Tuning Contact Line Dynamics on Slippery Silicone Oil Grafted Surfaces for Sessile Droplet Evaporation

Astrid Raynard, Anam Abbas*, Steven Armstrong, Gary Wells, Glen McHale, Khellil Sefiane, Dani Orejon Mantecon*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Controlling the dynamics of droplet evaporation is critical to numerous fundamental and industrial applications. The three main modes of evaporation so far reported on smooth surfaces are the constant contact radius (CCR), constant contact angle (CCA), and mixed mode. Previously reported methods for controlling droplet evaporation include chemical or physical modifications of the surfaces via surface coating. These often require complex multiple stage processing, which eventually enables similar droplet-surface interactions. By leveraging the change in the physicochemical properties of the outermost surface by different silicone oil grafting fabrication parameters, the evaporation dynamics and the duration of the different evaporation modes can be controlled. After grafting one layer of oil, the intrinsic hydrophilic silicon surface (contact angle (CA) ≈ 60°) is transformed into a hydrophobic surface (CA ≈ 108°) with low contact angle hysteresis (CAH). The CAH can be tuned between 1° and 20° depending on the fabrication parameters such as oil viscosity, volume, deposition method as well as the number of layers, which in turn control the duration of the different evaporation modes. In addition, the occurrence and strength of stick-slip behaviour during evaporation can be additionally controlled by the silicone oil grafting procedure adopted. These findings provide guidelines for controlling the droplet-surface interactions by either minimizing or maximising contact line initial pinning, stick-slip and/or constant contact angle modes of evaporation. We conclude that the simple and scalable silicone oil grafted coatings reported here provide similar functionalities to slippery liquid infused porous surfaces (SLIPSs), quasi-liquid surfaces (QLS), and/or slippery omniphobic covalently attached liquid (SOCAL) surfaces, by empowering pinning-free surfaces, and have great potential for use in self-cleaning surfaces or uniform particle deposition.

Original languageEnglish
Article number1750
JournalScientific Reports
Volume14
Issue number1
Early online date19 Jan 2024
DOIs
Publication statusE-pub ahead of print - 19 Jan 2024

Keywords / Materials (for Non-textual outputs)

  • Droplet evaporation
  • Contact line dynamics
  • Slippery oil grafted surfaces
  • Pinning/Depinning
  • Pinning suppression

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