Emulsion dipping based superhydrophobic, temperature tolerant, and multifunctional coatings for smart strain sensing applications

Abstract Superhydrophobic and electrically conductive coatings with multifunctionality have promising applications especially in the field of flexible electronics; however, developing the multi-functional coating with excellent durability, high temperature tolerance and corrosion resistance is still a challenge. Here, a novel emulsion dipping based strategy is, for the first time, proposed for preparation of the superhydrophobic smart coating. A substrate coated with the Ag precursor is dipped into an oil-in-water emulsion with the PDMS as the oil phase and aqueous reductant solution as the water phase while the curing agent of PDMS as the emulsifier. Ag precursor is reduced to Ag nanoparticles (AgNPs), while at the same time, the water evaporation produces the porous structure on the surface, and PDMS is served as both the interfacial adhesion agent and low surface energy agent. The obtained superhydrophobic and anti-corrosive AgNPs@PDMS coating possess a high electrically conductivity (up to 102 S/cm) and hence excellent Joule heating performance. The coating shows stable conductivity and superhydrophobicity after it experiences abrasion, bending, acid and ultrasonication treatment, performing outstanding stability and durability. Even exposed to a high temperature of 120 °C for 10 h, the AgNPs@PDMS coating can keep its water contact angle and conductivity unchanged, displaying a high temperature tolerance. The AgNPs@PDMS can also be coated onto the elastic polymer fabric and foam to fabricate strain and piezoresistive sensors with a large working strain range, high sensitivity, ignorable sensing hysteresis and excellent reusability.