Double-network hydrogels with a gradient hydrophobic coating that prevents water evaporation and allows strong adhesion to a solid substrate
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All-weather solar-driven desalination systems, integrating photothermal evaporators with hybrid technologies, present a sustainable, cost-effective, and high-efficiency strategy for freshwater production. Despite significant advancements, previous reviews have predominantly focused on daytime evaporation, neglecting the broader scope of all-weather seawater evaporation. This review provides a comprehensive examination of the current status of all-weather seawater evaporators and their hybrid systems. Initially, the review details the system’s composition and operating principles, as well as the design criteria for high-performance evaporators. It then goes over various common photothermal conversion materials for seawater desalination, with a particular emphasis on those materials tailored for all-weather applications. It also offers an in-depth overview to the developed photothermal hybrid systems for all-weather seawater evaporation, including their working principles, the efficiency of evaporation across the day-night cycle, and their practical applications. Lastly, the existing challenges and potential research opportunities are thoroughly discussed.
Development of deformable and adhesive biocompatible polymer hydrogels by a simple one-pot method using ADIP as a cationic radical initiator
In this study, a highly viscoelastic, deformable, and adhesive hydrogel was synthesized by crosslinking a 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer hydrogel with a chemical crosslinker [N,N′-methylenebisacrylamide (MB)] using a cationic initiator, 2,2′-azobis-[2-(1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium-2-yl)]propane triflate (ADIP). The adhesive PMPC gel was tolerant to peeling during adhesion, and the adhesion energy of the hydrogel increased as the contact time with the adhesion target increased. Furthermore, the mechanism underlying the synthesis of deformable and adhesive hydrogels was determined by analyzing the polymerization behavior. The polymer synthesized with ADIP had a lower molecular weight than that synthesized with a conventional redox-type initiator, ammonium persulfate/N,N,N′,N′-tetramethylethylenediamine. Moreover, an analysis of the reactivity of various monomers and crosslinkers indicated low reactivity of the acrylamide-type crosslinker MB to methacrylate-type monomers; on this basis, the appropriate combination of monomers and crosslinkers for generating the target hydrogel was determined. The cytocompatibility of the prepared PMPC hydrogel was also confirmed. Thus, this study provides guidelines for the rational design of highly deformable, adhesive hydrogels with cytocompatibility.
Solar-driven interfacial evaporation technologies for food, energy and water
Solar-driven interfacial evaporation technologies use solar energy to heat materials that drive water evaporation. These technologies are versatile and do not require electricity, which enables their potential application across the food, energy and water nexus. In this Review, we assess the potential of solar-driven interfacial evaporation technologies in food, energy and clean-water production, in wastewater treatment, and in resource recovery. Interfacial evaporation technologies can produce up to 5.3 l m–2 h−1 of drinking water using sunlight as the energy source. Systems designed for food production in coastal regions desalinate water to irrigate crops or wash contaminated soils. Technologies are being developed to simultaneously produce both clean energy and water through interfacial evaporation and have reached up to 204 W m–2 for electricity and 2.5 l m–2 h–1 for water in separate systems. Other solar evaporation approaches or combinations of approaches could potentially use the full solar spectrum to generate multiple products (such as water, food, electricity, heating or cooling, and/or fuels). In the future, solar evaporation technologies could aid in food, energy and water provision in low-resource or rural settings that lack reliable access to these essentials, but the systems must first undergo rigorous, scaled-up field testing to understand their performance, stability and competitiveness.
Full recovery of brines at normal temperature with process-heat-supplied coupled air-carried evaporating separation (ACES) cycle
Conventional air-carried evaporating separation (ACES) technology, to achieve complete separation and recovery of water and salt in brine, tends to necessitate heating air above a critical temperature (typically>90 °C). In this paper, a novel concept of process-heat-supplied and an ACES cycle with this technique is proposed. A comprehensive thermodynamic analytical investigation is conducted. The results indicate that at heat source supply temperature Tsupply of only 45.17 °C, this novel unit is capable of achieving complete separation of water and salt from 5 wt% concentration brine. Meanwhile, thermodynamic mechanism analysis reveals that sufficient process-heat-supplied affords the fluid self-adaptive regulation on the driving potential of heat and mass transfer, thus circumventing traditional heat and mass transfer limitation. Additionally, a solar ACES system with process-heat-supplied incorporating heat pump is further proposed. For this system, theoretical evaporation rate for unit area of solar irradiation me-solar = 2.23 kg/(m2·h), integrated solar utilization efficiency ηi = 188%; while considering overall losses me-solar = 1.41 kg/(m2·h), ηi = 95.2%.
Stiff and self-healing hydrogels by polymer entanglements in co-planar nanoconfinement
Many biological tissues are mechanically strong and stiff but can still heal from damage. By contrast, synthetic hydrogels have not shown comparable combinations of properties, as current stiffening approaches inevitably suppress the required chain/bond dynamics for self-healing. Here we show a stiff and self-healing hydrogel with a modulus of 50 MPa and tensile strength up to 4.2 MPa by polymer entanglements in co-planar nanoconfinement. This is realized by polymerizing a highly concentrated monomer solution within a scaffold of fully delaminated synthetic hectorite nanosheets, shear oriented into a macroscopic monodomain. The resultant physical gels show self-healing efficiency up to 100% despite the high modulus, and high adhesion shear strength on a broad range of substrates. This nanoconfinement approach allows the incorporation of novel functionalities by embedding colloidal materials such as MXenes and can be generalized to other polymers and solvents to fabricate stiff and self-healing gels for soft robotics, additive manufacturing and biomedical applications.
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