A fast-acting molecular probe that changes color senses when material will fail

Beckman Institute director Jeffrey Moore, left, postdoctoral researcher Hai Qian and materials science and engineering leader Nancy Sottos led a team of Illinois engineers to develop a new fast-acting, reversible polymer that changes color when it soon collapses. Credit: Photo by L. Brian Stauffer

Materials containing special polymer molecules may one day be able to warn us when they will fail, the researchers said. Engineers from the University of Illinois Urbana-Champaign have improved their previously developed force-sensitive molecules, called mechanophores, to produce a reversible, fast, and vibrant color change when force is applied.

A new study led by postdoctoral researcher Hai Qian, professor of materials science and engineer and leader Nancy Sottos and director of the Beckman Institute for Advanced Science and Technology Jeffrey Moore was published in the journal Chem.

Moore’s team has been working with mechanophores for more than a decade, but past efforts have created molecules that have reacted slowly and returned to their original state, if they had any at all. This inability to create a reaction similar to on and off has limited their use as molecular probes that continuously report the mechanical state of materials, the study reports.

“The color change is the result of the stress applied to the connections that connect the mechanophores to the polymer chain,” Qian said. “We now bind mechanophores to polymer chains using a different arrangement scheme, called the oxazine structure. The new structure allows instant and reversible color change, so instead of the polymer slowly darkening over time, the color changes rapidly when force is applied and disappears when force is applied. remove. “






Materials containing new mechanophores could be used as stress sensors that allow researchers to study the effects of stress on materials before they fail.

“Quick response and reversibility will allow engineers to better monitor, quickly detect, and respond quickly to an overly stressed structure in the lab and ultimately in the field,” Sottos said.






A long-standing challenge in materials science has been the observation of mechanical loading and other stresses in materials at the level of a single molecule. Although this progress cannot be made, Moore says the goal is closer to developing this new type of mechanophore.

“There is still work to be done, but this progress opens the door to a detailed insight into what is happening at the molecular level in all types of materials,” Moore said. “In the field of biomechanics, for example, we see this research as a springboard to better monitor how our bodies respond to external forces from the cellular level and beyond.”


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More information:
Hai Qian et al., Rapid, reversible mechanochromism of regioisomeric oxazine mechanophores: Development of in situ reactive force probes for polymeric materials, Chem (2021). DOI: 10.1016 / j.chempr.2021.02.014

Journal information:
Chem

Provided by the University of Illinois at Urbana-Champaign

Citation: Fast-acting, color-changing molecular probe senses when material will fail (2021, March 25) downloaded March 25, 2021 from https://phys.org/news/2021-03-fast-acting-color-changing -molecular-probe-material.html

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