Materials Expand Volumetric 3D Printing

A new class of materials adapted by researchers at Lawrence Livermore National Laboratory (LLNL) enable nearly instant production through volumetric 3D printing and expanding the range of material properties achievable with the technique.

The materials are called thiol-ene resins, and they can be used with LLNL’s volumetric additive manufacturing (VAM) techniques, including computed axial lithography (CAL), which produces objects by projecting beams of 3D patterned light into a vial of resin. As light cures the liquid resin into a solid at the desired points in the volume, the vial spins. The resin is drained, leaving the 3D object behind. The whole process takes place in a matter of seconds.

Using a custom volumetric additive manufacturing 3D printer, Lawrence Livermore researchers were able to build tough, strong, stretchable, and flexible objects nearly instantly from a class of materials known as thiol-ene resins. Courtesy of Maxim Shusteff/LLNL.

The researchers worked previously with acrylate-based resins that produce brittle objects using the CAL process. The new resin, created through the careful balancing of three different types of molecules, is more versatile, giving the researchers a flexible design space and a wider range of mechanical performance. The researchers were able to build tough and strong materials, as well as stretchable and flexible objects using a custom VAM printer at LLNL.

“These results are a key step toward our vision of using the VAM paradigm to significantly expand the types of materials that can be used in light-driven 3D printing,” said LLNL engineer Maxim Shusteff, principal investigator and head of a Laboratory Directed Research and Development project in advanced photopolymer materials development.

The researchers also demonstrated the first example of a method for the design of the 3D energy dose delivered into the resin to predict and measure it. This allowed the scientists to successfully print 3D structures in the thiol-ene resin through tomographic volumetric additive manufacturing. The demonstration created a common reference for controlled 3D fabrication and for comparing resin systems, the researchers said.

The work, they said, represents a significant advancement for volumetric additive manufacturing as they work toward producing high-performance printed engineering polymers, with particular emphasis on using thiol-ene in biological scaffolds. Thiol-ene materials have shown promise for applications including adhesives, electronics, and biomaterials, the researchers said.

“By implementing a nonlinear threshold response into a broad range of chemistries, we plan to print with resins such as silicones or other materials that impart functionality,” said LLNL materials engineer Caitlyn Cook.

The researchers intend to improve the agreement between computational models and experiments and apply photochemical behavior to the computed tomography reconstructions that produce the 3D models used to build objects.

The research was published in Advanced Materials (www.doi.org/10.1002/adma.202003376).