Efficient fabrication of lightweight polyethylene foam with robust and durable superhydrophobicity for self-cleaning and anti-icing applications

The poor robustness and durability of superhydrophobic surfaces under various externally imposed stresses have become a challenging issue for practical applications. Here, an efficient dissolution and modification strategy is proposed for facilely fabricating superhydrophobic polyethylene (F-PE/SiO2) foam with 98.6% porosity using sodium chloride (NaCl) as a sacrificial template and superhydrophobic nano-silica particles as a surface chemical modifier. A microscale porous and interconnected 3D framework is formed when NaCl is dissolved and the nano-silica particles adsorb on the surface of interconnected pores to form nanoscale structures. The F-PE/SiO2 foam exhibits a water contact angle (CA) of 158 ± 2° and a sliding angle (SA) of 4 ± 2°. Interestingly, the F-PE/SiO2 foam could maintain its superhydrophobicity under 980 Pa pressure of water droplet impacting and 8.1 kPa pressure of water flow impacting. Besides robust dynamic superhydrophobicity, the F-PE/SiO2 foam exhibits exceptional mechanical durability against knife scratching, tape-peeling, bending-twisting, and ultrasonication in ethanol because of unique hierarchical micro-nanostructure and the stably adsorbed nano-silica particles. Impressively, the F-PE/SiO2 foam maintains superhydrophobicity upon abrasion damage until all the thickness is worn away, which are potentially advantageous in practical applications. Moreover, this F-PE/SiO2 foam also demonstrated excellence in anti-wetting, self-cleaning and anti-icing, which makes the product can effectively reduce the damage caused by surface pollution, ice formation, and other natural factors when applied to oil-water separation and insulation material of refrigerator.