Engineering news
Researchers have developed a multifunctional smart material that can change shape when activated by heat or light and assemble and disassemble itself.
Smart materials that can react to external stimuli, like light or heat, have a variety of potential applications, such as for actuators, drug delivery systems and self-assembling devices. For instance, smart materials could change shape to unfold a solar panel on a space satellite without need of a battery-powered mechanical device.
The team at Washington State University (WSU), led by Michael Kessler, professor in the WSU School of Mechanical and Materials Engineering (MME), said this is the first time researchers have been able to combine several smart abilities, including shape memory behaviour, light-activated movement and self-healing behaviour, into one material. They have published their work in ACS Applied Materials & Interfaces.
Up until now smart materials haven't come into widespread use because they are difficult to make and often can only perform one function at a time. Researchers also have struggled to reprocess the material so its special properties can continually repeat themselves.
The team worked with a class of long-chain molecules, called liquid crystalline networks (LCNs), which provide order in one direction and give material unique properties. The researchers took advantage of the way the material changes in response to heat to induce a unique three-way shape shifting behaviour. They added groups of atoms that react to polarized light and used dynamic chemical bonds to improve the material's reprocessing abilities.
"We knew these different technologies worked independently and tried to combine them in a way that would be compatible,'' said Kessler.
The resulting material reacts to light, can remember its shape as it folds and unfolds and can heal itself when damaged. For instance, a razor blade scratch in the material can be fixed by applying ultraviolet light. The material's movements can be pre-programmed and its properties tailored.
The research was carried out in collaboration with Orlando Rio, a researcher at Oak Ridge National Laboratory. Researchers at Oak Ridge used facilities at their Centre for Nanophase Materials Sciences to study the mechanisms responsible for the material's unique abilities.
The research is in keeping with WSU's ‘Grand Challenges’, a suite of research initiatives aimed at large societal issues.