Self-propelled directional liquid transport (SDLT) has been observed on many natural substrates, serving as an efficient strategy to utilize surrounding liquids for a better habitat to the local environment. Drawing inspiration, various artificial materials capable of SDLT have been developed. However, the liquid transport velocity is normally very low (ca. 3−30 μm/s), which limits its practical applications. Herein, we developed novel pyramid-structured fibers with concave curved surfaces (P-concave curved-fiber, PCCF), which enable the ultrafast SDLT. Specifically, the liquid transport velocity can be up to ∼28.79 mm/s on a dry tri-PCCF, over 50 times faster than that on the surface of Sarracenia trichome (∼520 μm/s). The velocity is even faster on a wet fiber by two times (∼47.34 mm/s). Here, the Laplace pressure difference (F L ) induced by the tapered structure determines the liquid transport direction. It is proposed that both the capillary rises imparted by the concave curved surfaces and the oriented microridges/valleys and the enhanced F L aroused by the reduced crosssectional area accelerate the SDLT on surfaces of the PCCFs. Consequently, the PCCF takes a different liquid transport strategy with a convex-shaped advancing meniscus, differing from that on traditional conical fibers. Moreover, the as-developed PCCF is also applicable for underwater ultrafast SDLT of oil. We envision that the result will open a new perspective for fabricating a fibrous system for microfluidic and liquid manipulation.

Superwettable solid surfaces have attracted substantial research interest due to their outstanding performance. Various approaches have been developed for preparing superwettable surfaces via constructing a highly textured surface roughness and/or altering the surface free energy. Here, a facile dewetting strategy is proposed to produce multiple superwettabilities on copper hydroxide nanofiber arrays (Cu(OH) 2 -NFAs) by controlling the localized state of low-energy silicone oil. It is proposed that both the capillary forces along each nanofiber and the evaporation of the octane solvent contribute to the localization of the silicone oil in the NFAs. By varying the concentration of the silicone oil, its localized state changes from a scattered discontinuous distribution to a continuous thin/thick film, which leads to variations in the surface energy and surface roughness. Consequently, Cu(OH) 2 -NFAs with superhydrophilicity, superhydrophobicity with both high and low adhesion, and super slippery properties are prepared. Notably, a very small amount of silicone oil can alter the surface wettability of the Cu(OH) 2 -NFAs from superhydrophilic to superhydrophobic, which is attributable to the migration of silicone oil to the top of the nanofibers during the dewetting process. These results will provide new insights on the facile fabrication of functional surfaces with multiple superwettabilities.