Dynamic heterogeneity and viscosity decoupling: origin and analytical prediction

The molecular-level structure and dynamics decide the functionality of solvent media. Therefore, a significant amount of effort is being dedicated continually over time in understanding their structural and dynamical features. One intriguing aspect of solvent structure and dynamics is heterogeneity. In these systems, the dynamics follow tau proportional to (eta/T)(p), where p is the measure of viscosity decoupling. We analytically predicted that in such cases, the Stokes-Einstein relationship is modified to log(tau(mu)) = log(eta(bulk)/T) + E-mu - E-bulk/2.303RT+ log C due to microdomain formation, and the second term on the right-hand side leads to viscosity decoupling. We validated our prediction by estimating the p values of a few solvents, and they matched well with the literature. Overall, we believe that our approach gives a simple yet unique physical picture to help us understand the heterogeneity of solvent media.

Automated summary

The molecular-level structure and dynamics of solvent media greatly influence their functionality. Understanding the heterogeneity of solvent structure and dynamics is important, and analytical predictions have provided insights into viscosity decoupling. This approach offers a simple yet unique physical picture for understanding solvent media.