“Micro-Pottery”Marangoni Effect Driven Assembly of Amphiphilic Fibers

We report spontaneous supra-assembly of fibrous surfactant crystallites at the air−solution interface resulting in spectacular arrays of two-dimensional spiral and three-dimensional “micro-pottery”-like superstructures. Surface pressure differential driven bending of the embryonic fiber nuclei and Marangoni convection driven fiber migration/alignment appear to be the causal factors behind this phenomenon. The assemblies form at specific crystal-growth velocities dictated by the relative time scales for fiber bending/alignment and their rigidification/immobilization as they grow. Although our studies are restricted to a specific class of amphiphiles, namely, alkaline metal salts of linear fatty acids, the phenomenon should be generic to amphiphilic molecules that crystallize into flexible fibers.