Abstract: Structurally well-defined graphene nanoribbons (GNRs) have attracted great interest because of their unique optical, electronic, and magnetic properties. However, strong π-π interactions within GNRs result in poor liquid-phase dispersibility, which impedes further investigation of these materials in numerous research areas, including supramolecular self-assembly. Recently, Mai's group has synthesized a type of "rod-coil" brush-like macromolecules consisting of structurally defined GNRs grafted with hydrophilic poly(ethylene oxide) (PEO) chains (denoted as GNR-PEO). The PEO grafting affords the GNRs with excellent dispersibility in water with high GNRs mass concentration of up to 0.5 mg/mL. More interestingly, GNR-PEO exhibits 1D hierarchical self-assembly behavior in aqueous phase, leading to the formation of ultralong nanobelts, or spring-like helices, with tunable mean diameters and pitches. Moreover, the superstructures in aqueous dispersions are absorbed in the near-infrared range, which enable highly efficient conversion of photon energy into thermal energy. Mai's study not only opens avenues for fundamental study of GNRs self-assembly, but also affords opportunities to extend GNRs research to a wide range of aqueous-based fields, such as photothermal tumor therapy.