Structure, phase behavior and inhomogeneous fluid properties of binary dendrimer mixtures

TL;DR

This study investigates the phase behavior and inhomogeneous properties of binary dendrimer mixtures using Gaussian effective potentials and density functional theory, revealing phase separation and pattern formation under confinement.

Contribution

It introduces a Gaussian potential-based approach to model dendrimer mixtures and explores their phase behavior and structure with theoretical and simulation methods.

Findings

Good agreement between DFT and simulations for bulk structure

Identification of macro- and micro-phase separation

Observation of pattern formation in confined micro-phase separated systems

Abstract

The effective pair potentials between different kinds of dendrimers in solution can be well approximated by appropriate Gaussian functions. We find that in binary dendrimer mixtures the range and strength of the effective interactions depend strongly upon the specific dendrimer architecture. We consider two different types of dendrimer mixtures, employing the Gaussian effective pair potentials, to determine the bulk fluid structure and phase behavior. Using a simple mean field density functional theory (DFT) we find good agreement between theory and simulation results for the bulk fluid structure. Depending on the mixture, we find bulk fluid-fluid phase separation (macro-phase separation) or micro-phase separation, i.e., a transition to a state characterized by undamped periodic concentration fluctuations. We also determine the inhomogeneous fluid structure for confinement in spherical cavities. Again, we find good agreement between the DFT and simulation results. For the dendrimer mixture exhibiting micro-phase separation, we observe rather striking pattern formation under confinement.