An unbreakable screen that generates electricity
Imagine a cellular phone that recharges to the rhythm of your thumbs! Better still, if the screen breaks, it repairs itself! This is the research project carried out by Twinkal Patel, a PhD student in the Oh Research Group at Concordia University.
Led by Professor John Oh, the Oh Research Group specializes in the self-assembly of nanomaterials. In addition, by exploring the chemical properties of polyurethane-based car paints, John Oh and Twinkal Patel came up with the idea of using these properties to engineer a polyhindered urea* (PHU)-based phone screen that repairs itself. By working on the synthesis conditions, Twinkal Patel has obtained a network of PHU polymers called vitrimer, that is, a material of glassy appearance but which retains a certain malleability. For example, if it is bent, the network can rearrange its links to regain its original form. This is what makes it self-healing. In fact, when Twinkal Patel rubs its polymer with sandpaper, 50% of the scratches are repaired in 30 minutes at room temperature. With an additional heat treatment, the repair is complete.
Twinkal Patel had a second bright idea: adding to its polymer a coating made of another material to produce a triboelectric effect. This effect is the one that generates static electricity when you rub two materials together.
“If you rub a balloon on your hair, static electricity forms. This is what happens at the nanoscopic scale, it creates an electric charge on both materials”
explains Twinkal Patel. The electricity must then be transferred to the phone battery. We will not rub our cellular phone on our hair to recharge it; all it takes is that two materials come into contact briefly and repeatedly, and we will get triboelectricity. Repeated contacts like tapping our thumbs on the screen!
Yes, but if the screen breaks and repairs, will it still be able to produce electricity? The advantage of vitrimers is that they retain their physical properties during their remodeling. Twinkal Patel has verified this. “We measured the voltage. Then we scratched the screen with sandpaper. Because of the scratches, there was less contact between the two materials and the voltage decreased. The polymer was allowed to repair itself and the voltage returned to its original level,” she said.
Twinkal Patel has developed vitrimeric PHU networks and demonstrated its electrical and self-healing properties, but she and her colleagues have yet to integrate this revolutionary screen into a phone. The Oh Research Group does not manufacture telephones, but collaborates with Korean academics and industrial partners on this project. Twinkal Patel is therefore preparing to go to Korea to see her self-healing screen take shape.
Twinkal Patel was awarded a Concordia Graduate Student Scholarship to carry out her research. She has also received a Globalink FRQNT-MITACS grant for her upcoming research internship in Korea.
*That is, a urea molecule carrying bulky chemical groups that replace tinier hydrogen atoms.
Further readings
T. Patel et al., Self-Healable Reprocessable Triboelectric Nanogenerators Fabricated with Vitrimeric Poly(hindered Urea) Networks ACS Nano, 2020, 14, 9, 11442–11451
Original French text by Valérie Levée.
Translated by Valérie Levée and Matteo Duca, Development and scientific affairs director of QCAM
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