By Josh Perry, Editor
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Researchers at the Korea Advanced Institute of Science and Technology (KAIST) in Daejeon, South Korea have demonstrated a new fabrication technique for producing graphene fibers that enhanced the mechanical and electrical properties of the material.

Cross-section SEM image of pure graphene fiber (left) and that of graphene fiber after two-stage defect control using polydopamine (middle and right). (KAIST)

According to a report from the institute, the graphene fibers, which have inherent defects and voids from the bending and wrinkling of oxide layers, were reinforced by the adhesion properties of dopamine, a polymer inspired by mussels.

“This functional polymer, which is studied in various fields, can increase the adhesion between the graphene layers and prevent structural defects,” the report explained. Thanks to the dopamine’s adhesion, researchers “succeeded in fabricating high-strength graphene liquid crystalline fibers with controlled structural defects.”

The team optimized the dopamine polymerization through high-temperature annealing and demonstrated that the nitrogen in dopamine molecules enhanced the electrical conductivity of the graphene fibers.

The research was recently published in Advanced Materials. The abstract stated:

“Inspired by mussel adhesive polydopamine (PDA), effective reinforcement of graphene?based liquid crystalline fibers to attain high mechanical and electrical properties simultaneously is presented.

“The two?step defect engineering, relying on bioinspired surface polymerization and subsequent solution infiltration of PDA, addresses the intrinsic limitation of graphene fibers arising from the folding and wrinkling of graphene layers during the fiber?spinning process. For a clear understanding of the mechanism of PDA?induced defect engineering, interfacial adhesion between graphene oxide sheets is straightforwardly analyzed by the atomic force microscopy pull?off test.

“Subsequently, PDA could be converted into an N?doped graphitic layer within the fiber structure by a mild thermal treatment such that mechanically strong fibers could be obtained without sacrificing electrical conductivity. Bioinspired graphene?based fiber holds great promise for a wide range of applications, including flexible electronics, multifunctional textiles, and wearable sensors.”