Microstructure-Controlled Polyacrylonitrile/Graphene Fibers over 1 Gigapascal Strength

Abstract

Controlling the microstructures in fibers, such as crystalline structures and microvoids, is a crucial challenge for the development of mechanically strong graphene fibers (GFs). To date, although GFs graphitized at high temperatures have exhibited high tensile strength, GFs still have limited the ultimate mechanical strength owing to the presence due to the structural defects, including the imperfect alignment of graphitic crystallites and the presence of microsized voids. In this study, we significantly enhanced the mechanical strength of GF by controlling microstructures of fibers. GF was hybridized by incorporating polyacrylonitrile (PAN) in the graphene oxide (GO) dope solution. In addition, we controlled the orientation of the inner structure by applying a tensile force at 800 °C. The results suggest that PAN can act as a binder for graphene sheets and can facilitate the rearrangement of the fiber’s microstructure. PAN was directionally carbonized between graphene sheets due to the catalytic effect of graphene. The resulting hybrid GFs successfully displayed a high strength of 1.10 GPa without undergoing graphitization at extremely high temperatures. We believe that controlling the alignment of nanoassembled structure is an efficient strategy for achieving the inherent performance characteristics of graphene at the level of multidimensional structures including films and fibers.

Ultrastrong Hybrid Fibers with Tunable Macromolecular Interfaces of Graphene Oxide and Carbon Nanotube for Multifunctional Applications

“…In addition, desirable structuring by solution processing enables the simple fabrication of strong assemblies. Many studies have been conducted from various perspectives on CNT‐ [ 25 , 26 , 27 , 28 , 29 , 30 , 31 ] and graphene‐based [ 32 , 33 , 34 , 35 , 36 , 37 ] hybrids and/or composite assemblies, and these studies have identified the superior properties and unique advantages of such hybrids. However, the reported mechanical properties tend not to surpass those of high‐performance carbon fibers (CFs).…”

Advances in Porous Graphene and Scalable Wet-Spinning Fiber Assembly

“…The electrical conductivity can be tuned by chemical doping and reduction of fibers during the wet-spinning stage of forming the porous structures. In another case, inspired by the defect control strategies used in traditional carbon fiber, the external force applied during the heat treatment process of wet-spinning PAN/GF can reduce the size and the alignment of pore defects inside the GF (Figure B) . As a result, the mechanical properties of the fibers, such as the tensile strength and Young’s modulus, are significantly improved.…”

“…(B) Schematic of carbonized PAN/GF at different applied tensions and comparison of the mechanical properties of hybridized GFs and the morphologies of carbonized PAN/GFs. Reproduced with permission from ref . Copyright 2021 American Chemical Society.…”

Graphene and CNT‐Based Smart Fiber‐Reinforced Composites: A Review

“…[10] In addition, the isolation of graphene in 2004 [11] has unveiled some novel 2D materials and their derivatives with excellent mechanical and multifunctional properties. [12][13][14][15][16] Such materials have shown great promise for use in structural composites applications due to their outstanding mechanical properties. [17][18][19][20][21] Furthermore, 2D materials can be produced in uniform dispersions via scalable, low-cost, and mass production methods [22] with great potential for applications in electronics, energy, membranes, coatings, and composites.…”