outtakes

Reflections on academic life

Shape shifting plastics

Shape-shifting plastics—a much-favoured material for superheroes and über spies —are now possible thanks to a fortuitous discovery at UBC.

Jayachandran Kizhakkedathu, an investigator at UBC’s Centre for Blood Research, noticed something intriguing in his quest to develop new surface coatings for medical implants and storage containers to hold blood or biosensors.

Assoc. Prof. Kizhakkedathu found that certain coatings caused the plastic film to morph and then revert back to its original shape.

To solve the mystery, he invited Srikantha Phani, Canada Research Chair in Dynamics of Lattice Materials and Devices, to design a series of experiments.

Recently detailed in the journal Angewandte Chemie, Phani and Kizhakkedathu developed a novel protocol for grafting nanoscale polymer chains to the surface of polyvinylchloride (PVC) film. Polymers are large molecules composed of repeating structural units made up of small molecules that are chemically bonded together.

The researchers coated a small strip of PVC on one side with polymer chains. The team observed that the plastic curls into a loop when submerged in water.  And when the PVC strip was coated on both sides with polymer chains and dipped into water, the plastic expanded and stretched up to 10 per cent beyond its original length.

“As far as we know, we’re the first group in the world to show this is possible in soft material systems, says Phani, assistant professor of mechanical engineering.

Phani explains the grafted polymer chains on the surface resemble toothbrush bristles and can react to external stimuli such as heat, light, electricity and pH.
“The response translates into a mechanical reaction and force that causes the
plastic to bend and change shape.”

“This is significant for future biomedical possible uses such as catheters that go into the human body, artificial muscles or sensors,” says Kizhakkedathu, who also teaches in the departments of chemistry and pathology.

Collaborating on the project are postdoctoral fellow Yuquan Zou at the Centre for Blood Research, Prof. Donald Brooks, who is jointly appointed to the departments of chemistry and pathology, and Dept. of Mechanical Engineering undergraduate student Adriel Lam.

Videos of the UBC experiments can be viewed at:
www.sites.mech.ubc.ca/~dal/Media.php

To read the Angewandte Chemie paper, visit:

www.sites.mech.ubc.ca/~phani/Publications/YZ_AL_JKN_SP_Soft%20Materials.pdf

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