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Open AccessFeature PaperArticle

Superspreading on Hydrophobic Substrates: Effect of Glycerol Additive

School of Chemical Engineering, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Colloids Interfaces 2019, 3(2), 51; https://doi.org/10.3390/colloids3020051
Received: 15 April 2019 / Revised: 16 May 2019 / Accepted: 29 May 2019 / Published: 31 May 2019
(This article belongs to the Special Issue Wetting on Micro/Nano-Scale: From Fundamentals to Application)
The spreading of solutions of three trisiloxane surfactants on two hydrophobic substrates, polyethylene and polyvinylidenefluoride, was studied with the addition of 0–40 mass % of glycerol. It was found that all the surfactant solutions spread faster than silicone oil of the same viscosity, confirming the existence of a mechanism which accelerates the spreading of the surfactant solutions. For the non-superspreading surfactant, BT-233, addition of glycerol improved the spreading performance on polyvinylidenefluoride and resulted in a transition from partial to complete wetting on polyethylene. The fastest spreading was observed for BT-233 at a concentration of 2.5 g/L, independent of glycerol content. For the superspreading surfactants, BT-240 and BT-278, the concentration at which the fastest spreading occurs systematically increased with concentration of glycerol on both substrates from 1.25 g/L for solutions in water to 10 g/L for solutions in 40% glycerol/water mixture. Thus, the surfactant equilibration rate (and therefore formation of surface tension gradients) and Marangoni flow are important components of a superspreading mechanism. De-wetting of the solutions containing glycerol, once spread on the substrates, resulted in the formation of circular drop patterns. This is in contrast to the solely aqueous solutions where the spread film shrank due to evaporation, without any visible traces being left behind. View Full-Text
Keywords: spreading kinetics; trisiloxane surfactants; Marangoni effect; dynamic surface tension; diffusion coefficient; viscosity spreading kinetics; trisiloxane surfactants; Marangoni effect; dynamic surface tension; diffusion coefficient; viscosity
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MDPI and ACS Style

Kovalchuk, N.M.; Dunn, J.; Davies, J.; Simmons, M.J.H. Superspreading on Hydrophobic Substrates: Effect of Glycerol Additive. Colloids Interfaces 2019, 3, 51.

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