"We knew these different technologies worked independently and tried to combine them in a way that would be compatible."Michael Kessler, Washington State University

Researchers at Washington State University (WSU) have developed a unique, multifunctional smart material that can change shape on exposure to heat or light, as well as assembling and disassembling itself. This is the first time several smart abilities, including shape-memory behavior, light-activated movement and self-healing behavior, have been combined in a single material.

The researchers are led by Michael Kessler, professor in the WSU School of Mechanical and Materials Engineering (MME), and Yuzhan Li, MME staff scientist, in collaboration with Orlando Rios, a researcher at Oak Ridge National Laboratory (ORNL). They report their work in a paper in ACS Applied Materials & Interfaces and have also filed a provisional patent on it.

Smart materials that can react to external stimuli, like light or heat, have a variety of potential applications, including as actuators, drug delivery systems and self-assembling devices. For instance, smart materials could be used to unfurl a solar panel on a space satellite without the need for any external power.

But smart materials haven't yet come into widespread use because they are difficult to make and often can only perform one function at a time. Researchers have also struggled to reprocess smart materials so that their special properties can repeat over and over again.

The WSU research team has now developed a material that displays multiple functions at once, with potential to add more. The team worked with liquid crystals, which they incorporated into an epoxy polymer to produce a liquid crystalline network. The researchers took advantage of the way that liquid crystals change their orientation in response to heat to induce a unique three-way shape-shifting behavior in this network. They also added azobenzene chromophores, which 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 irradiating it with ultraviolet light. The material's movements can be pre-programmed and its properties tailored.

The ORNL researchers used facilities at their Center for Nanophase Materials Sciences to study the mechanisms responsible for the material's unique abilities.

This story is adapted from material from Washington State University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.