Researchers have developed a one-pot method of vat polymerization by formulating a single resin that hardens into permanent and dissolvable materials when exposed to UV and visible light, respectively. They also created a special 3D printer that emits both types of light, allowing the researchers to print an object and its supports simultaneously.

“Vat photopolymerization is known for its fast and high-resolution printing, but one of the most nerve-wracking parts after printing is manually removing supports for intricate interlocking and overhang structures,” says Maxim Shusteff, one of the study’s corresponding authors. “We are very excited that we can use simple chemistry to solve this issue.”

Vat polymerization produces solid 3D objects after beams of light shine on photoreactive liquid resins. This 3D-printing method is typically fast and inexpensive.

However, intricate items created with vat polymerization usually require supports such as temporary scaffolds, which get attached when the original object is dipped into a second batch of resin. This second step adds time and expense to the process because of the extra resin and extra effort required to remove the temporary supports.

The researchers mixed different components, including acrylate/methacrylate and epoxy monomers, as well as photoreactive substances that absorb both visible and UV light, to create their one-pot resin. During initial tests with the photoreactive substance, they observed that under visible light, the acrylate monomers solidified and formed dissolvable, anhydride-based support materials.

Under UV light, but not visible light, the epoxy monomers hardened into the permanent portion of the object. To dissolve the support material, the researchers added the objects to a sodium hydroxide solution at room temperature, and the permanent object was revealed within 15 minutes. Importantly, the researchers note that the anhydride-based scaffolds degraded into nontoxic compounds. 

In subsequent demonstrations of the new approach, Shusteff and Huang’s team created increasingly complex structures: a checkerboard pattern, a cross, interlocking rings, a ball in a cage, and two balls in a helix.

Research was funded by the U.S. Department of Energy, the University of California Laboratory Research Fees In-Residence Graduate Fellowship, and the Lawrence Postdoctoral Fellowship at Lawrence Livermore National Laboratory.