An extended Stokes–Einstein model for condensed ionic water structures with topological complexity

Abstract

Abstract ‘What is the structure of water?’ This has been a perplexing question for a long time and water structure with various phases is a great topic of research interest. Topological complexity generally occurs because hydrophilic ions strongly influence the size and shape of condensed water structures owing to their kosmotropic and chaotropic transitions. In this study, an extended Stokes–Einstein model incorporating Flory–Huggins free energy equation is proposed to describe the constitutive relationship between dynamic diffusion and condensed water structure with a topological complexity. The newly developed model provides a geometrical strategy of end-to-end distance and explores the constitutive relationship between condensed ionic water structures and their dynamic diffusion behaviors. A free-energy function is then formulated to study thermodynamics in electrolyte aqueous solution, in which the condensed ionic water structures undergo topologically complex changes. Finally, effectiveness of the proposed model is verified using both molecular dynamics simulations and experimental results reported in literature.