Lamellar order, microphase structures and glassy phase in a field theoretic model for charged colloids

TL;DR

This paper analytically explores a field theoretic model for charged colloids, revealing complex phase behaviors including lamellar, microphase, and glassy states, and suggesting microstructure formation influences colloidal gelation.

Contribution

It provides a detailed analytical phase diagram of a model with competing interactions, highlighting the potential equilibrium origin of observed colloidal microstructures.

Findings

Identification of lamellar, microphase, and glassy phases

Microstructure formation may underlie colloidal gelation

Model captures essential features of charged colloid interactions

Abstract

In this paper we present a detailed analytical study of the phase diagram and of the structural properties of a field theoretic model with a short-range attraction and a competing long-range screened repulsion. We provide a full derivation and expanded discussion and digression on results previously reported briefly in M. Tarzia and A. Coniglio, Phys. Rev. Lett. 96, 075702 (2006). The model contains the essential features of the effective interaction potential among charged colloids in polymeric solutions. We employ the self-consistent Hartree approximation and a replica approach, and we show that varying the parameters of the repulsive potential and the temperature yields a phase coexistence, a lamellar and a glassy phase. Our results suggest that the cluster phase observed in charged colloids might be the signature of an underlying equilibrium lamellar phase, hidden on experimental time scales, and emphasize that the formation of microphase structures may play a prominent role in the process of colloidal gelation.