The Preparation And Properties Of Colored Reduced Graphene Oxide Fibers

Two-dimensional nano-carbon material,graphene,has attracted many researchers due to its excellent electrical and mechanical properties,high thermal conductivity,and stable chemical properties.In order to integrate the performance of graphene into macroscopic materials,macroscopic one-dimensional fiber materials,two-dimensional film materials,and three-dimensional gel materials are assembled in graphene as a unit.One of the potential applications of one-dimensional materials in wearable textiles and supercapacitors has attracted the attention of scientists.However,there are still many problems in the application of graphene-based fibers in textiles.Firstly,the existing graphene-based fibers are basically bare,and are easily in contact with each other in the criss-cross texture of the textiles.Furthermore,the fibers are dark black due to the presence of graphene,which also limits their application on colorful textiles.In order to solve these problems,a colored insulating shell structure is prepared on the surface of the graphene based fiber or the polyester/graphene fiber by the dipping method or the coaxial spinning method,which not only solves the short-circuit problem but also provides the color to graphene fibers,expanding its application on wearable textiles.The graphene oxide?GO?dispersion was prepared by using concentrated sulfuric acid,phosphoric acid,potassium permanganate and graphit flakes as raw materials.The prepared graphene oxide sheet size distribution was within 6-110?m,with an average size of 39?m.It was a large layer of graphene oxide with thickness of 1.08 nm.The viscosity of the graphene oxide dispersion decreases with increasing shear rate,which is a typical non-Newtonian fluid.Graphene oxide dispersion had a nematic liquid crystal state at a concentration of 2 mg/m L,and the nematic phase area gradually increased with an increase in the concentration.The liquid crystal state has been completely formed at 10 mg/m L,and the liquid crystal state is more pronounced with more concentration.Graphene oxide fibers were prepared by wet spinning,and graphene?rGO?fibers were obtained after chemical reduction.Then,the titanium dioxide layer was coated by impregnation to cover the graphene fibers.When the content of titanium dioxide reaches 15%and polyurethane?PU?content is 5%,the titanium dioxide?TiO₂?coating has a good hiding and adhesion property.Finally,the pigment/PU layer was coated to obtain colored graphene fibers.The gel-GO fibers was observed with a polarizing microscope and a bright steak structure was found inside the fibers.As the fibers dried,the fibers gradually became thinner,but the inner steak structure was consistent.With the increase in the number of immersed titanium dioxide,the grooves on the surface of the graphene fibers were gradually filled.After coating eight times,the graphene fibers were completely covered,and the fibers exhibited a circular cross-section and a dense structure.The fiber surface was smooth.After 2 additional coating of the red pigment/PU layer,the fibers appeared bright red.The atomic ratio of carbon to oxygen detected by XPS was increased from 4.23 to 6.44,and the ratio of fiber I_D/I_G after reduction was increased from 0.84 to 1.03,indicating that the fiber surface contains oxygen was removed.After the coating of the fiber,the conductivity of the inner layer of the graphene fiber is basically unchanged,and the conductivity is 156 S/cm.The conductivity did not change substantially with the bending angle and the bending numbers.After the graphene oxide fibers sequentially reduced and coated,the tensile strength of the fibers was significantly increased from 43 MPa to 453 MPa,and raised to 531 MPa,respectively.The fiber color was characterized by visible light reflectance.It was found that after the fiber was coated with titanium dioxide and a pigment coating,the color changed from dark black to white and finally to red,and the color remained stable in strong acid and strong alkali solution.Colored graphene fibers with a core-shell structure can be prepared by impregnating TiO₂and a pigment coating on the rGO fibers,but the operation process is complicated and not conducive to fibers stability.The colored chitosan/GO fiber was prepared by coaxial wet spinning with a mixture of pigment and chitosan solution as the outer spinning solution and graphene oxide as the inner spinning solution,respectively.After chemical reduction,colored chitosan/rGO fibers were obtained.By comparison of the reduction of gel state?wet reduction?and reduction of dry state?dry reduction?,the mechanical and electrical properties of the fibers were investigated and it was found that the electrical conductivity of the fibers obtained by the wet reduction was 1-2 times higher than that of the dry reducing fibers.On the order of magnitude,it has a conductivity of 70 S/cm with excellent bending durability,and tensile strength is also slightly increased to 98 MPa.The analysis of the micro-morphology of the fibers shows that before and after the reduction of the fibers,the shell becomes slightly rougher,but the shell can still cover the graphene fibers.The infrared and Raman spectra were used to analyze the degree of reduction of the inner fiber.It was found that the original hydroxyl,carboxyl,and epoxy groups of GO were reduced or disappeared after reduction.The I_D/I_G ratio increased from 0.65 to 0.79,and reduction of the inner fiber was effective.The color of the fiber does not change substantially before and after the reduction,and the fiber can be shuttled up and down into the fabric with weavability.Although graphene-based fibers can be woven into fabrics,the spinnability cannot be compared with conventional fibers.Therefore,polyester fibers were used as the substrate,and impregnated with graphene oxide.The titanium dioxide was coated to cover the black color,and the pigment/PU layer was finally provided.After the white polyester fiber was impregnated with GO and reduced,a graphene blocky region is formed on the surface and becomes dark black.Infrared and Raman spectroscopy characterization of the fiber show that the peaks of hydroxyl,carboxyl,and epoxy groups decreased or disappeared after the reduction,and I_D/I_G value increased from 0.62 to 0.68,the fiber was effectively reduced.With the increase of the number of impregnated GO,the conductivity of the fiber increases significantly.After the 4times of impregnation,the conductivity of the fiber was saturated and the bending stability was good.After the polyester/graphene fiber was coated with the red pigment layer,the reflectant rate in the red light wavelength region reaches 50%.Fibers can be woven in fabrics to enhance the functionality.