Self-healing 3D printed plastic can repair itself… using only light

UNSW engineers have demonstrated a way how 3D printed plastic can self-heal at room temperature using only light.

Professor Cyrille Boyer and his team, Dr. Nathaniel Corrigan and Mr. Michael Zhang, from the UNSW School of Chemical Engineering have shown that adding “specialty powder” to the liquid resin used in the printing process can help make repairs quick and easy later should the material break.

This can be done easily by shining standard LED lights on the printed plastic for about an hour, causing a chemical reaction and fusion of the two fragments.

The whole process makes the repaired plastic even stronger than it was before it was damaged, and it is hoped that advancement and commercialization of the technology will help reduce chemical waste in the future.

Broken plastic parts do not have to be disposed of or even recycled and can easily be repaired even if they remain embedded in a component with many other materials.

The team’s research results have now been published in the journal Angewandte Chemie International Edition.

Reduce plastic waste

“You can use this technology in many places where you use a polymer material. So if a component fails, you can fix the material without throwing it away, ”said Dr. Corrigan.

“The benefit for the environment is obvious because you don’t have to re-synthesize a brand new material every time it breaks. We extend the lifespan of these materials, which reduces plastic waste. “

The powdered additive the UNSW team uses is a trithiocarbonate known as a Reversible Addition Fragmentation Chain Transfer (RAFT) agent, originally developed by CSIRO. The RAFT agent enables the reorganization of the nanoscopic network of elements that make up the material and allows the fragments to be fused together.

It does this in about 30 minutes if UV LED light is shone directly on the broken plastic, with full healing occurring in about an hour.

UNSW researchers have shown how 3D printed objects that have been treated with a trithiocarbonate, such as this violin, can heal themselves when placed under UV light. Photo delivered

Experiments, including on a 3D-printed violin, show that the strength of the self-repaired plastic has been completely restored compared to its original unbroken state.

The team said the process could be commercialized because of the simplicity and speed of their system compared to existing methods of repairing defective 3D printed materials.

“There are other methods that do this, but they rely on thermal chemistry to repair the material and it usually takes about 24 hours and multiple heating cycles to get the same result,” said Dr. Corrigan.

“Another limitation is that you need an oven that is heated to high temperatures and of course you cannot repair the plastic material on site – you would have to disassemble it from the component first, which adds complexity and delay.

“With our system, you can leave the broken plastic in place and illuminate the entire component with light. Only the additives on the surface of the material are affected, this is easier and also speeds up the entire process. “

Professor Boyer says the new technology could potentially be used in a number of applications where advanced 3D printed materials are currently used in specialized high-tech components.

This includes wearable electronics, sensors, and even some shoe manufacturers.