Strengthening and Stiffening Graphene Oxide Fiber with Trivalent Metal Ion Binders

Abstract

CommuniCation(1 of 6) 1600401 mechanical performance is limited compared to commercial carbon fibers. Here, we present a straightforward fabrication method to produce GO fibers with LC solution of GO using trivalent cation salts as an ionic binder. To utilize the full potential of GO fiber, it is critically important to control the microstructure of fiber. The microstructure of GO fibers, such as shape and d-spacing between sheets, is ultimately controlled by the metal cation coagulants which are then processed into a fiber. Given the advantages of LC-GO, the resulting microstructure dominates most of the fiber mechanical properties (stiffness, strength, strain, etc.), and consequently its control in the early stage is regarded as a key method to achieve high mechanical performance. The underlying advantage is that trivalent metal cations modulate chemical interactions between GO sheets and drive ion cross-linking, which improves mechanical properties remarkably.To see the effect of GO coagulation with multivalent cation binders, Co 2+ , Al 3+ , and Fe 3+ were considered. Well dispersed GO was prepared as described in the Experimental Section and was observed by atomic force microscopy (AFM) topography and the thickness of GO sheets were measured as 1.2 nm (Figure 1a). GO aqueous dispersions were prepared by dispersing GO powders in deionized water (DIW) by mild sonication (Figure 1b). Dispersed GO solutions (1.0 mg mL −1 ) were kept stationary between two crossed polarizers and their LC phases were characterized with the observation of the textures of nematic LC. As presented in Figure 1c, GO dispersion showed the optical birefringence morphology; dark and bright brushes were interwoven, signifying a nematic LC phase. This phase implies that the anisotropic particles are well dispersed within the dispersing media without aggregates, which is largely resulted from electrostatic repulsion. [1,[17][18][19] To observe the changes of LC-GO in the presence of cations, different metal salts were added at a concentration of 20 × 10 −3 m. The addition of cations eventually disrupted dense LC patterns. Interestingly, it was still possible to observe the birefringence effect. This observation indicates that the multivalent cation acts as an ionic binder for the GO and the dispersion formed stacked crystalline-like GO sheets.The prepared GO dispersions were spun and the dispersions gelated in the coagulation bath. The cations which diffuse into the inner structure of the GO gel undergo electrostatic attraction with the negative charge of GO's oxygen functional groups, leading to bonding in the basal planes. [20] Furthermore, the coordination bonds between the GO and metal cations act as bridges between the sheet edges. [21][22][23] The GO gels immobilized by cation binder are pulled out of the coagulation bath and continuously coiled along the reel. Drafting was not performed

Large-scale wet-spinning of highly electroconductive MXene fibers

“…Graphene-related fibers have gained considerable interest because of their versatile functionalities, such as lightweight, mechanical flexibility, bendability, stretchability, and the ability to be woven into textiles for the next generation of smart electronic gadgets 12,13 . In particular, to realize the macroscopic assembly of 2D nanosheets into fiber structures, the wet-spinning process, which utilizes the phase change ability of highly concentrated colloidal dispersions (i.e., \ in the liquid state) to transform into gel-fiber assemblies and solid fibers in a coagulation bath, has been demonstrated as a versatile pathway for the long and continuous mass production of fibers 11,14 . Notably, understanding the molecular interaction between sheets and systematic studies on the parameters of the coagulation process are crucial to achieving fiber formation from individual colloidal particles.…”

Dynamic assembly of liquid crystalline graphene oxide gel fibers for ion transport

“…S12). The tensile strength (301.4 MPa) of 4 v 1 -GO fibers was almost two times higher than that (152.3 MPa) of v 1 -GO fibers, indicating the defectless compact structure of 4 v 1 -GO fibers ( 21 ). The improved compactness of 4 v 1 -GO fibers was further confirmed with apparent density and porosity of both GO fibers, as summarized in table S4.…”

“…The disturbed core fluid became gradually coagulated with the distance from the nozzle due to the diffusion of ionic cross-linkers (Ca 2+ ) from the coagulation solution (fig. S3) ( 21 ). The most straightforward and well-supported explanation to this behavior is that the core fluid is subjected to a retardation, which causes the switch from alignment in the flow direction to alignment in the cross direction ( 22 ).…”

“…The nematic liquid crystalline nature of GO dispersion was examined using a POM, as reported elsewhere (fig. S1) ( 14 , 21 ).…”

Combination of Iron Chloride and Polyacrylamide as Coagulant-Flocculants to Remove Pollutants in Dye Wastewater

“…The addition of cationic charge enables neutralization of the solution by attaching onto the surface of negative charge particles to form micro floc particles [3]. Coagulant with trivalent ions are more efficient than those with divalent ions due to the amount of unoccupied charges [4]. Furthermore, the addition of flocculants (coagulant aids) contributes to an increased efficiency by promoting the destabilization of particles to form micro-floc [5].…”