Microwave-assisted deposition, scalable coating, and wetting behavior of silver nanowire layers

Abstract

Silver nanowires with various aspect ratios were synthesized at 160°C within 20 to 60min and were coated onto glass substrates, using a microwave-assisted (MA) approach followed by spin coating treatment. As-grown Ag nanowires exhibit a face-centered cubic crystal structure, and their heights can be well controlled by different microwave periods. The fluorination coating can induce super water and oil repellencies of Ag wires, i.e., the maximal values of contact angle are 153.8° (water) and 146.2° (ethylene glycol, EG). These water repellencies can be attributed to an air layer being confined to the nanowires, thus, leading to water droplets sitting on the Ag surfaces, referred to as the Cassie state. When the Young–Duprè equation incorporated with the Cassie parameter is taken into account, the lowest work of adhesion (Wad) values of the Ag films for water and EG repellencies are found to be 7.4 and 7.6mJ/m2, respectively. The decreasing functions of the surface fraction and the Wad value with the height reveal that the Ag nanowires offer an air cushion to repel the drop penetration, thereby inducing the low work required for the movement of droplets on the resulting silver surface. Accordingly, this study offers fundamentals on the liquid repellency of Ag nanowire surfaces fabricated by an efficient MA synthesis at low temperature.