Nacre Mimetic with Embedded Silver Nanowire for Resistive Heating

Nacre mimetics show great potential as lightweight, mechanically robust, and functional materials. Here, we introduce highly reinforced nacre-mimetic nanocomposite (NC), prepared via self-assembly of poly(vinyl alcohol) polymer-coated synthetic nanoclay from aqueous dispersions, as a transparent and mechanically robust substrate to prepare silver nanowire (AgNW) embedded thin-film resistive heater. AgNW is a promising substitute for widely used brittle and expensive indium tin oxide (ITO) due to its high electrical conductivity, excellent optical transparency, and good mechanical flexibility. However, current AgNW-based electrodes mostly suffer from limitations such as surface roughness and weak adhesion of AgNWs to flexible plastic substrates (e.g., poly(ethylene terephthalate), PET). We demonstrate that AgNW can be embedded in nacre-mimetic NC substrate by simple hot-pressing as compared to PET, leading to excellent stability against scotch tape peeling without any encapsulation layer. The AgNW/NC resistive heater shows uniform sheet resistance varying from 10 to 80 ω/sq with 70 to 91% transmittance at 550 nm on decreasing AgNW density from 111 to 23 mg/m². Moreover, AgNW/NC heater can generate rapid (10 s) and repetitive long-term heating response at low input voltages. It shows only small variation in temperature (4 °C) and sheet resistance during bending at 14 mm diameter for 2000 cycles as well as under various extreme mechanical deformations. Taking advantage of the conformability, mechanical deformability, and fast thermal response of the resistive heater, we demonstrated the in vitro temperature-triggered release of antibiotics (i.e.,vancomycin) from phase change material-coated, antibiotic-loaded hydrogels. Hence, we envision that the resistive heater can be introduced as a potential candidate into flexible electronics and wearable devices.