Nanobubble assisted nanopatterning utilized for ex situ identification of surface nanobubbles

Nanobubble assisted nanopatterning of polystyrene (PS) film allows visualization of nanobubble positions and identification of their appearance on the surface ex post by atomic force microscopy (AFM) imaging ex situ. Due to the PS nanograin size, ∼101 nm, nanobubbles of diameter less than 50 nm can be resolved, as well as microbubbles and micropancakes. The time scale of the nanopattern formation was found to be in the seconds range. This relatively short exposure time thus provides the possibility of also resolving some aspects of microbubble and nanobubble dynamics. In this work we demonstrate that ex post, ex situ AFM imaging of a PS surface after its exposure to deionized water allows us to examine nanobubble and microbubble formation, distribution and arrangement without any influence of the AFM scanning tip and under experimental conditions where in situ AFM imaging is not feasible, e.g. in liquid flow. (paper)