An adaptive composite that heals itself

Materials World magazine
,
1 Feb 2016

60 seconds on...a shape-changing, self-healing material

What is it?

The creators of this material have named it a self-adaptive composite (SAC). When cracked, the matrix heals and, after compression, returns to its original form. 

Who created it?

A team from Rice University, USA, led by materials scientists Pulickel Ajayan and Jun Lou.

What is it made out of?

Polyvinylidene fluoride (PVDF) makes up both the liquid interior and the solid shells of the spheres, which are coated with viscous polydimethylsiloxane (PDMS). The liquid PVDF in the micrometre-scale spheres enhances their viscoelasticity, while the shell and coating make them stick together. They can slide past each other as the material is compressed, but remain attached to each other.

How is it made?

The polymer components begin as powder and viscous liquid. A solvent and controlled heating are applied and the PDMS and PVDF stabilise into solid and 'gooey' spheres that provide the reconfigurable structure, while the solvent evaporates.

What could it replace?

The SAC provides increased mechanical strength compared with other self-healing deformable materials such as hydrogels, giving it potential in medical and structural applications. The shells of the spheres are also more resistant to cracking than competing materials, preventing liquid from leaking out of the spheres.  

To read the paper A Solid-liquid Self-adaptive Polymeric Composite, published in Applied Materials and Interfaces, visit bit.ly/1UM7kKd

To watch the material in action, download the Materials World app by visiting app.materialsworld.org