Web Date: July 23, 2013
Nanostructures That Heal Themselves
The iridescence of a butterfly’s wing and the stickiness of a gecko’s foot derive their properties from nanoscale structures on their surfaces. Unlike with those natural materials, nanostructures engineered from synthetic materials often lack the ability to heal themselves when damaged. Now a Singaporean team has imprinted nanopatterns into a shape-memory polymer and found that the patterns can repeatedly recover from damage (Langmuir 2013, DOI: 10.1021/la401621j).
Hong Yee Low, a polymer chemist at the Singapore University of Technology & Design, and her team molded a nanopattern into Nafion, a well-studied fluoropolymer-copolymer. They heated Nafion film at 310 °C for 10 minutes and used a mold to imprint rows of pillars, ranging from 500 nm to 5 μm wide, onto the material. After cooling the polymer to room temperature, the researchers bent the pillars by smudging them with a finger, blasting them with a focused electron beam, or squishing them with a diamond stylus. When the team heated the material to 140 °C, past Nafion’s glass transition temperature, the ruined structures regained their original shape. The structures withstood this damage-and-repair process 25 times.
Towards a possible application, Low is now working to mimic the complex nanopatterns on gecko feet with a polyurethane-based polymer that can heal itself. The materials could lead to a new type of dry adhesive.
- Chemical & Engineering News
- ISSN 0009-2347
- Copyright © American Chemical Society