Generation of Fermat's spiral patterns by solutal Marangoni-driven coiling in an aqueous two-phase system.

Xiao, Yang; Ribe, Neil M; Zhang, Yage; Pan, Yi; Cao, Yang; Shum, Ho Cheung · Nat Commun · 2022

basic_science · Level V

Where this comes from

Abstract

The solutal Marangoni effect is attracting increasing interest because of its fundamental role in many isothermal directional transport processes in fluids, including the Marangoni-driven spreading on liquid surfaces or Marangoni convection within a liquid. Here we report a type of continuous Marangoni transport process resulting from Marangoni-driven spreading and Marangoni convection in an aqueous two-phase system. The interaction between a salt (CaCl<sub>2</sub>) and an anionic surfactant (sodium dodecylbenzenesulfonate) generates surface tension gradients, which drive the transport process. This Marangoni transport consists of the upward transfer of a filament from a droplet located at the bottom of a bulk solution, coiling of the filament near the surface, and formation of Fermat's spiral patterns on the surface. The bottom-up coiling of the filament, driven by Marangoni convection, may inspire automatic fiber fabrication.