LAPONITE® sheets have been widely used for the preparation of tough nanocomposite hydrogels for enticing applications; however, their inferior dispersion in aqueous media resulting from electrostatic interactions between the nanosheets remarkably limits further improvements in the mechanical performances of the nanocomposite hydrogels. Here, we show a simple approach to dramatically accelerate the dispersion of LAPONITE® sheets in water, and in turn further improve the mechanical performances of the resulting nanocomposite hydrogels. Upon addition of poly(acrylic acid) (PAA), the electrostatic interactions between the LAPONITE® sheets were effectively reduced due to the adsorption of PAA onto the positively charged edges of the LAPONITE® sheets, thereby accelerating the dispersion of the LAPONITE® sheets in water. On this basis, a series of polyacrylamide (PAAm) hydrogels with a high content of LAPONITE® sheets was prepared, showing excellent tensile strength, stretchability, and anti-fatigue properties. This study will be beneficial for the preparation of LAPONITE®-based nanocomposite hydrogels bearing excellent mechanical properties for new applications.
This study utilized ionic liquids (ILs) to exfoliate Laponite nanosheets(XLP), altering the interlayer spacing of XLP, thus significantly improving its dispersibility and stability. More importantly, ILs can also benefit the dispersibility of graphene (GN) as well. The synergistic effects of sodium carboxymethyl cellulose (CMC), acrylamide, acrylic acid, SMA, and XLP significantly enhanced the mechanical properties of the hydrogel. At the same time, evenly dispersed GN enhanced the conductivity and sensing ability of the hydrogel dramatically. The hydrogel's multi-network structure, including physical cross-linking, chemical cross-linking, hydrophobic associations, and hydrogen bonding interactions, exhibited excellent mechanical performance and flexibility. The hydrogel sensors demonstrated excellent strain sensing capabilities, effectively responding under various strain conditions with high sensitivity and stability over a wide range of strains. Notably, the hydrogel sensors showed good responsiveness and repeatability in detecting human joint movements (wrist, elbow, knee), allowing for the differentiation of different joint motions. In summary, the P(AM-co-AA)/SMA/CMC/XLP/GN hydrogel, with its excellent dispersibility, mechanical properties, and sensing capabilities, exhibits great potential for applications in flexible sensors and wearable devices. This multi-mechanism enhancement strategy provides an effective method and theoretical foundation for designing high-performance hydrogel materials. Future research can further optimize the material's properties and expand its applications in other fields.
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