Characterization of nanobubbles on hydrophobic surfaces in water.
The aim of this paper is to quantitatively characterize the appearance, stability, density, and shape of surface nanobubbles on hydrophobic surfaces under varying conditions such as temperature and temperature variation, gas type and concentration, surfactants, and surface treatment. The method we adopt is atomic force microscopy (AFM) operated in the tapping mode. In particular, we show (i) that nanobubbles can slide along grooves under the influence of the AFM tip, (ii) that nanobubbles can spontaneously form by substrate heating, allowing for a comparison of the surface topology with and without the nanobubble, (iii) that a water temperature increase leads to a drastic increase in the nanobubble density, (iv) that pressurizing the water with CO2 also leads to a larger nanobubble density, but typically to smaller nanobubbles, (v) that alcohol-cleaning of the surface is crucial for the formation of surface nanobubbles, (vi) that adding 2-butanol as surfactant leads to considerably smaller surface nanobubbles, and (vii) that flushing water over alcohol-covered surfaces strongly enhances the formation of surface nanobubbles.
Yang
Shangjiong
S
Faculty of Science and Technology, Department of Physics, MESA+ Institute for Nanotechnology, University of Twente, 7500 AE Enschede, The Netherlands.
Dammer
Stephan M
SM
Bremond
Nicolas
N
Zandvliet
Harold J W
HJ
Kooij
E Stefan
ES
Lohse
Detlef
D