Structure, Dynamics, and Rheology of Realistic Gaussian-Core Fluids: Unexpected Anomalies and Their Macromolecular Origin

Abstract

We experimentally investigate the structure, dynamics, and linear rheology of dendrimer solutions as a model system of Gaussian-core fluids and ultrasoft colloids, and compare the results with those obtained by the coarsegrained approach. In the overpacked regime, particles pack in a way similar to Bernal's celebrated plasticine model. Meanwhile, the interparticle interaction displays a counterintuitive softening under densification. Such behaviors result in transport properties remarkably different from the predictions of the simple Gaussian-core model. Particularly, we find a strong coupling between the rearrangement of interparticle configuration and intraparticle dynamics. These unexpected observations demonstrate the decisive role of intraparticle complexity in the structure and dynamics of ultrasoft colloids.