Large-area, robust, transparent, and conductive ultrathin polymer nanocomposite membranes for flexible electronics

Ultrathin polymer nanocomposite membranes exhibit exceptional mechanical, electrical, and optical properties, making them increasingly important for flexible electronics and sensor devices. Here, we employ interfacial formation, assembly, and jamming of nanoparticle surfactants at liquid/liquid interfaces to fabricate large-area, robust, transparent, conductive, and freestanding ultrathin polymer nanocomposite membranes. Polystyrene (PS) dissolves in toluene and cellulose nanocrystal (CNC)-carbon nanotube (CNT) dispersed in water interact via electrostatic interactions and hydrogen bonding to form CNC-CNT surfactants rapidly at the oil/water interface. These surfactants assemble and jam to generate PS/CNC-CNT ultrathin nanocomposite membranes with exceptional mechanical properties. The freestanding membranes feature diameters up to 0.5 mm and are strong enough to support liquid masses at least 1000 times their own weight. We demonstrate that these ultrathin nanocomposite membranes exhibit tunable mechanical, electrical, and optical properties by simply varying the contents of PS and CNC-CNT, as well as the pH of the CNC-CNT aqueous dispersion, highlighting their great potential for applications in flexible electronics.