3D printing is amazing enough on its own, but when it becomes 4D printing, it’s even more incredible. The fourth dimension in 4D printing is time, and 4D printed items can change shape or self-assemble over time, with some kind of a stimulus. 4D print technology continues to become more advanced and complex, and researchers at Dartmouth College have advanced it further with the development of a smart ink that changes both shape and color.
“This technique gives life to 3D-printed objects,” said Chenfeng Ke, Assistant Professor of Chemistry at Dartmouth. “While many 3D-printed structures are just shapes that don’t reflect the molecular properties of the material, these inks bring functional molecules to the 3D printing world. We can now print smart objects for a variety of uses.”
To create the smart ink, the researchers used a polymer-based “vehicle” that integrates intelligent molecular systems into printing gel and transfers their functions from the nanoscale to the macroscale. This results in a printed object with a molecular design that is programmed to transform itself. It can change shape with a chemical stimulus, for example, or change color if a light is shined on it.The researchers used a combination of new techniques in both pre- and post-printing to reduce 3D printed objects to one percent of their original size at 10 times the resolution. They were also able to get the objects to repeatedly expand and contract using supramolecular pillars.
“This is something we’ve never seen before,” Ke said. “Not only can we 3D print objects, we can tell the molecules in those objects to rearrange themselves at a level that is viewable by the naked eye after printing. This development could unleash the great potential for the development of smart materials.”
The smart ink can print at a 300-micron resolution, but the final product is 30 microns.
“This process can use a $1,000 printer to print what used to require a $100,000 printer,” said Ke. “This technique is scalable, widely adaptable and can dramatically reduce costs.”
The new process allows designers to retain specific molecular functions and alignments in a material and then convert them for 3D printing. By reducing the size of the object after printing, researchers can preserve functional features and increase the resolution. Eventually, the researchers believe, the technology could be used for intelligent three-dimensional systems that can dynamically change their configuration, as well as for a new class of macroscale 3D printed objects that can deliver medicine or produce high resolution bone replacements.
“We believe this new approach will initiate the development of small molecule-based 3D printing materials and greatly accelerate the development of smart materials and devices beyond our current grasp that are capable of doing complex tasks in response to environmental stimuli,” the researchers stated.
The research was published in a paper entitled “Hierarchical Co-Assembly Enhanced Direct Ink Writing,” which you can access here. Authors include Longyu Li, Pengfei Zheng, Zhiyun Zhang, Qianming Lin, Yuyang Wu, Alexander Cheng, Yunxiao Lin, Christina M. Thompson, Ronald A. Smaldone, and Chenfeng Ke.
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