Abstract
Hydrophobizing of stretchable elastomer surfaces is considered and the reversible behavior of the resulting surface wetting state is examined after stretching and relaxing the hydrophobized samples. The environmental dust are analyzed in terms of elemental constitutes and size, and the dust pinning on the hydrophobized surface is measured. The dust removal mechanisms, by the water droplets on the hydrophobized surface, are investigated. We demonstrated that deposition of functionalized nano-size silica units on the elastomer surface gives rise to hydrophobicity with 135° ± 3° contact angle and low hysteresis of 3° ± 1°. Stretching hydrophobized elastomer surface by 50% (length) reduces the contact angle to 122° ± 3° and enhances the hysteresis to 6° ± 1°. However, relaxing the stretched sample causes exchanging surface wetting state reversibly. Water droplet rolling and sliding can clean the dusty hydrophobized surface almost 95% (mass ratio of the dust particles removed). Droplet puddling causes striations like structures along the droplet path and close examination of the few residues of the dust reveals that the droplet takes away considerably large amount of dust from surface.
Highlights
Surface cleaning from dusts remains important for sustaining the efficiency and output power of photovoltaic panels and concentrated solar troughs
The surface contact angle is measured as 135° ± 3° and contact angle hysteresis of 3° ± 1°
The water droplet contact angle increases to 132° ± 3° with the hysteresis of 5° ± 1°
Summary
Droplet behavior on soft hydrophobic surface is considered. Polyisoprene elastomer is incorporated in the experiments and the sample surfaces are hydrophobized. As the stretched sample is relaxed, it returns to original structure state and the closely agglomerated nano-size silica particles are observed (Fig. 1c). A small change in the roughness parameter results in almost 10° variation of the droplet contact angle on the sample surface. The droplet contact angle technique is adopted to measure the surface free energy of the dust in accordance with the early work[23,24] In this case, water, glycerol, and ethylene glycol are used in the measurements. The pinning force resulted because of the droplet adhesion under surface tension influence (Fad. γLV fD(cosθR cosθA), here, f corresponds to the texture solid fraction, D corresponds to the equivalent droplet diameter when it is spherical, θR represents the angle of receding, and θA is the angle of advancing.) causes sliding of droplet as it rolls. The droplet translational velocity along the hydrophobic surface is4: 2g[ΔLsinδ μf ΔL
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
