Search

Although diverse uranium (U) adsorbents have been explored, it is still a great challenge for high-efficient uranium extraction form seawater. Herein a wood-mimetic oriented porous Ti3C2Tx-MXene/gelatin hydrogel (MGH) has been explored through growing directional ice crystals cooled by liquid nitrogen and subsequently forming pores by freeze-dry (Ice-template) method, for ultrafast and high-efficient U-adsorption from seawater with great enhancement by both electric field and sunlight. Different from disperse Ti3C2Tx-MXene powder, this MGH not only can be easily utilized but also can own ultrahigh specific surface area for high-efficient U-adsorption. The U-adsorbing capacity of this MGH (10 mg) can reach 4.17 mg·g−1 after only 1 week in 100 kg of seawater, which is outstanding in existing adsorbents. Furthermore, on the positive pole of 0.4 V direct current source or under 1-sun irradiation, the U-adsorbing capacity of the MGH can increase by 57.11% and 13.57%, respectively. Most importantly, the U-adsorption of this hydrogel can be greatly enhanced by simultaneously using the above two methods, which can increase the U-adsorbing capacity by 79.95% reaching 7.51 mg·g−1. This work provides a new biomimetic porous MXene-based hydrogel for electric field/sunlight bi-enhanced high-efficient U-extraction from seawater, which will inspire new strategy to design novel U-adsorbents and systems.

Stimuli-responsive color-changing and shape-changing hydrogels are promising intelligent materials for visual detections and bio-inspired actuations, respectively. However, it is still an early stage to integrate the color-changing performance and shape-changing performance together to provide bi-functional synergistic biomimetic devices, which are difficult to design but will greatly expand further applications of intelligent hydrogels. Herein, we present an anisotropic bi-layer hydrogel by combining a pH-responsive rhodamine-B (RhB)-functionalized fluorescent hydrogel layer and a photothermal-responsive shape-changing melanin-added poly (N-isopropylacrylamide) (PNIPAM) hydrogel layer with fluorescent color-changing and shape-changing bi-functional synergy. This bi-layer hydrogel can obtain fast and complex actuations under irradiation with 808 nm near-infrared (NIR) light due to both the melanin-composited PNIPAM hydrogel with high efficiency of photothermal conversion and the anisotropic structure of this bi-hydrogel. Furthermore, the RhB-functionalized fluorescent hydrogel layer can provide rapid pH-responsive fluorescent color change, which can be integrated with NIR-responsive shape change to achieve bi-functional synergy. As a result, this bi-layer hydrogel can be designed using various biomimetic devices, which can show the actuating process in the dark for real-time tracking and even mimetic starfish to synchronously change both the color and shape. This work provides a new bi-layer hydrogel biomimetic actuator with color-changing and shape-changing bi-functional synergy, which will inspire new strategies for other intelligent composite materials and high-level biomimetic devices. [ABSTRACT FROM AUTHOR]

[Display omitted] • A morph-genetic biomimetic concept for fabricating zwitterionic hydrogels was proposed. • Macro-porous structures inside CTDPH matrix avoid the formation of salt crystallization. • The seawater evaporating rate of CTDPH increases to 3.11 kg m-2h−1 under 1-sun irradiation. • The CTDPH maintains 91.6% of its original solar evaporation rate even after 10 cycles. Huge seawater resources are of utmost importance in addressing the increasing and severe water shortage worldwide. However, high-efficiently and sustainably extracting fresh water from seawater through solar evaporation remains a challenging task. Herein, we propose a novel approach based on the morph-genetic biomimetic concept, utilizing a cuttlebone-templated directional porous hydrogel (CTDPH). By etching away the cuttlebone (CaCO 3) in the hydrogel network, we have developed a zwitterionic material that exhibits high-efficiency photo-thermal conversion, resistance to salt deposition, and super hydrophilicity, enabling high-efficiency solar evaporation. The resultant CTDPH demonstrates a high level of photo-thermal conversion efficiency, thanks to the incorporation of MXene (Ti 3 C 2 T x) 2D nanosheets. By introducing polyzwitterions into the hydrogel matrix, the CTDPH achieves superhydrophilicity, greatly enhancing the transport of seawater. More importantly, the CTDPH possesses a penetrating oriented macro-porous structure, enabling rapid seawater transportation while effectively preventing salt crystallization. This prevents salt deposition on the surface of the hydrogel even during continuous 12-hour 1.0 sun irradiation. As a result, compared with the MXene-free gels and cuttlebone-reserved gels, this CTDPH can largely increase the seawater evaporating rate from 0.73 or 1.75 to 3.11 kg m-2h−1 under 1.0 sun irradiation. Furthermore, even after undergoing 10 cycles of seawater evaporation, the CTDPH still maintains 91.6% of its original solar evaporation rate (2.85 kg m-2h−1). The CTDPH emerges as a promising contender, offering both high efficiency and sustainability for solar evaporation from seawater, while simultaneously paving the way for innovative approaches to explore other materials and systems in the realm of solar evaporation. [ABSTRACT FROM AUTHOR]

• PPy-coated P(NIPAM-ABP) electrospun nanofiber can provide high strength. • PPy-coating by in situ polymerization can provide high light-responsive. • The actuator owns ultrafast deformation and rapid recovery. • The actuator can realize various 3D programmable complex deformations. • We have explored new biomimetic devices based on the advantages of the actuator. Intelligent hydrogels are promising for biomimetic actuators, but acquiring actuations with both high speed and powerful force is still extremely difficult. Herein, a new robust polypyrrole (PPy)-coated copoly(isopropylacrylamide-4-benzoylphenyl acrylate) [P(NIPAM-ABP)] electrospun light-responsive hydrogel is explored. The (PPy)-coated P(NIPAM-ABP) hydrogel can be obtained via in-situ polymerization of pyrroles on the nanofiber-oriented electrospun P(NIPAM-ABP) hydrogel. Compared with original P(NIPAM-ABP) hydrogel, this PPy-coated P(NIPAM-ABP) hydrogel can integrate highly-enhanced mechanical strength (from 1.21 to 5.12 MPa of tensile strength) and ultrahigh-efficiency of photothermal conversion together. In addition, the orientation of P(NIPAM-ABP) nanofibers can still maintain well for programmable complex deformations. Consequently, the as-prepared robust bi-hydrogel actuator with ultrafast and complex deformations has been achieved, through bonding the PPy-P(NIPAM-ABP) hydrogel membrane with a polyethylene glycol diacrylate-cellulose nanofiber (PEGDA-CNF) composite hydrogel membrane via interfacial ultraviolet (UV) polymerization of PEGDA monomers. Several light-responsive biomimetic actuating devices have been achieved, which owning powerful force (can grab up 100 times of self-weight), rapid speed (1285.71°/s of folding) or precisely programmable complex deformations. Furthermore, two biomimetic devices with synergistic functions of the three advantages above have been explored, which can mimic the child's sit-up and the starfish's continuous crawling movement respectively. This work provides a robust remotely-controlled light-responsive hydrogel actuator with powerful force, ultrafast speed and programmable complex actuations, which will inspire the design and fabrication of novel soft biomimetic actuating materials and systems. [ABSTRACT FROM AUTHOR]