Fig. 5: Coalescence mechanism.
From: Elastocapillary cleaning of twisted bilayer graphene interfaces
a Schematic of the driving force for the coalescence process. \({T}_{{{\mathrm{pre}}}}\) denotes the pretension applied to both nanopockets. \({T}_{1\to 2}^{L}\) denotes the tension from nanopocket 1 to the left of nanopocket 2, whereas \({T}_{1\to 2}^{R}\,\) denotes the tension from nanopocket 1 to the right of nanopocket 2. \({F}_{e}\) represents the elastic force of graphene sheets. \({F}_{c}\) represents the capillary force of trapped liquids. \({\beta }_{L}\) and \({\beta }_{R}\) represent the effective contact angles of the left and right sides of nanopocket 2, respectively. b Molecular dynamics simulation snapshots showing the side and top views of droplets during coalescence with a small inter-pocket distance \(d\) (compared with the radius of droplets, a = 4 nm). The atoms are colored by their displacement out of the bilayer plane. c Comparison of the coalescence processes of nanodroplets intercalated in a graphene bilayer with or without pretension. The atoms are colored by their position out of the bilayer plane, where the color range is set to be smaller than the height of blisters to show the fringe of nanopockets and wrinkle patterns. d Relative potential energy landscape of the nanopocket-containing bilayers as a function of d under 0, 1, and 2% pretension conditions, where the represented symbols connected with solid lines are simulation measurements, and the dashed lines are energy predictions for larger d according to the trend of solid lines. The simulation snapshots are shown in the inset. The reference potential energy is measured at d = 0 (the merged state), which is −4.678 × 106, −4.674 × 106, and −4.661 × 106 eV for 0, 1, and 2% pretension, respectively.
