title: Characterization of spherical domains at the polystyrene thin film-water interface.
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.
authors.affiliation: Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education and School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, P.R. China; Department of Mechanical Engineering, Main Campus, University of Engineering and Technology, Peshawar, Pakistan.
authors.forename: Khurshid
authors.initials: K
authors.lastname: Ahmad
authors.affiliation: Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education and School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, P.R. China.
authors.forename: Xuezeng
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Ministry of Education and School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, P.R. China.
authors.forename: Yunlu
authors.initials: Y
authors.lastname: Pan
authors.affiliation: State Key Laboratory of Robotics and Systems and School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001, P.R. China.
authors.forename: Danish
authors.initials: D
authors.lastname: Hussain
keywords: AFM; blisters; contaminants; defects; nanobubbles; water permeation