Researchers from Zhejiang University, Xi'an Jiaotong University and Monash University have developed a way to bind multiple strands of graphene oxide together, creating a process that could prove useful in manufacturing complex architectures.

Reversible fusion and fission of GO fibers imageReversible fusion and fission of GO fibers. Credit: Science

In recent years, materials scientists have been exploring the possibility of making products using total or partial self-assembly as a way to produce them faster or at less cost. In biological systems where two materials self-assemble into a third material, scientists describe this as a fusion process. Accordingly, when a single material spontaneously separates into two or more other materials, they refer to it as a fission process. In this new work, the researchers have developed a technique for creating graphene-oxide-based yarn that exploits both processes.

Rodolfo Cruz-Silva and Ana Laura Elías with Shinshu University and Binghamton University have published a Perspectives piece in the same issue of Science, outlining the work by the researchers and explaining why they believe the technique could prove useful in manufacturing efforts.

The work by the team is straightforward - they created multiple strands of graphene oxide and then dipped them in a solvent solution for 10 minutes. When the strands were pulled from the solution, they banded together forming a cord, or single strand of yarn. They also developed a means for reversing the process—dunking the strand of yarn in a different solvent solution.

The technique works because the graphene oxide strands swell when placed into the solution. That forces flakes that make up the outer layer of each of the fibers to pack together more densely, which results in a skin of sorts. As the bundle of strands is removed from the solution, the surface tension pulls the strands together into a cylindrical shape.

The newly created cord dries, allowing the fibers to bond. Then, putting the cord into the second solution relaxes the strands, breaking the bonds and releasing them back to their original form.