Poly(vinyl alcohol)/Laponite/Layered Double Hydroxide/Hydroxyapatite Nanocomposite Hydrogels for Stimulus-Responsive Devices

Nanocomposite hydrogels are supposed to combine the advantages of both a polymer matrix and filler. Without the use of organic additives, the incorporation of high-content inorganic nanofillers along with elevated properties remains a challenge. Accordingly, facilitated by the stepwise salting-out method, we proposed the PVA nanocomposite hydrogels containing multiple nanoscale minerals. Three kinds of nanominerals could reach certain electrostatic equilibrium, which helped to maintain their well-dispersed state even in the PVA matrix with high salinity. Unlike the traditional PVA nanocomposite hydrogels, whose mechanical properties tended to decrease upon the incorporation of inorganic fillers, the incorporation of multiple nanoscale minerals enhanced the mechanical properties including tensile strength and elongation at break. Besides, the unique multiple nanoscale mineral structure endowed our proposed nanocomposite hydrogels with high versatility, which could act as thermal insulators, flame-retardant matter, and respiration detectors. Instead of organic modification, this work innovatively utilizes intrinsic inorganic-to-inorganic interactions for achieving a fine nanocomposite microstructure in a polymer matrix. Our proposed nanocomposite hydrogels address potential applications for stimulus-responsive devices.