New process creates precisely ordered polymer zigzags

By Meghan Rosen

Web edition: August 10, 2012

Wrinkles aren’t just for raisins and soggy fingertips.

A team of MIT scientists has figured out how to create perfectly ordered furrows and folds that could be used for stretchable electronics, sticky surfaces or antireflective coatings. The new wrinkling method uses a special stretching technique to form microscopic zigzags, researchers report in an upcoming Advanced Materials.

“There are dozens of possibilities,” for the miniature wrinkles, says mechanical engineer and study coauthor Mary Boyce. Her team wants to use the herringbone designs to make antifouling coatings — films that can be used to block bacterial buildup on medical devices like catheters and stents.

To create the tiny patterns, researchers vaporized a polymer-forming chemical. Then they let the mist settle on a tightly stretched silicone-based sheet. Letting the taut sheet snap back into shape made the overlying polymer film buckle haphazardly, like a concrete sidewalk after an earthquake. But releasing the sheet’s tension first in one direction, then the other, created precise patterns of V-shaped ribs.

As researchers increased the size of the sheet, the wrinkled structures became more and more uniform — so scaling up should go smoothly. “We were really delighted to see that,” Boyce says.