Discrete Electrolytes Research

Liquid ionics beyond Poisson-Boltzmann

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Publications: 2011

18.

J.R.T. Seddon, H.J.W. Zandvliet, & D. Lohse
"Knudsen gas provides nanobubble stability"
Phys. Rev. Lett. 107, 116101 (2011)

We provide a model for the remarkable stability of surface nanobubbles to bulk dissolution. The key to the solution is that the gas in a nanobubble is of Knudsen type. This leads to the generation of a bulk liquid flow which effectively forces the diffusive gas to remain local. Our model predicts the presence of a vertical water jet immediately above a nanobubble, with an estimated speed of ~3.3 m/s, in good agreement with our experimental atomic force microscopy measurement of ~2.7 m/s. In addition, our model also predicts an upper bound for the size of nanobubbles, which is consistent with the available experimental data.

17.

J.R.T. Seddon, E.S. Kooij, B. Poelsema, H.J.W. Zandvliet, & D. Lohse
"Surface bubble nucleation stability"
Phys. Rev. Lett. 106, 056101 (2011)

Recent research has revealed several different techniques for nanoscopic gas nucleation on submerged surfaces, with findings seemingly in contradiction with each other. In response to this, we have systematically investigated the occurrence of surface nanobubbles on a hydrophobized silicon substrate for various different liquid temperatures and gas concentrations, which we controlled independently. We found that nanobubbles occupy a distinct region of this parameter space, occurring for gas concentrations of approximately 100%-110%. Below the nanobubble region we did not detect any gaseous formations on the substrate, whereas micropancakes (micron wide, nanometer high gaseous domains) were found at higher temperatures and gas concentrations. We moreover find that supersaturation of dissolved gases is not a requirement for nucleation of bubbles.

16.

M.A.J. van Limbeek & J.R.T. Seddon
"Surface nanobubbles as a function of gas type"
Langmuir 27, 8694 (2011)

We experimentally investigate the nucleation of surface nanobubbles on PFDTS-coated silicon as a function of the specific gas dissolved in water. In each case, we restrict ourselves to equilibrium conditions (c = 100%, Tliquid = Tsubstrate). Not only is nanobubble nucleation a strong function of gas type, but there also exists an optimal system temperature of ~35-40oC where nucleation is maximized, which is weakly dependent on gas type. We also find that the contact angle is a function of the nanobubble radius of curvature for all gas types investigated. Fitting this data allows us to describe a line tension that is dependent on the type of gas, indicating that the nanobubbles sit on top of adsorbed gas molecules. The average line tension was τ ~ 0.8 nN.

15.

J.R.T. Seddon & D. Lohse
"Nanobubbles and micropancakes: gaseous domains on immersed substrates"
J. Phys.: Condens. Matter 23, 133001 (2011)
→ Invited Topical Review

Surface nanobubbles and micropancakes are two recent discoveries in interfacial physics. They are nanoscopic gaseous domains that form at the solid/liquid interface. The fundamental interest focuses on the fact that they are surprisingly stable to dissolution, lasting for at least 10-11 orders of magnitude longer than the classical expectation. So far, many articles have been published that describe various different nucleation methods and ‘ideal’ systems and experimental techniques for nanobubble research, and we are now at the stage where we can begin to investigate the fundamental questions in detail. In this topical review, we summarize the current state of research in the field and give an overview of the partial answers that have been proposed or that can be inferred to date. We relate nanobubbles and micropancakes, and we try to build a framework within which nucleation may be understood. We also discuss evidence for and against different aspects of nanobubble stability, as well as suggesting what still needs to be done to obtain a full understanding.