Tuning Electrostatic Interactions in Soft Materials Beyond the Mean Field Theory

Electrostatic interactions provide tunability for the properties of soft materials in various industries and daily life, such as the dispersion of charged colloids in paints, the self-organization of liquid droplets in drug emulsions and phase separation in cells. Despite long-term usage of electrostatics in controlling the soft material properties, recent experimental observations of attractive interactions between like charges and between neutral droplets keep challenging the previously accepted classical theoretical understandings, inhibiting the systematic design of electrostatic-mediated soft materials.

In this talk, via our computational work based on our recently developed computational platform, I will show the importance of including charge correlation and dielectric heterogeneity to correctly and efficiently model electrostatic-mediated self-assembly in coarse-grained models. The models successfully predict the effects of concentrated electrolyte on the interactions between colloids, the effects of surface polarization on aggregation of ion-containing emulsion droplets, and the effects of the low dielectric medium on pH-regulated self-assembly of one-dimensional macrocycle nanotubes. The research aligns with recent experiments, and sheds light on why classical electrostatic theories, such as the Debye–Hückel theory and even the non-linear Poisson Boltzmann theory, break down in modern experiments. The work opens new venues for the computational design of the electrostatic-mediated self-organization and stimuli-responsiveness of soft materials that can be realized in experiments.