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Developing hydrogel actuators with excellent driving performance and extended lifespan remains challenging. Ti3C2Tx MXene, as a two-dimensional nanomaterial with a unique layered structure, has attracted widespread attention in flexible hydrogel actuators for its excellent optical absorption properties and tunable surface functionality. However, MXene faces difficulties in dispersion and is prone to oxidation, which significantly hinders the development and use of MXene-based hydrogel actuators. In this study, we fabricated a near-infrared light-driven hydrogel actuator with rapid photo responsiveness and antioxidative properties by incorporating modified MXene with antioxidant characteristics and the pore-forming agent polyvinyl alcohol into the poly(N-isopropylacrylamide) (PNIPAM) hydrogel system. We functionalized MXene nanosheets with (3-aminopropyl)triethoxysilane (APTES), effectively enhancing antioxidative properties, preventing structural degradation caused by spontaneous oxidation, and improving surface properties. This enhanced the dispersion stability of MXene in the system and extended its lifespan from 7 days to over two weeks. The hydrophilic polyvinyl alcohol chains served as drainage channels during hydrogel contraction, imparting the hydrogel with rapid driving capabilities (127.1° s−1). Additionally, leveraging the fast response characteristics, we designed an octopus-inspired light-driven soft swimmer and gripper. This work provides novel insights into the application of intelligent responsive hydrogels in biomimetic and practical scenarios. [ABSTRACT FROM AUTHOR]

Here, a supramolecular self-assembly hydrogel was designed for SnO-based anode through electrostatic interaction and ionic bonding between poly(allylamine hydrochloride) (PAH) chain and gelator phytic acid. Microrheology measurement was employed to investigate the self-sorting mechanism of the hierarchical nanostructured PAH. Results confirmed that ionically cross-link PAH improves the structural integrity of SnO nanospheres due to the reversible ionic bonding and thus increases the lifetime of the electrodes obviously. Besides, multi-walled carbon nanotubes (MWCNTs) were applied to improve the electrochemical performance of hollow SnO nanospheres due to their high conductivity. Results confirmed that the conductive network constructed by MWCNTs reduces the polarization of the composites while increases the specific capacity of the electrodes. Attributed to the synergistic effect of PAH-60 and MWCNTs, the composite electrodes show excellent electrochemical performance with a reversible capacity of 574 mAh g after 100 cycles at 100 mA g, a discharge capacity of 321 mAh g at 2000 mA g and a spring-back capacity of 506 mAh g at 200 mA g. Additionally, the prepared composite electrodes were observed to have a complete network structure after rate capability test, demonstrating a superior structural stability. [ABSTRACT FROM AUTHOR]

Conducting polymer hydrogels are emerging as a promising class of materials that combine the advantageous features of conventional hydrogels and organic conductors, and would potentially be used in many applications, especially for energy storage devices. To overcome the drawbacks of conventional synthesis, this work describes the use of amino trimethylene phosphonic acid as the gelator and dopant for rapidly fabricating hierarchical nanostructured polyaniline (PAni) hydrogel with excellent electronic conductivity and electrochemical properties. Owing to 3D porous nanostructures and high surface area, the PAni hydrogel exhibits potential as high-performance supercapacitor electrodes with specific capacitance over 420 F g. Furthermore, the rapidly formed PAni hydrogel was first used for 3D multilayer printing of micro-patterns due to the unique synthesis method and desirable processability. Taken together, these results suggest that the PAni hydrogel networks exhibit highly useful for a broad range of applications. [ABSTRACT FROM AUTHOR]

Uniform dispersion of two-dimensional (2D) graphene materials in polymer matrices remains challenging. In this work, a novel layer-by-layer assembly strategy was developed to prepare a sophisticated nanostructure with highly dispersed 2D graphene oxide in a three-dimensional matrix consisting of one-dimensional bacterial cellulose (BC) nanofibers. This method is a breakthrough, with respect to the conventional static culture method for BC that involves multiple in situ layer-by-layer assembly steps at the interface between previously grown BC and the culture medium. In the as-prepared BC/GO nanocomposites, the GO nanosheets are mechanically bundled and chemically bonded with BC nanofibers via hydrogen bonding, forming an intriguing nanostructure. The sophisticated nanostructure of the BC/GO leads to greatly enhanced mechanical properties compared to those of bare BC. This strategy is versatile, facile, scalable, and can be promising for the development of high-performance BC-based nanocomposite hydrogels. [ABSTRACT FROM AUTHOR]