Transformation of a Simple Plastic into a Superhydrophobic Surface

Abstract

Superhydrophobic surfaces are generally made by controlling the surface chemistry and surface roughness of various expensive materials, which are then applied by means of complex time-consuming processes. We describe a simple and inexpensive method for forming a superhydrophobic coating using polypropylene (a simple polymer) and a suitable selection of solvents and temperature to control the surface roughness. The resulting gel-like porous coating has a water contact angle of 160 degrees. The method can be applied to a variety of surfaces as long as the solvent mixture does not dissolve the underlying material.

Self-cleaning glazing products: A state-of-the-art review and future research pathways

“…Illustration of how self-cleaning glass works, in three steps, from left to right: 1) activation of the coating by UV radiation and natural dirtying, 2) decomposition of the organic dirt, and 3) rain water washes away the loosened and degraded dirt. Source: Pilkington Active [6] Several investigations have been carried out on hydrophilic and hydrophobic surfaces with their respective superhydrophilic and superhydrophobic counterparts or enhancements, and on self-cleaning properties and various possible application areas in general [1,2,5,10,11,12,22,24,25,27,33,34,35,36,37,38,39,40,41,42,43,44,45,46]. It is not within the scope of this work to go into details of all these, as the focus of this work is on self-cleaning characterization methods, state-of-the-art self-cleaning glazing products of today and future research pathways for self-cleaning glazing products of tomorrow.…”

“…The possibilities of the Lotus leaf with its hydrophobicity is investigated in several studies [25,34,35,45], and superhydrophobicity (including ultrahydrophobicity [42]) is furthermore the topic of yet several more studies [11,27,34,36,37,39,40,42,43,44,46], where links to nanostructure of the matter and hence nanotechnology are given in various works [1,12,33,35,40,45]. The large collection of water-repellent and self-cleaning plant surfaces with corresponding contact angles by Neinhuis and Barthlott (1997) [41] should be noted.…”

Superhydrophobic properties of ultrathin rf-sputtered Teflon films coated etched aluminum surfaces

“…Recently many methods have been developed to fabricate such superhydrophobic surfaces [5], [6], [7], [8], [9] and [10]. Erbil et al [5] described a simple and inexpensive method for forming a superhydrophobic coating using polypropylene and a suitable selection of solvents and temperatures to control the surface roughness.…”

Robust Cassie State of Wetting in Transparent Superhydrophobic Coatings

“…1−3 The Cassie state of wetting provides a large apparent water contact angle with low contact-angle hysteresis and results in a roll-off superhydrophobic surface, which is desired for practical applications such as self-cleaning windows and solar panels, 4−6 underwater drag reduction, 7,8 and anticorrosion coatings. 9 Various successful methods have been developed by mimicking well-known examples from nature (e.g., Lotus leaves and butterfly wings) to prepare artificial superhydrophobic surfaces with the Cassie state of wetting using lithographic methods, 10−12 sol−gel techniques, 4,9,13−15 phase separation in polymer blends, 16 electrospinning, 17,18 and others. 5,19−23 However, the Cassie state of wetting (roll-off) can easily and irreversibly transform to the Wenzel state of wetting (sticky) under external stimuli such as pressure, vibration, droplet impact, and droplet evaporation by complete filling of the air pockets with water.…”