Highly Bendable Graphene Liquid Crystalline Fiber via Molecular Level Lubrication of 0D Nanodiamond

Graphene fiber, composed of 2-dimensional graphene sheets, is one of the new class of carbon-based fiber with distinctive material properties particularly useful for electro-conductive components for wearable devices.Nowadays, flexible graphene fibers are principally employing soft dielectric additives, such as polymers, which can significantly deteriorate the genuine electrical properties of pristine graphene-based structures. In this research, molecular level lubricating 0-dimensional nanodiamond as an effective physical property modifier is introduced to improve the mechanical flexibility of graphene fibers by relieving the tight interlayer stacking among 2-dimensioanl graphene sheets. Nanoscale sized nanodiamond effectively increases tensile strain and bending strain of graphene/nanodiamond composite fibers, while maintaining the genuine electrical conductivity of pristine graphene-based fiber. The molecular level lubricating mechanism is elucidated by friction force microscopy in nanoscale via atomic force microscopy as well as by shear stress measurement in macroscopic scale. Resultant highly bendable graphene/nanodiamond composite fiber is successfully weaved into all graphene fiber-based textiles and wearable Joule-heaters, proposing the potential for reliable wearable applications.