sheets with grooves to impart a leather-like texture. It gets sticky at high temperatures, however, because heat softens the plastic surface.

In their work, the researchers at first tried to create a bumpy texture by spraying a coating of silica nanoparticles onto the synthetic leather surface; its plastic nature, however, prevented the nanoparticles from sticking. After cleaning with an ultraviolet light method commonly used in computer chip manufacturing, the team was able to get the nanoparticles to stick. They sealed them with a silicone resin, resulting in a mostly-transparent coating through which the leather-like texture would still be visible.

The coating also imparts wear resistance and a self-cleaning property. To test the latter, the researchers sprayed black silicon carbide powder onto the coated material and measured how much of the powder could be washed away by a single water droplet. On untreated synthetic leather, it was about 10 percent. On leather treated with their coating, it was 90 percent.

Potential applications are many, according to OSU mechanical engineering professor Bharat Bhushan: furniture, automotive interiors, clothing, shoes, handbags — basically anything for which synthetic leather can be used.

The research appears in the journal Colloids and Surfaces A.