Metal/polymer composite makes for stronger 3D-printed nanostructures
3D printing technology is used not only to build things as large as houses, but also as small as snowflakes. A new material allows the latter to be much stronger than ever before, and to be printed considerably faster.
Developed by scientists at Stanford University, the composite material is intended mainly for use in nanoscale lattice-like structures utilized to protect tiny underlying components (such as those in electronics). It consists of a polymer resin combined with tiny clumps of metal atoms, known as metal nanoclusters.
In an existing process called two-photon lithography, a laser is shone into the liquid resin mixture. Wherever the very center of that beam strikes one of the nanoclusters, a chemical reaction occurs, causing the resin to harden in that specific area. Therefore, by precisely moving the laser beam through the resin, it's possible to build up very small, intricate objects.
When lattices printed from this particular material were tested, they were found to be capable of absorbing twice as much energy as lattices printed from other commonly used materials. Depending on the type of lattice made from the new composite, some excelled at carrying a heavy load without deforming, while others excelled at squishing down to absorb impacts, then springing back into their original undamaged form.
As an added bonus, when the lattices were being printed, the metal nanoclusters allowed the chemical reaction to occur much quicker than it did in other materials that utilized different types of photosensitive molecules. This effect was noted even when a number of different polymers were used in the composite – in one case, when a protein-based polymer was used, items could be printed 100 times faster than had previously been possible with such polymers.
"There’s a lot of interest right now in designing different types of 3D structures for mechanical performance," said Asst. Prof. Wendy Gu, corresponding author of a paper on the research. "What we’ve done on top of that is develop a material that is really good at resisting forces, so it’s not just the 3D structure, but also the material that provides very good protection."
The paper was recently published in the journal Science.
Source: Stanford University