A new resin expands the scope of volumetric printing

A new light-sensitive polymer resin gives researchers more control over 3D-printed objects.

Since its inception in the early 1980s, 3D printing technology has emerged as a futuristic and revolutionary means of manufacturing. Among the many innovations is a technique called volumetric additive printing, in which an entire 3D object is is solidified from a photosensitive liquid material by irradiating it with different patterns of light.

This technique is highly innovative because it overcomes many of the drawbacks of layer‐by-layer fabrication of conventional 3D printers, such as long build times and rough surfaces. The types of materials available are also broader, having fewer constraints on viscosity and reactivity compared to layer printing.

In an article recently published in Advanced Materials, a team of researchers led by Maxim Shusteff of Lawrence Livermore National Laboratory reported a highly tunable strategy using a new thiol-ene photoresin.

Thiol-enes are polymers formed through the polymerization between a thiol and an alkene to form a thioether. They have drawn significant attention in recent years owing to the high degree of control and tunability that researchers can exert over the reaction (something that is now always easy to do in a polymerization), and yield polymers with excellent mechanical properties.

In their study, the team applied thiol-enes to create a new class of resins to expand the versatility of volumetric printing. Using a 3D distribution of light, they were able to cast images generated using an algorithm onto the resin, triggering polymerization at specific locations to build 3D objects, like rings.

An important feature of the thiol-ene resin is the fact that it follows a “a nonlinear response to the curing illumination”, meaning the material has an energy threshold that allows the polymerization reaction that forms the hardened polymer to be highly controlled. Regions that are not irradiated with the right amount of energy will remain liquid and can later be poured away afterward.

“The widely adjustable and bulk‐equivalent mechanical behavior of this thiol‐ene resin system represents a significant advancement for VAM, introducing a major class of polymer materials for use with the volumetric 3D printing paradigm,” wrote the authors in their paper. “By varying the relative monomer composition within thiol‐ene resins, the modulus and toughness can be varied.”

The team has plans to use these thiol‐ene materials as functional biological scaffolds, as the unreacted thiols can be used for surface functionalization. Though continued improvements between the algorithm-defined energy estimates and experimental exposures to further enhance the technique’s capabilities, the team is optimistic that expanding material options for 3D printing technologies will pave the way for better control and complexity in 3D-printed materials.

Reference: Caitlyn C. Cook, et al., Additive Manufacturing: Highly Tunable Thiol‐Ene Photoresins for Volumetric Additive Manufacturing, Advanced Materials (2020). DOI: 10.1002/adma.202003376

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