Researchers at UNSW Sydney have expanded upon their novel 2014 discovery of a new polymerization method to create a new eco-friendly “living” polymer via 3-D/4-D printing. Four-dimensional printing is a subset of 3-D printing where the printed object can transform its shape in response to certain conditions.
“For example, the 3-D object starts as a flat plane and when exposed to certain conditions, it will start to fold – that’s a 4-D material. The fourth dimension is time,” explains Nathaniel Corrigan, co-first author of the paper published in Angewandte Chemie International Edition last week.
In 2014, Cyrille Boyer and his team at UNSW Sydney developed PET-RAFT (Photoinduced Electron/energy Transfer-Reversible Addition Fragmentation Chain Transfer) polymerization, a way to make controlled polymers using visible light via the RAFT polymerization technique.
This new research goes beyond that discovery with implications in recycling, drug delivery and biomaterials.
“Controlled polymerization has never been used in 3-D and 4-D printing before because the rates of typical controlled polymerization processes are too slow for 3-D/4-D printing, where the reaction must be fast for practical printing speeds,” Boyer said. “After two years of research and hundreds of experiments, we developed a rapid process compatible with 3D printing. In contrast to conventional 3-D printing, our new method of using visible light allows us to control the architecture of the polymers and tune the mechanical properties of the materials prepared by our process.”
Everyday applications
The main benefit of Boyer and his team’s new 3-D/4-D printing method is the ability to repair and reuse plastics. Rather than recycling an item to have it broken down and reconstructed, this light-controlled process allows the material to repair itself. At the very least, less plastic will end up in landfills. At the most, no plastic will end its life in an environmentally harmful landfill.
But polymers are not just plastic, they can be biological as well, such as DNA. Traditionally, 3-D printing has been difficult to utilize in biomedical applications since harsh conditions, like strong UV light and toxic chemicals, are a required. However, the PET-RAFT method overcomes this limitation.
“Using heat above 40 degrees kills cells, but for visible light polymerization we can use room temperature, so the viability of the cells is much higher,” said Corrigan.
According to Boyer, objects made with this new process could more easily be used in advanced bio-applications/biomedicine, microelectronics, and any other niche applications that require advanced polymers.
Boyer and his team are still working to perfect their new process—and taking steps to allow non-experts users to produce living materials.
“We want to explore our system to find and address any limitations to allow for better uptake and implementation of this technology,” Boyer said. “There is so much we can do by combining 3-D and 4-D printing with controlled polymerization to make advanced and functional materials for many applications to benefit society.”