New Polymer Enhances DLP 3D Printing

A team of researchers at Duke University has created a polymer suitable for use in commercial 3D printers without requiring a solvent. This breakthrough offers significant benefits across various applications. The study was published in Angewandte Chemie International Edition.

Additive manufacturing (AM) has transformed various industries and is set to influence many more in the near future. While the most common AM technology involves 3D printers operating similarly to inkjet printers, another approach, like digital light processing (DLP), constructs objects with light, layer by layer.

DLP, widely used in industrial and dental applications, solidifies liquid resin into a solid form through light exposure, effectively drawing objects layer by layer from a shallow resin pool. A challenge with this method is that resins need to be low in viscosity, like water, to achieve high-resolution prints. Many polymers suitable for DLP are either too viscous or solid, requiring dilution with solvents to reach the necessary consistency.

The use of solvents, however, poses issues, including reduced dimensional accuracy from up to 30 % shrinkage and residual stress from solvent evaporation. This new solvent-free polymer for DLP printing addresses these issues by eliminating shrinkage and improving mechanical properties while also maintaining the material’s capacity to degrade safely within the body.

I wanted to create an inherently thin, low-viscosity material for DLP to use for degradable medical devices. It took a lot of attempts, but eventually I was able to identify optimal monomers and a synthetic technique to create a solvent-free polymer that can be used in a DLP printer without any dilution.

Maddiy Segal, MEMS Ph.D. Candidate, Duke University

Maddiy Segal works in the laboratory of Matthew Becker, the Hugo L. Blomquist Distinguished Professor of Chemistry at Duke.

As one of the first solvent-free resins suitable for DLP printing, Segal was eager to assess its properties. She was thrilled to find that test parts showed no shrinkage or distortion and were overall stronger and more durable than those made with traditional solvent-based resins. Her findings represent one of the first empirical demonstrations of improved mechanical properties due to the elimination of solvents in the DLP 3D printing of degradable polymers.

To create her new polymer, Segal examined the structure and properties of resins from the Becker Lab and other sources, systematically adjusting monomers and chain lengths through a step-by-step empirical approach. She essentially used a “guess and check” strategy, tweaking monomers and “recipes” until she achieved the desired low-viscosity polymer.

This method is somewhat like cooking a recipe: specific ingredients are mixed, heated, and tested repeatedly until the desired result is achieved. Altogether, Segal experimented with about 60 different combinations before successfully creating the final product.

Besides making a material that didn’t shrink and was stronger, I also wanted it to be useful for medical applications. I’m trying to make prototype devices that are both biocompatible and degradable. Eliminating toxic solvents from the process will help me do that.

Maddiy Segal, MEMS Ph.D. Candidate, Duke University

Segal’s primary goal with this research is to apply her technique to biodegradable medical implants. Currently, certain temporary implant materials are non-degradable, requiring multiple surgeries for implantation and removal. Segal aims to develop implants that can degrade naturally within the body, reducing the need for additional procedures.

Devices made from this material could be implanted and designed to break down over time, eliminating the need for surgical removal. Potential applications include use as a bone adhesive to temporarily hold fractures or in soft robotics, where a soft, degradable material is essential.

This kind of material is what makes this particular application the primary goal of my work. And in reality, this technique could be used for any sort of implant that you would want to degrade after some time and not stay there forever.

Maddiy Segal, MEMS Ph.D. Candidate, Duke University

This research is funded by the National Institutes of Health (1R01HL159954-01). Duke University has also filed a provisional patent application for the technology.

Journal Reference:

Segal, M. I., et al. (2024). Synthesis and Solvent Free DLP 3D Printing of Degradable Poly(Allyl Glycidyl Ether Succinate). Angewandte Chemie International Edition. doi.org/10.1002/anie.202414016.