Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 43: Wetting, Fluidics and Liquids at Interfaces and Surfaces (joint session CPP/DY)

CPP 43.8: Vortrag

Donnerstag, 21. März 2024, 17:15–17:30, H 0107

Unveiling the Role of Surface Hydrophobicity and Defects in Heterogeneous Cavitation by Atomistic Simulations — •Philip Loche^1,2, Matej Kanduč³, Emanuel Schneck⁴, and Roland R. Netz² — ¹EPFL, Lausanne, Switzerland — ²FU Berlin — ³Jožef Stefan Institute, Ljubljana, Slovenia — ⁴TU Darmstadt, Darmstadt, Germany

The reduction of pressure in liquids can lead to vaporization and the formation of bubbles, a phenomenon known as cavitation. Cavitation is commonly observed in hydraulic machinery, ship propellers, and even within biological systems. Liquids can sustain enormous negative pressures until reaching their stability limits, at which point cavitation occurs. While classical nucleation theory well explains the energetics of these events, little is known about the dynamics of interfacial bubble formation.

We quantify the kinetics of heterogeneous cavitation using classical nucleation theory and atomistic simulations of self-assembled monolayers at various contact angles under a constant rate protocol. Our focus is on the impact of surface hydrophobicity and defects. We find that increased hydrophobicity leads to a predominance of heterogeneous cavitation at surfaces. Simulations reveal an exponential relationship between the contact angle and the kinetic prefactor, with heightened hydrophobicity significantly reducing this parameter. The balance pressure, where homogeneous and heterogeneous cavitation rates converge, indicates a critical contact angle for switching between these two effects under realistic pressures and volumes.

Keywords: cavitation; water; atomistic simulations; bubbles