Properties of Blisters Formed on Polymer Films and Differentiating them from Nanobubbles/Nanodrops

Abstract

When studying surface nanobubbles on film-coated substrates, a class of bubble-like domains called blisters are probably forming at the solid–liquid interface together with nanobubbles. This may easily lead to a misunderstanding of the characteristics and applications of surface nanobubbles and thus continue to cause problems within the nanobubble community. Therefore, how to distinguish surface nanobubbles from blisters is a problem. Herein, the morphology and properties of blisters are investigated on both smooth and nanopitted polystyrene (PS) films in degassed water. The morphology and contact angle of blisters are similar to those of surface nanobubbles. However, blisters were observed to be punctured under the tip–blister interaction and be torn broken by an atomic force microscope tip during the process of scanning. At the same time, nanopits on the surface of blisters that formed on a pitted PS film can be seen clearly. These provide direct and visual evidence for distinguishing blisters from surface nanobubbles. In addition, surface nanobubbles and blisters on smooth and pitted PS films in air-equilibrated water are studied. No punctured surface nanobubble was observed, and the force curves obtained on surface nanobubbles and the change in height of blisters and surface nanobubbles under a large scanning force show that surface nanobubbles are much softer than blisters.

Study on the Formation and Properties of Trapped Nanobubbles and Surface Nanobubbles by Spontaneous and Temperature Difference Methods

“…As for the blister B 1 (Figure c), there is no obvious change in morphology at a setpoint of 85% and shows a slight decrease in both the lateral size and height at a setpoint of 80%, and then, it recovers to the original morphology at a setpoint of 95%. This is in line with the results in our recent study …”

“…This is in line with the results in our recent study. 46 Figure 5a shows that the contact angle, θ, of both trapped nanobubbles and surface nanobubbles keeps almost constant (about 11°) with the increase of bubble lateral size (left Yaxis); this indicates that the pits under trapped nanobubbles might have little or no effect on their contact angle. From the right Y-axis in Figure 5a, there is a linear function between the lateral size and the height of both the trapped nanobubble and surface nanobubble.…”

Interfacial Micropancakes: Gas or Contaminations?

“…Considering that there are no qualitative techniques currently available with both the high spatial resolution and the high chemical sensitivity to acquire reliably direct evidence to support the gas property of micropancakes, one can learn from the lessons in nanobubbles studies. In the early ages, the long lifespan existence of interfacial nanobubbles suffered similar disputes because the classical Epstein–Plesset theory predicts that the excessively high internal pressure inside the nanobubbles would cause their disappearance in a few microseconds. , Nowadays, the existence of surface nanobubbles had achieved wide acceptance by the scientific community, mainly because the in situ degassing controls combined with other technologies are capable of identifying the gas-filled entities. , Based on the atomic force microscopy (AFM) and other super-resolution techniques, the in situ measurements of the nanobubbles before and after the degassing procedure, are a convincible validation to avoid the dispute of the contamination issues. − An et al also agreed that the rigorous in situ degassing measurement was a reliable protocol to verify the gas essence of the surface nanobubbles. , Unfortunately, unlike the case in nanobubbles studies, there are few in situ degassing verification experiments for micropancakes because of the above-mentioned experimental challenges. In fact, in the first report of the micropancakes from our group, some degassing contrasts have been conducted.…”

Morphological and force spectroscopy characterizations for indentification of surface nanobubbles from nanodroplets and blisters

“…They are produced as water permeates through the thin film (i.e. a polystyrene film), wet and hence detach the thin films, leading to the formation of a water reservoir in between the supporting silicon substrate and the thin film [23,26]. So far it is still difficult to distinguish NBs from these spherical cap shaped nano-objects, especially from NDs.…”