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Understanding the kinetics of nanobubbles encapsulated by ultrathin two-dimensional (2D) layered van der Waals crystal membranes on atomically flat substrates is important to the applications of 2D materials and the pursuit of 2D nanobubble technologies. Here, we investigate the controlled motion of monolayer molybdenum disulfide (MoS2)-encapsulated nanobubbles on flat hexagonal boron nitride substrates using atomic force microscopy (AFM). Our study reveals a distinct transition from standstill bubble deformations to stable, stepwise bubble translations on flat substrates. The membrane tension-dominated 2D nanobubble behaves like an elastic soft body in its collision interaction with the AFM tip. This delicate motion-control technique enables neighboring 2D nanobubbles to move closer and eventually coalesce into larger nanobubbles. These findings pave the way for high-precision manipulation of nanobubbles and facilitate the exploration of their emerging applications.
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Nanoscale Patterning of Surface Nanobubbles by Focused Ion Beam
Surface nanobubbles forming on hydrophobic surfaces in water present an exciting opportunity as potential agents of top-down and bottom-up nanopatterning. The formation and characteristics of surface nanobubbles are strongly influenced by the physical and chemical properties of the substrate. In this study, focused ion beam (FIB) milling is used for the first time to spatially control the nucleation of surface nanobubbles with 75 nm precision. The spontaneous formation of nanobubbles on alternating lines of a self-assembled monolayer (octadecyltrichlorosilane) patterned by FIB is detected by atomic force microscopy. The effect of chemical vs topographical surface heterogeneity on the formation of nanobubbles is investigated by comparing samples with OTS coating applied pre- vs post-FIB patterning. The results confirm that nanoscale FIB-based patterning can effectively control surface nanobubble position by means of chemical heterogeneity. The effect of FIB milling on nanobubble morphology and properties, including contact angle and gas oversaturation, is also reported. Molecular dynamics simulations provide further insight into the effects of FIB amorphization on surface nanobubble formation. Combined experimental and simulation investigations offer insights to guide future nanobubble-based patterning using FIB milling.
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- Award ID(s):
- 1943907
- PAR ID:
- 10526398
- Publisher / Repository:
- ACS
- Date Published:
- Journal Name:
- Langmuir
- Volume:
- 40
- Issue:
- 28
- ISSN:
- 0743-7463
- Page Range / eLocation ID:
- 14613 to 14622
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acs.langmuir.4c01534
