Nanomachines are already useful for delivering medication and serving as computer memories at the nanometer scale. But thanks to advance 3D printing techniques, researchers at Dartmouth College have found a way to make nanomachines useful at the human scale.
“Up until now, harnessing the mechanical work of nanomachines has been extremely difficult,” says Chenfeng Ke, assistant professor of chemistry at Dartmouth and the principle investigator for the research. “We are slowly getting closer to the point that they tiny machines can operate on a scale that we can see, touch, and feel.”
The Dartmouth researchers designed and synthesized mechanically interlocked molecule-based gels with properties desirable for 3D printing. They printed lattice-like 3D structures using hydrogen bonding interactions between nanorings. During the printing process, the researchers discovered the architecture of the structures can be reversibly deformed and reformed through solvent exchange that switches the threaded ring structure between random shuttling and stationary states at the molecular level.
The design, which is outlined in the March 22 online edition of Angewandte Chemie, the journal of the German Chemical Society, is based on research that turned MIMs into work-performing machines at the nanoscale. Heat and altered pH levels could result in movement within a structure, known as a rotaxane, composed of rings on a molecular axle, much like the way beads are threaded onto a string. The shuffling or sliding of these rings along the axle causes the molecules to change shape and store energy.
MIMs are already used as molecular shuttles, switches, muscles, and pumps, according to the paper. Chemists, however, have been stumped about how to order the random positions of the MIMs. Establishing this order is necessary to keep the structures from canceling out each other’s mechanical movement so their molecular motions can be strengthened.
The researchers used this concept to develop a smart material capable of lifting a dime weighing 2.268 grams, about 15 times the weight of the structure lifting it. The nanomaterial was able to lift the dime 1.6 mm. For comparison’s sake, that’s like a human lifting a car, the researchers say.
“Creating nanomachine-based smart material is still extraordinarily complex, and we are only just beginning, but this new technique could allow the design and fabrication of complex smart devices that are currently beyond our grasp,” says Ke.
One area Ke would like to explore is robotics. He believes by adding contracting and twisting motions to the rising motion, molecular machines could be used as soft robots that can complete tasks traditional conducted by human hands.
“Our work provides the first design principle to add 3D printability to nanomachines,” says Ke, who completed his postdoctoral research with 2016 Nobel laureate Sir Fraser Stoddart. “Importantly, we have also transformed molecular motions to macroscale to do useful work.”
Filed Under: 3D printing • additive manufacturing • stereolithography, Materials • advanced
