Researchers at the Queensland University of Technology QUT have used intersecting light beams to control chemical reactions in an advanced material, paving the way for future use in 3D printers that print entire layers, instead of single points, at a time. QUT’s Center for Materials Science inter­disciplinary research team includes Sarah Walden, Leona Rodrigues, Jessica Alves, James Blinco, Vinh Truong, and Christopher Barner-Kowollik.

Walden said, light was a particularly desirable tool for activating chemical processes, because of the precision it offered in starting a reaction. “Most of the work QUT’s Soft Matter Materials Group researchers have done in the past with light has been to use a laser beam to start and stop a chemical reaction along the entire volume where the light strikes the material,” she said. “In this case, we have two different colored light beams, and the reaction only occurs where the two beams intersect. We use one color of light to activate one molecule, and the second color of light to activate another molecule. And where the two light beams meet, the two acti­vated molecules react to form a solid material.”

“Normally, in a 3D printer, the inkjet moves around in two dimensions, slowly printing one 2D layer before moving up to print another layer on top. But using this technology, you could have a whole two-dimensional sheet activated, and print the entire sheet at once”, Walden added. Barner-Kowollik said, that such two color activated materials are currently very rare. “This project is about proving the viability of the ink for future genera­tion of printers,” he said. One of the challenges of the project was to find two molecules that could be activated by two different colours of light and then have them react together.

“This is where the inno­vation comes from,” Barner-Kowollik said. “You want a molecule to be activated with one color of light but not the other colour, and vice versa. That’s not easy to find, it’s actually quite hard to find.” His colleague Truong, after much work, was able to find two molecules that reacted to the lights in the required manner and combined to form a very solid material. “In our chemical design, both light activated processes are rever­sible,” Truong said. “Hence we can control exactly when and where the solid material may form”. (Source: QUT)

Reference: S. L. Walden et al.: Two-colour light activated covalent bond formation, Nat. Commun. 13, 2943 (2022); DOI: 10.1038/s41467-022-30002-6

Link: Center for Materials Science, Queensland University of Technology (QUT), Brisbane, Australia