Reentrant Phase Diagram of Network Fluids

We introduce a microscopic model for particles with dissimilar patches which displays an unconventional “pinched” phase diagram, similar to the one predicted by Tlusty and Safran in the context of dipolar fluids [ Science 290 1328 (2000)]. The model—based on two types of patch interactions, which account, respectively, for chaining and branching of the self-assembled networks—is studied both numerically via Monte Carlo simulations and theoretically via first-order perturbation theory. The dense phase is rich in junctions, while the less-dense phase is rich in chain ends. The model provides a reference system for a deep understanding of the competition between condensation and self-assembly into equilibrium-polymer chains.