When most people hear the word latex, gloves, or paint come to mind. Well, “latex” actually refers to a group of long, repeating chains of molecules (polymers) that are coiled within nanoparticles dispersed in water. It is an elastomer. Any rubbery material is an elastomer. They’ve been next to impossible to use in additive manufacturing because they are incredibly fragile and challenging for chemists to alter.
But now, it’s possible to 3D print latex rubber thanks to an interdisciplinary group of mechanical engineering and chemistry researchers from Virginia Tech. They managed the feat through a combination of custom-made advanced printing hardware and some serious chemical modifications to the material.
Co-principal investigator Timothy Long said:
This project represents the quintessential example of interdisciplinary research. Neither of our labs would be able to accomplish this without the other.
The 3D printer was embedded with a computer vision system to print accurate, high-resolution features of the latex. Meanwhile, the high-performance material was made printable through the use of a molecular scaffold that gave the solution stability. The modifications also made the liquid photocurable so that UV exposure techniques (called vat photopolymerization) could be used to cure the desired form.
The breakthrough unlocks the ability to print elastic materials with complex shapes, which could be extremely useful for applications such as medical devices, soft robotics, and shock absorbers.
Viswanath Meenakshisundaram, a mechanical engineering Ph.D. student who worked on the printer, said:
Latexes are in a state of Zen. If you add anything to it, it’ll completely lose its stability and crash out.
The molecular scaffolding held the latex particles in place, but then other compounds had to be added in so that the liquid would harden when the UV light hit it. The camera had to be added to the (already) custom printer because the fluid latex particles caused scattering outside of the projected UV light, which resulted in inaccurate printing parts. The camera observes how the light interacts with the material and corrects any distortion of print parameters with the help of a custom algorithm.
The team tested their developments and found that the final 3D printed latex parts exhibited advanced geometries with robust mechanical properties. They succeeded in pushing the boundaries of printed material performance in a way nobody’s ever done before. They envision the technology evolving quickly so that very soon, we’ll be able to produce robust and flexible custom rubber parts of any shape.
The world of 3D printing is evolving exponentially – with other success stories including two-story houses being printed in one go, titanium strength aluminum, beating human hearts, cannabis drinks, a home-made Lamborghini, an electric motorcycle, entire neighborhoods for the poor, sustainable housing in Italy, outdoor concrete furniture, and so much more. It’s exhilarating!
