Researchers from Queensland University of Technology (QUT), Ghent University (UGent) and Karlsruhe Institute of Technology (KIT) have developed a dynamic reprogrammable material whose structure chances under green LED light.

The new dynamic material, developed by the international research team, was formed with naphthalenes and the coupling molecules triazolinediones (TADs). Once placed under shining green LED light, the material would remain stable and strong. When the light is off and the material remains in darkness, the chemical bonds of the network structure broke up and the material became soft and liquefied.

(Macroscopic Demonstration of Light-Stabilized Dynamic Behavior; image; Queensland University of Technology)

According to the study, the hard-to-soft process could be repeated with the flick of the switch, and the light could be dimmed to modulate the mechanical properties of the material. The following research will further search for other chemical combinations to see if the same result can be achieved.

Professor Barner-Kowollik, at QUT's Science and Engineering Faculty, said what makes the discovery unique is that light is used as the trigger to stabilize, rather than destroy, chemical bonds. Thus, the researchers have coined a new term, light-stabilized dynamic materials (LSDMs).

The research is significant because usually what scientists achieved is the opposite result. The team noted that different wavelengths of light or heat are used to break up the polymer molecule chains instead of forming the structure.

"However, in this case, we used green LED light to stabilize the network. The trigger to break up the network, make it collapse and flow away is actually the mildest one of all: darkness. Switch the light back on and the material re-hardens and retains its strength and stability,” mentioned the researchers.

They believe that new dynamic material could potentially be used as a 3D printing ink to print temporary, easy-to-remove support scaffolds. This would overcome one of the current limitations of the 3D process to print free-hanging structures.