Superhydrophobic PDMS fabricated with a femtosecond pulsed laser for inhibiting icicle formation

Abstract

Snow and ice shed from highway structures can disrupt traffic, sometimes causing accidents. Anti-icing coating materials are used to prevent snow and ice from adhering to highway structures. However, most materials need to be repainted every few years. Here we examine water repellency at sub-zero temperatures and icicle formation for a superhydrophobic polydimethylsiloxane (PDMS) produced using femtosecond laser processing. When femtosecond laser pulses are irradiated onto stainless steel, a laser-induced periodic surface structure (LIPSS) is formed on the surface. When the structure is molded onto PDMS, the PDMS is found to exhibit super-hydrophobicity, with a water contact angle of 162.4±2.9° and a water sliding angle of about 3.0±0.8°. Experiments were conducted in which water droplets at 0.8±0.6 °C were continuously dropped onto a superhydrophobic PDMS surface at −11.9 °C±2 °C, forcing the formation of icicles. The water droplets were found to roll off the superhydrophobic PDMS immediately, which might inhibit the formation of ice and icicles. However, water droplets also froze on the superhydrophobic PDMS surface, indicating that a superhydrophobic surface with LIPSS inhibits the formation of ice but does not afford complete anti-icing.