Supplementary information Wet-spinning assembly of continuous, neat, and macroscopic graphene fibers Huai-Ping Cong, Xiao-Chen Ren, Ping Wang, Shu-Hong Yu* Division of Nanomaterials and Chemistry, Hefei National Laboratory for Physical Sciences at Microscale, Department of Chemistry, the National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230026, P. R. China Figure S1 | AFM image of the initial GO dispersion on mica wafer. (a) and the corresponding height profile (b). S1 Figure S2 | Wet-spinning set-up. Photograph of the wet-spinning set-up with a double-jet pump at a speed of 25 mL/min. Figure S3 | Flexibility of GO fibers. Photographs of (a) the spring-like GO fiber carried with a tweezers along the axial direction; (b) the knitted pattern of “USTC” in a cotton textile using a needle with the GO fibers as the threads. S2 Figure S4 | Tunable diameters of macroscopic GO fibers. (a) Photographs of GO fibers by the wet-spinning technique using nozzles with different sizes of 0.11, 0.26, 0.41, and 0.6 mm, respectively (from left to right). SEM images of GO fibers by spinning of GO dopes with different concentrations: (b) 5; (c) 8; (d) 10; (e) 22 mg/mL. Figure S5 | Microstructures of graphene fibers. SEM images with different magnifications of the graphene fiber prepared by chemical reduction of GO fiber. S3 D band G band Intensity (a) GO fiber (b) GO-PNIPAM fiber 2D band (c) Graphene fiber (d) Graphene-PNIPAM fiber 500 1000 1500 2000 2500 3000 3500 Wavenumber (cm-1) Figure S6 | Raman spectra of the single fiber. (a) GO. (b) GO/PNIPAM. (c) Graphene. (d) Graphene/PNIPAM. (b) (a) 120000 GO powder Counts / s Intensity (a.u.) 40 GO fiber 20 O1s (19.86 at.%) 80000 N1s (2.94 at.%) 40000 0 4000 as(-CH3) as(-CH2) 3000 s(-CH2) (C-N) 2000 Wavenumber (cm-1) C1s (77.20 at.%) (C-C) 1000 0 600 500 400 300 200 Binding Energy (eV) Figure S7 | Analyses of components of the GO fiber. (a) FT-IR spectra of GO powder and the single GO fiber. (b) XPS spectrum of the dry GO fibers. S4 Figure S8 | SEM images of the GO-epoxy resin composite fiber. (a) Outer surface of the fiber. (b) A broken fiber. (c) Different magnifications of the cross-section of the broken part in (b) marked with the white rectangle. (a) 600 (b) 100 Tensile Stress (MPa) Intensity (a.u.) 500 400 300 200 100 0 10 20 30 2(degree) 40 50 80 60 40 20 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Strain (%) Figure S9 | XRD pattern (a) and mechanic property (b) of the GO-epoxy resin composite fibers. S5 Figure S10 | SEM images. (a, b) GO/PNIPAM fiber by wet spinning GO/PNIPAM dope with the weight ratio of 1:1 and GO concentration of 5 mg/mL. (c, d) graphene/PNIPAM fiber prepared by chemical reduction of GO/PNIPAM fiber. (b) GO-PNIPAM fiber * as(-CH2) s(-CH2) Intensity * Amide I Amide II s(-CH3) * 1800 * (-NC) as(-CH3) (a) GO fiber (-COOH) (-CC) * * * (-C=O) (-COO-) 1600 1400 * (-CO) 1200 Wavenumber (cm-1) Figure S11 | FT-IR spectra. (a) A single GO fiber. (b) A single GO/PNIPAM fiber by wet spinning GO/PNIPAM composite dope with the weight ratio of 1:1. S6 Figure S12 | Structure and mechanic property of the GO-MWCNTs composite fibers. (a, b) SEM images of the outer surface and cross-section of GO-MWCNTs fibers with the weight ratio of GO and MWCNTs of 2:1. (c) Typical strain-stress curves of the single fibers with different weight ratios. S7