Fig. 3.

Molecular structure cartoons of the droplets’ interface. (A) The interfacial monolayer at $T>T_s$, comprising mixed C₁₆ alkane and C₁₈TAB surfactant molecules. Yellow, blue, green, and red denote C, H, N⁺, and Br⁻, respectively. C₁₈TAB headgroups are partially water-ionized and hydrated. (B) Only the interface freezes at $T=T_s$, forming a crystalline, hexagonally packed, monolayer of extended, interface-normal, molecules (4) (Inset). Because a spherical surface cannot be tiled by hexagons, the frozen monolayer includes 12 fivefold defects. (C) At low γ elasticity dominates. The defect-induced strain is partly relieved by buckling (Inset).