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.

Superhydrophobic surfaces have suffered from being frequently penetrated by micro-/nano-droplets in high humidity, which severely deteriorates their water repellency. So far, various biological models for the high water repellency have been reported, which, however, focused mostly on the structural topology with less attention on the dimension character. Here, we revealed a common dimension character of the superhydrophobic fibrous structures of both Gerris legs and Argyroneta abdomens, featured as the conical topology and the micro-meter-scaled cylindrical diameter. In particular, it can be expressed by using a parameter of rp/l > 0.75 μm (r, l, and p are the radius, length, and apex spacing between fibers, respectively). Drawing inspiration, we developed a superhydrophobic micro-meter-scaled conical fiber array with a rather high rp/l value of 0.85 μm, which endows ultra-high water repellency even in high humidity. The micro-meter-scale asymmetric confined space between fibers enables generating a big difference in the Laplace pressure enough to propel the condensed dews away, while the tips help pin the air pocket underwater with a rather long life over 41 days. Taking advantage, we demonstrated a sustainable underwater aerobic reaction where oxygen was continuously supplied from the trapped air pocket by a gradually diffusing process. As a parameter describing both the dimension character and structural topology, the rp/l offers a new perspective for fabricating superhydrophobic fibrous materials with robust water repellency in high humidity, which inspires the innovative underwater devices with a robust anti-wetting performance.

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aligning NWs into micropatterns in order to achieve their advantages of integrated physicochemical properties and adequate device performance. [8] In this regard, various solution-coating techniques have been vigorously developed for their advantages in mild experimental conditions and large-scale production. So far, three categories of solution processes for aligning NWs have been reported based on the driving force: i) Anisotropic contraction of the solution film by the external forces, such as the technique of Langmuir-Blodgett; [9] ii) The shearing force technique where the NWs were aligned under the external shearing forces, including blown bubble film, [10] microfluidic approaches, [11] contact printing, [12] and solution shearing technique [13] ; and iii) Aligning NWs under applied external field, for example, the electric field of the dielectrophoresis approach. [14] However, these techniques suffer from limitations of either complicated equipment, sophisticated pretreated samples, difficulty in accurate controlling of the deposition region of the NWs, and the aggregation of NWs as well as the reorientation of the NWs in the postprocess. [15] Very recently, our group developed a facile directional liquid transfer approach guided by the Chinese brush to realize highly aligned Ag NWs through finely controlling the receding of the tri-phase contact line, [16] which is, however, not feasible for constructing multidimensional ordered micropatterns. So far, developing a facile and general approach to realize multidimensional, highly aligned micropatterned NWs has remained a challenge.In general, the essence of aligning NWs by solution coating is introducing directional force to compel NW ordering during the formation of NW film. As has been reported, carbon nanotube arrays (ACNTs) can be wetted by water gradually due to their surface texture and inherent hydrophilic nature. [17] As a result of water spreading and dewetting, fibrous coalescence of ACNTs occurs under strong capillary forces and Van der Waals interactions, by which ACNTs aggregated and bundled into micropatterns. [18] To be noticed, the anisotropic shrinking of the liquid film on the top of ACNTs happens in this process without any external energy input, which is an advantage for aligning NWs. Nanowire (NW) based micropatterns have attracted research interests for their applications in electric microdevices. Particularly, aligning NWsrepresents an important process due to the as-generated integrated physicochemical advantages. Here, a facile and general strategy is developed to align NWs using fibrous elastocapillary coalescence of carbon nanotube arrays (ACNTs), which enables constructing multidimensional ordered NW micropatterns in one step without any external energy input. It is proposed that the liquid film of NW solution is capable of shrinking unidirectionally on the top of ACNTs, driven by the dewetting-induced elastocapillary coalescence of the ACNTs. Consequently, the randomly distributed NWs individually rotate and move into dense alig...