Materials that self-heal and shapeshift

New innovations in physics and chemistry

Graphic by Bram Keast

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Materials science is the study of new materials through the lens of interdisciplinary science and engineering. The discipline requires knowledge of chemistry, physics, and engineering to create innovative materials that can make cars lighter, tools stronger, or solar panels more efficient.

Newly-developed material technology can be disruptive in nature, meaning it can lead to creating improvements that can completely change and displace old ones suddenly. Here’s a look at a few interesting developments in the world of materials science.

 

Self-healing and self-stiffening material

Researchers at Rice University in Houston, Texas have developed what they call a self-adaptive composite (SAC) by combining polymers and solvent and heating them. After the excess liquid is evaporated away, a porous, viscous material is left behind with interesting properties. When the material is compressed or put under stress, it is able to return to its original shape.

The material is made using polyvinylidene fluoride (PVDF), a liquid, which is encapsulated by polydimethylsiloxane (PDMS) to form tiny spheres. Creating a spongey structure, the material is able to absorb stress and return to its original shape by allowing the spheres to move around each other, but still remain attached. It’s similar to how water molecules are able to easily move between each other.

The material’s stiffening and absorption properties can be adjusted by adding more liquid or solid. The researchers believe the material will prove useful in biomedical and structural engineering applications.

The study was published in the American Chemical Society Journal and received support from the Air Force Office of Scientific Research and the Department of Defense.

Shape-shifting material

A team from Zhejiang University, China have created a material which can shift into multiple forms by applying or removing heat. The material is programmed to take on various shapes through covalent bond exchange.

The material uses two properties to achieve this: elastic deformation and plastic deformation. Elastic deformation is a temporary deformation of a material, while plastic deformation is more permanent.

The material reacts and shape shifts when different temperatures are applied. This causes the covalent bonds to change their behaviours.

In a video demonstration online, the researchers show a piece of material that starts as an origami swan. When exposed to infrared heating, it flattens out in a square piece of material. Further exposure to the infrared heating then causes the material to shape itself into an origami flower. All of this is done through heat exposure alone, using the properties of the material.

Shape shifting materials can be useful in medicine by creating temperature-sensitive medical devices.