Enhanced dielectric, electromechanical and hydrophobic behaviors of core-shell AgNWs@SiO2/PDMS composites

Abstract This paper reports a feasible method to prepare polymeric nanocomposites with enhanced dielectric, electromechanical and hydrophobic performance by introducing the core-shell AgNWs@SiO 2 filler into polydimethylsiloxane (PDMS). The homogenous core-shell AgNWs@SiO 2 was firstly synthesized through a two-step sol-gel process. The thicknesses of AgNWs and SiO 2 coating layer are approximately 70 nm and 20 nm, respectively. The dielectric constant is improved effectively due to enhanced interfacial polarization, while extremely low dielectric loss and conductivity are achieved by introducing the insulating SiO 2 interlayer to moderate the internal surface area of core-shell nanowires and restrict the electron transfer between Ag nanowires. Typically, the PDMS nanocomposites with 20 wt% AgNWs@SiO 2 have a dielectric constant of 6.7, nearly 2.7 times larger than that of pure PDMS, and remains a quite low loss of 0.02 at 1 kHz. Meanwhile, nanocomposites also show improved electromechanical and hydrophoic properties. Nanocomposites with 10 wt% AgNWs@SiO 2 exhibit the highest electromechanical sensitivity ( β= 9.04), about 12.6 times higher than that of pure PDMS at 1 kHz. The static contact angle of nanocomposties with 20 wt% AgNWs@SiO 2 reaches 129°. All the improved performances show great potential application for dielectric elastomer material and electrowetting devices.