Figure a shows a graphene fiber with a wrinkled circular cross-section where spontaneous flattening does not occur, and Figure b shows a flattened graphene fiber due to spontaneous flattening.
[Asia Economy Reporter Junho Hwang] A technology to cheaply and easily process graphene, known as the material of dreams, into carbon fiber has been developed in Korea. Compared to conventional fibers, the mechanical strength is more than three times higher and electrical conductivity is improved by about 1.5 times, enabling the production of carbon fibers that are expected to be used in wearable device components and mask purification filters.
The research team led by Professor Sangwook Kim of the Department of Materials Science and Engineering at the Korea Advanced Institute of Science and Technology (KAIST) announced on the 13th that they developed a technology to produce graphene fibers through an easy solution process using inexpensive graphite used in pencil leads, and their related research paper was published in the international academic journal ACS Central Science.
Development of Graphene Fibers with Flat Cross-Section
Schematic diagram of the fabrication process of flat graphene fibers produced through the spontaneous flattening phenomenon of two-dimensional materials
The research team discovered for the first time in the world that fibers made of 100% graphene spontaneously become flat during the manufacturing process, resulting in a belt-like cross-section. They induced hydration by adding a small amount of water to graphene oxide dispersed in an organic solvent. Through this, the graphene oxide in the solution spread without wrinkles, exhibiting a thermodynamically stable liquid crystal phase, and further found that the structure of graphene oxide spontaneously transformed into a flat belt shape.
The team emphasized the significance of clarifying that while conventional fibers typically have a circular cross-section, fibers made of graphene, a flat two-dimensional material at the atomic level, have a stable structure with a flat cross-section.
Applications in Wearables, Mask Purification Filters, and More
The newly developed flat belt-shaped graphene fibers have excellent internal stacking alignment of graphene, significantly enhancing the mechanical strength and electrical conductivity of the fibers. Compared to conventional fibers with circular cross-sections, the mechanical strength improved by about 3.2 times (320%) and electrical conductivity by about 1.5 times (152%).
In particular, these fibers can be made into flexible fibers that bend very easily along the flat surface direction, making them useful for flexible devices and wearable components.
Professor Sangwook Kim, the lead researcher, explained, "When fibers are made from two-dimensional materials like graphene, a flat belt shape is the ideal arrangement structure. Flat graphene fibers have flexible properties along the flat surface direction, which can solve the problem of conventional carbon fibers that break easily, and they can also be usefully applied as filter materials for masks, which is a recent issue."
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