Lab explores new resins for light-based 3-D printing

A team from Lawrence Livermore National Laboratory (LLNL) simulated the cross-linking of 3-D printed polymer networks, a critical step towards the development of novel functional resins for light-based 3-D printing techniques, including lithography. two photons (TPL) and volumetric additive manufacturing (VAM).

The team used molecular dynamics simulations to study, at the microscopic level, the kinetics and topology of three different molecules of the same reactive group (acrylate) but containing different non-reactive components. The researchers found that differences in the dynamics and structure of the resulting cross-linked polymers, constructed using the TPL and VAM processes, were the result of differences in the non-reactive parts of the molecules. The research appears in the October 15 issue of Journal of Physical Chemistry B and is available online as additional coverage.

The researchers said the knowledge gained from the study opens the door to rationally designed photoresists and will help them in their quest to design new custom photosensitive resins capable of pushing the boundaries of TPL and VAM developed by LLNL. These techniques generate three-dimensional objects by projecting light modeled in liquid resins, causing them to harden in the desired points in seconds. The resins used in these processes often contain different molecules with the same reactive functional groups and their formulation is based on trial and error methods, with the results treated as trade secrets.

“Our combination of molecular dynamics simulations and mathematical graph theory allows us to modify or perturb the chemistry and physics of the molecules that serve as building blocks in AM techniques such as TPL and VAM and see the impact on the resulting polymer,” he said. explained John Karnes, the lead author of the article. “Since we can see every atom in these simulations, we are starting to develop an insight that bridges the gap between microscopic network topology and macroscopic behavior, such as understanding the relationship between intramolecular loops or cycles and where the liquid resin gels to form the solid molded part. “

LLNL materials scientist Juergen Biener said the team is continuing work by exploring longer lengths and time scales, simulating mechanical testing of printed parts, and modeling other types of curing of interest to LLNL.