4D Printing Transforms Sulfur Waste into Soft Robots

A new printing technology transforms sulfur waste from the oil industry into smart shape-memory materials. The structures respond to external stimuli and can be fully reused.

A research team from South Korea has developed a 4D printing technology based on sulfur waste from petroleum refining. The method enables shape-changing structures that respond to heat, light, or magnetic fields and can be fully recycled after use.

The development comes from a joint team at the Korea Research Institute of Chemical Technology (KRICT), Hanyang University, and Sejong University. It is based on a polymer material with a high sulfur content that, despite previously difficult processing, can now be used for the first time in complex 3D-printed structures.

Material Reacts: 4D

To overcome the previously low flowability of sulfur-based plastics, the team developed a polymer network with looser chemical bonds. This allows the material to be extruded and processed into complex structures via 3D printing, according to the report.

Through precise control of the sulfur content and network structure, the researchers also achieved so-called shape-memory properties. As a result, printed structures can autonomously change their shape when exposed to heat or light—hence the term “4D.”

Additionally, components can be chemically welded together using a near-infrared laser within a few seconds. According to the researchers, if magnetic particles are mixed into the material, soft robots less than 1 cm in size can be created that move along external magnetic fields.

Closed-Loop Recycling

Another feature of the technology is a closed-loop material cycle. The printed structures can be melted down after use and reused as printing material.

The study results were published in the journal Advanced Materials.

This is a partly automated translation of this german article.