Fabrication of functional graphene fibers via structural modifications and their applications

Abstract

Graphene oxide has advantage to fabricate a multi-dimensional structure due to liquid crystallinity. Among them, graphene fibers which consist of aligned graphene structure have emerged as next-generation fibers due to their excellent mechanical and electrical properties. Research related to graphene fibers were mainly conducted about maximizing interactions between graphene sheets by reducing defects in the fibers to enhance mechanical and electrical properties. However, the low elongation and specific surface area induced by aligned graphene structure have difficulty in imparting various functions to the fiber. In this thesis, we present a method for fabricating functional graphene fibers through structural modification methods. First, helical graphene fibers with Archimedean spiral arrangement were fabricated through spontaneous rotation during drying. The morphological analysis of the helical structure was conducted through comparison of pitch and angle of helical structure depending on variables. Furthermore, solvent driven actuator and joule heating behaviors were investigated to analyze the effect of spontaneous helix formation on fibers. Next, porous graphene fibers with bumpy structure were fabricated through emulsion template method. The porous structure of fiber was controlled according to the droplet size and amount of the generated droplets in emulsion. The increased surface area and decreased weight per unit length by emulsion template have successfully led to supercapacitor application. It is expected that suggested methods to fabricate functional graphene fiber through structural modifications in this thesis could overcome the limitation of conventional graphene fibers and contribute to practical applications.