Abstract
Spherical domains that readily form at the polystyrene (PS)–water interface were studied and characterized using atomic force microscopy (AFM). The study showed that these domains have similar characteristics to micro- and nanobubbles, such as a spherical shape, smaller contact angle, low line tension, and they exhibit phase contrast and the coalescence phenomenon. However, their insensitivity to lateral force, absence of long-range hydrophobic attraction, and the presence of possible contaminants and scratches on these domains suggested that these objects are most likely blisters formed by the stretched PS film. Furthermore, the analysis of the PS film before and after contact with water suggested that the film stretches and deforms after being exposed to water. The permeation of water at the PS–silicon interface, caused by osmosis or defects present on the film, can be a reasonable explanation for the nucleation of these spherical domains.
Highlights
Thin films of several nanometer thickness have long been a topic of interest for researchers
Where, R1 is the lateral size/radius of the domain without tip correction, h is the height of the spherical domain, and rt is the nominal radius of the tip
The analysis showed a very small contact angle when measuring from the inner side of the spherical domain
Summary
Thin films of several nanometer thickness have long been a topic of interest for researchers. The application of such thin films has been demonstrated in nonvolatile memory devices [1], sensors [2,3], for the modification of emissive properties of glass [4,5], and for the modification of surface properties [6,7,8] (e.g., hydrophobicity, oleophobicity). Thin PS films have been prepared by spin coating [11,12,13,14,15]. These films have been used in different studies related to surface and interface science, for example, to study boundary slip and micro-/nanobubble forma-
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