Effect of poly(dimethylsiloxane) binder in a silica-based superhydrophobic coating on mechanical properties, surface rou
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Research Letter
Effect of poly(dimethylsiloxane) binder in a silica-based superhydrophobic coating on mechanical properties, surface roughness, and wettability Divine Sebastian and Chun-Wei Yao
, Department of Mechanical Engineering, Lamar University, Beaumont, TX 77710, USA
Address all correspondence to Chun-Wei Yao at [email protected] (Received 11 June 2020; accepted 27 July 2020)
Abstract This work investigates the influence of poly(dimethylsiloxane) (PDMS) within a nanocomposite coating solution constituted by silica nanoparticles and toluene on mechanical properties, surface wettability, and surface morphology. The developed coating’s hardness and elastic modulus were studied in detail. A variation in mechanical properties was observed as the amount of PDMS was varied. Also, the average surface roughness, skewness, and kurtosis values show the influence of the amount of PDMS on the surface roughness characteristics of the coating. Furthermore, it was observed that the water contact angles were linked with the proportion of PDMS.
Introduction Superhydrophobic coatings have been a hot topic for the research community since the last few decades because superhydrophobicity has many applications, which include but are not limited to anticorrosion,[1,2] self-cleaning,[3] and antiicing.[4] Various methods exist for fabricating a superhydrophobic coating; these include the sol–gel method,[5] chemical vapor deposition,[6] physical vapor deposition,[7] and a nanocomposite solution.[8–12] Varied in their complexity, fabrication methods are selected according to which a basic substrate is to be coated and which chemicals are to be used. The basic requirements for developing a superhydrophobic coating are low surface free energy (surface chemistry)[13] and considerably higher surface roughness (surface morphology).[14] So, any fabrication technique, irrespective of its nature, includes distinct processing steps to alter these properties of surface chemistry and morphology to enhance superhydrophobic behavior. The one exception to this, out of the previously mentioned techniques, is the nanocomposite coating solution, as it can achieve the desired alterations in a single coating process.[15] Generally, a nanocomposite solution comprises nanoparticles such as silica or nanoparticles of varying sizes, a binder such as poly(dimethylsiloxane) (PDMS), and an appropriate solvent medium such as toluene or ethanol.[15] The nanoparticles are responsible for the required surface morphology. If they are functionalized prior to use to reduce surface free energy, they could also affect the required surface chemistry.[16] The role of the binder is to hold the constituents together, thereby achieving the desired mechanical properties rendering the coating durable.[17] One of the main problems associated with superhydrophobic coatings is their susceptibility to damage by external wear
and abrasion; this susceptibility is often caused by insufficient mechanical properties.[18] When it comes to nanocomposite coating solutions, since the bind
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