Wettability Property In Natural Systems: A Case of Flying Insects
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MRS Advances © 2018 Materials Research Society DOI: 10.1557/adv.2018.367
Wettability Property In Natural Systems: A Case of Flying Insects J. Sackey1,2,*, B.T. Sone1,4, K. A. Dompreh1,3, M. Maaza 1,2 1
Nanosciences African Network (NANOAFNET), iThemba LABS, Somerset West, Western Cape Province, South Africa.
2
University of South Africa (UNISA), Muckleneuk ridge, P.O. Box 392, Pretoria - South Africa,
3
Department of Physics, University of Cape Coast, Ghana
4
Physical Chemistry, Chemistry Department, University of the Free State, P.O. Box 339, Bloemfontein, Free State Province, South Africa
Abstract
Recently, scientists have demonstrated that material surfaces in nature that possess special wettability properties are composed of micro- and nanostructures. In this study, we focused on the importance of surface structures in determining the wettability of wings of the flying insect species: Idea malabarica, Lucilia sericata and Chrysomya marginalis. Scanning Electron Microscopy (SEM) analysis indicates the different nano-/micro- structures identified on the wings. Surface roughness which plays a role in influencing the wettability was theoretically estimated from the SEM images. While the spherical liquid water droplets used for testing wettability were observed to float on the surface of the Idea malabarica and Lucilia sericata wings, the surface of the Chrysomya marginalis wing was made completely wet. The super-hydrophobicity of the Idea malabarica wing as compared to the nearhydrophobicity/mild hydrophilicity of the Lucilia sericata wing and the distinct hydrophilicity of the Chrysomya marginilis wing could be attributed to its complicated composition of nano/microstructures and higher surface roughness value.
INTRODUCTION Super-hydrophobicity is a surface-morphology linked phenomenon recurrent in nature, one through which water striders float and move on water surface; lotus leaves are self-cleaning, and butterflies avoid sticking of their wings [1]. Recently, the surface morphologies of underwater creatures and plants have been widely investigated for their
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superhydrophobic properties [2-4]. Interest in these types of surface properties have grown over the past years due to the understanding of the criteria for forming such surfaces and the recognition of its potential. The superhydrophobic materials have found applications in anti-corrosive coatings, microfluidic devices, printing techniques, optical devices, etc. [5]. In many of these applications, the presence of an air layer trapped inside the rough surface can reduce liquid penetration. To characterize the hydrophobicity of a material surface, the contact angle (CA) as well as the contact angle hysteresis has to be considered [6]. The contact angle is the angle at which the liquid/vapor interface meets a given solid
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