Fig. 1. In situ observation of dynamic self-assembly of GO gel fibers.

(A) Schematic of the experimental set-up: The assembly apparatus was installed on the stage of a POM, and the assembly process was recorded with a high-speed camera focused on the glass nozzle tip. The final GO hydrogel fibers can be reeled on a bobbin as shown in the photo. (B) Schematic illustration showing flow-driven alignment of GO sheets and formation of hydrogel fiber. (C and D) POM snapshots capturing different assembly behaviors of GO gel fibers (C) without and (D) with the addition of NH₄OH in the CaCl₂ coagulation solution. Snapshots were taken at various rates of the take-up roller (v₂). Note that the crossed polarizers were rotated 45° from the fiber axis. (E and F) POM images showing degree of alignment in GO gel fibers obtained at (E) 3v₁ in the CaCl₂-only coagulation solution and (F) 4v₁ in the NH₄OH and CaCl₂ coagulation solution.