Researchers have developed a new 3D printing technique that allows the printing of whole objects and controls the temperature of the chemical reaction to stabilize the process.
Academics in the University of Nottingham’s Faculty of Engineering, in collaboration with the University of California, Berkeley, have developed an enhancement for a type of 3D printing called Volumetric Additive Manufacturing (VAM), which can create whole objects in seconds to minutes. The research has been published in Nature Communications.
VAM works differently to traditional 3D printing, instead of building an object layer by layer, it uses patterns of light to simultaneously produce an entire structure inside a liquid resin. This allows extremely fast printing and the ability to create complex shapes that would be difficult to produce using conventional methods. It also avoids the delamination that can occur between the layers of standard 3D printing techniques, because it avoids sequential layer deposition.
This process has always been limited by the heat produced by the chemical reaction the process relies on, where temperatures can rise by more than 60 °C. This heat can cause the reaction to run out of control, leading to distortions, loss of detail, and it also limits how large, printed objects can be.
Eduards Krumins, a Research Fellow from the Additive Manufacturing Research Group explains: “In this work we have introduced a new chemistry approach to VAM called Reversible Addition Fragmentation chain Transfer (RAFT) polymerization to solve the problem with heat. In simple terms, it acts like a built-in “regulator” for the reaction, both slowing and regulating how the material is formed. This prevents sudden heat spikes and keeps the printing process stable and predictable.”
The research results show a clear reduction in temperature build-up during printing, along with fewer thermal instabilities which can distort printed structures. The team demonstrated the ability to print multiple parts at the same time with gaps as small as about 150 micrometers. This is a great improvement compared to “normal” VAM and so when utilized correctly this could greatly improve the efficiency of the technology.
The RAFT chemistry also allows printed objects to retain reactive sites that can be used afterwards to modify or enhance the material. This opens the door to adding new functions after printing, such as anti-fouling and anti-bacterial coatings.
Crucially, all the original strengths of VAM are still preserved: extremely fast printing, freedom to create complex shapes, and the elimination of weak layers that are common in traditional 3D printing.
Professor Derek Irvine, Professor of Materials Chemistry in the Department of Chemical and Environmental Engineering, adds: “This research represents a step change in volumetric 3D printing: making it more stable, more versatile, while unlocking designs and functions that were previously out of reach.
“Looking ahead it has the potential to be used in a range of applications and an area it could be especially important for is medical applications such as future bioprinting technologies. We are now exploring how to scale the process for larger and more practical industrial real-world use.”