Forward-looking: Researchers from California and South Korea have discovered a way to use a water-soluble polymer as a new, recyclable material for 3D printing. This polymer can also be combined with other materials, such as carbon nanotubes, to enhance its robustness. This innovation could lead to more sustainable components for electronic circuits and bio-delivery systems.
There are various methods of 3D printing using raw materials like filaments and liquid polymers. However, these processes often require multiple steps and sometimes complex instrumentation to create structures. For example, making a structure with Fused Deposition Modeling (FDM) requires melting and cooling the filament. Other methods, like resin-based 3D printing, require ultraviolet light to cure the liquid polymer.
The polymer known as PNIPAM (poly(N-isopropyl acrylamide)) was first synthesized in the late 1950s and is used in various applications today, including biosensing, controlled drug delivery, and water purification. Researchers from the University of California, San Diego, and Hanyang University in South Korea discovered that PNIPAM can be used as a recyclable ink for 3D printers. This breakthrough comes hot off the heels of another 3D printer innovation called CHARM3D, developed by researchers in Singapore.
The researchers used a method called the salt-out effect. Introducing PNIPAM to a calcium chloride salt solution forms physical crosslinks, which lead to almost instant solidification without the need for heat, light, or toxic solvents. The 3D-printed PNIPAM structure can then be dissolved in water and reclaimed for recycling and reuse.
There were concerns that PNIPAM's water-soluble and temperature-sensitive properties might limit its applications. However, the good news is that PNIPAM can be combined with other materials to enhance its thermal and mechanical properties.
In one example, the researchers combined PNIPAM with carbon nanotubes to create an electrically conductive circuit, which was used to power an LED light. After the test, they dissolved the circuit and reclaimed the PNIPAM/CNT material.
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This demonstrates the potential of applications using water-soluble circuits, which could start a new wave of recycling electronics and reducing e-waste.
Maybe in the not-so-distant future, technology manufacturers can flex their use of PNIPAM/CNT-based circuits in their smart devices.