Organic crystals use shape-memory to improve plastic electronics

Shape-shifting structural materials are made with metal alloys, but the new generation of economical printable plastic electronics is poised also to benefit from this phenomenon.

The findings from the international team of researchers are published in Nature Communications and confirm the shape-memory phenomenon in two organic semiconductors materials.

Devices such as expandable stents that open and unblock clogged human blood vessels use shape-memory technology. Heat, light and electrical signals, or mechanic forces pass information through the devices, prompting them to expand, contract, bend and morph back into their original form. This effect works well with metals, but remains problematic in synthetic organic materials because of the complexity of the molecules used to create them.

"The shape-memory phenomenon is common in nature, but we are not really sure about nature's design rules at the molecular level," said professor of chemical and biomolecular engineering and co-author of the study, Ying Diao from the University of Illinoi at Urbana-Champaign. "Nature uses organic compounds that are very different from the metal alloys used in shape-memory materials on the market today. In naturally occurring shape-memory materials, the molecules transform cooperatively, meaning that they all move together during shape change. Otherwise, these materials would shatter and the shape change would not be reversible and ultrafast."