14 DAY TRIAL // Researchers at the University of Illinois have created a new brand of polymers, which is able to shift color when it is stressed beyond its capacity, or overloaded. The innovation could benefit a wide range of applications, from building structures to designing more efficient climbing ropes or parachute cords. Basically, the new materials are able to sense the force that is being applied to them, and to optically alert engineers if it's within normal parameters, or if their assigned strain is exceeded.
“This offers a new way to build function directly into synthetic materials. And it opens the door to creating mechanophores that can perform different responsive functions, including self-sensing and self-reinforcing, when stressed,” the UI Willett Professor of Materials Science and Engineering Nancy Sottos explained, as quoted by PhysOrg. Mechanophores are mechanically active molecules within the very structure of the polymer, which are able to trigger a series of chemical reactions when they are acted upon.
In previous lab studies, the expert, working together with UI colleagues, managed to demonstrate the same properties in solution-based polymers, but now they have succeeded in creating a version of the mechanophores that can also operate in solid polymers. Details of the team's accomplishments are published in the May 7th issue of the scientific journal Nature. The experts have also mentioned the fact that the basic principle of these molecules, known as mechanochemical transduction, is the basis for a number of physiological human processes as well, including touching, hearing, balance and tissue growth.
“Mechanical stress induces a ring-opening reaction of the spiropyran that changes the color of the material. The reaction is reversible, so we can repeat the opening and closing of the mechanophore. Spiropyrans can serve as molecular probes to aid in understanding the effects of stress and accumulated damage in polymeric materials, thereby providing an opportunity for assessment, modification and improvement prior to failure,” the lead author of the Nature paper, UI graduate research assistant Douglas Davis, added.
“We've moved very seamlessly from chemistry to materials, and from materials we are now moving into engineering applications. With a deeper understanding of mechanophore design rules and efficient chemical response pathways, we envision new classes of dynamically responsive polymers that locally remodel, reorganize or even regenerate via mechanical regulation,” Sottos concluded.