Chemical reaction facilitates nanoscale mixing

To investigate the nature of mixing in reacting liquids, a two-dimensional system comprising two partly miscible liquids A and B that can form surface-active AB dimers was studied using Molecular Dynamics simulations. In the initial state, A and B occupied different parts of the system and were separated by a planar interface. Due to the A + B ↔ AB reaction, this interface became unstable and the liquids mixed. When the reaction was fast, it facilitated pronounced flows on molecular as well as larger scales. These non-equilibrium motions broke-up large, homogeneous regions into progressively smaller clusters surrounded by the AB dimers. This process substantially enhanced the mixing of A and B. The reaction created a variety of markedly different final morphologies depending on the reaction rate, component miscibility, and other parameters.