underway to construct hydrogel materials into different shapes such as 3D, [5] 2D, [6] or fiber-like configurations, [7] wherein hydrogel fibers as a novel type of materials cast great impact on our daily life, ranging from smart textile, [8] conductor to functional reinforcements. [9] Compared with 3D and 2D hydrogels, fiber-like hydrogel, also known as 1D hydrogel fiber, always possess smaller cross-sectional areas, [10] which means such thin hydrogel fibers would bear more significant tensile force under the same load, leading to a higher standard on the mechanical properties for engineering 1D hydrogel fibers.With the synergistic effect of covalent and reversible bonds including hydrogen bonds, [11] hydrophobic interactions, [12] ionic bonds, and host-guest interactions, [13] a variety of hydrogel fibers with great mechanical properties have been developed, such as artificial spider silk with twisted core-sheath hydrogel fibers (tensile strength of 895 MPa and strain of 44.3%), [14] ultrastretchable fibers (tensile strength of 5.6 MPa and strain of 1180%), [9] and supramolecular fibers (tensile strength of 193 MPa and strain of 36%). [15] Despite their excellent mechanical properties, those hydrogel fibers are fabricated by manual drawing from the hydrogel, limiting their practical applications where scaled-up manufacture of fibers is required.To satisfy the demand of scaled-up production, the eligible hydrogel fibers are anticipated to be manufactured on a large scale via spinning process, including electrospinning, [16] extrusion spinning, [17] microfluidic or draw-spinning process. [18] For example, Ju et al. developed a hydrogel microfiber based on a continuous draw-spinning process, and the resulting fibers exhibited tensile stress of 1.4 MPa. [19] Song et al. spun a transparent hydrogel fiber possessing tensile stress of 200 kPa. [20] It should be noted that, as for spinning those hydrogel fibers, relatively low crosslinking density is often essential to a spinning solution due to the large deformation required during the spinning process and the requirements for spinning long and uniform hydrogel fibers, [19] which, in turn, leads to unsatisfied mechanical properties of the final spun hydrogel fibers.

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Rational and sustainable utilization of resources is critical for the continuous development of this society. Solar energy, as one of the renewables, shows great potential in replacing part of the traditional energy supplies since it is clean, abundant, and easily convertible to thermal, electrical, and biological energies. Using solar energy as the green driving force, interfacial solar evaporation is a promising way for clean water production to alleviate global water shortage, taking advantage of its high evaporation efficiency (more than 80%) and strong adaptability toward various water sources and fields. In recent years, various kinds of materials with diverse designs have been synthesized and applied in interfacial solar evaporation for clean water production. Herein, recent progress in interfacial solar evaporators for clean water production is systematically reviewed, based on the photothermal conversion mechanisms of solar absorbers, including carbonous, semiconductor‐based, and plasmatic ones. Furthermore, key design factors and strategies in interfacial solar evaporators are reviewed and discussed from material and structural design point of view, such as water transport, thermal management, latent heat for water vaporization, and salt accumulation. Finally, some perspectives related to resolving existing problems in the field are given.

The buckling phenomenon of sole zeolitic imidazolate framework-8 (ZIF-8) particles adsorbed at the water/oil interface was systematically studied. The droplet of ZIF-8 water dispersion was pended in oil for a certain time period and manually extracted to decrease the volume. With the reduction of interfacial area, the ZIF-8 particles were jammed together to form a wrinkling solid film at the water/oil interface, which could withstand the extraction of the droplet and be regenerated. The size and concentration of the particles affected the assembly kinetics. The rapidest assembly was observed for the medium-sized ZIF-8 particles (m-ZIF-8) among the three sizes tested (1.81 μm, 258 nm, and 51 nm). The droplet of 0.91 wt % m-ZIF-8 reached a nearly full surface coverage in 13 min, faster than those with the lower concentration of 0.46 or 0.28 wt %. The pH of the solution, ranging between 6 and 10.7, affected both the assembly kinetics and film stability. Cryo-scanning electron microscopy images of frozen m-ZIF-8-stabilized Picking emulsions showed a monolayer of ZIF-8 wetted by both oil and water phases. The observed buckling effect could be attributed to the stable adsorption of ZIF-8 at the water/oil interface and the interparticle interactions, related to the unique surface chemistry and polyhedral shape of the ZIF-8 crystals. This work provided some understanding on the interfacial property of ZIF-8 and the mechanism of sole ZIF-8-stabilized Pickering emulsions.

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