At the University of Queensland’s Australian Institute for Bioengineering and Nanotechnology (AIBN), researchers have printed 4D structures using liquid metal polymers that can be coaxed into performing a range of mechanical tasks with infrared lasers.
“4D printing takes traditional 3D printing and adds a new dimension — the dimension of time,” Zhang said. “Our method allows us to produce smart liquid metals that can be customized, shaped, and prompted to change over time without needing wires or circuits.
4D printed objects are usually prepared with a 3D printer using specific ingredients that give the finished product new qualities and abilities. Previous research has demonstrated the utility of nanomaterials in printing polymers, though challenges with establishing the necessary percolated network have led to the flexibility and the level of shape change being compromised.
The current work used gallium-based spherical liquid metal nanoparticles to prepare printing resins that respond to near-infrared light. The researchers grafted the liquid metal nanoparticles with reversible addition-fragmentation chain transfer agents to enable polymerization for 3D printing. The grafted nanoparticles, importantly, can be directly prepared in 3D printed resins, allowing a one-step printing approach.
The resulting objects can be stimulated with a NIR laser to guide the materials to bend, grab, and release items.
This could mean a number of applications across the aeronautical engineering and medical device sectors, including coronary stents, artificial muscles, and other devices that adapt and change shape inside the body.
More broadly, Qiao said the ability to customize and shape materials after they had been printed would lead to wider manufacturing breakthroughs and consumer innovations, from climate-reactive clothes and building materials to self-assembling furniture.
“4D printing is a rapidly evolving field that is really only limited by imagination,” Qiao said.
The research was published in Nature Communications (www.doi.org/10.1038/s41467-023-43667-4).