Field-Theoretic Simulations of Triblock Polyelectrolyte Gels

Rather than forming gels using the traditional methods of covalent crosslinks or hydrophobic/hydrophillic interactions, we study polyelectrolyte gels that are formed using electrostatic interactions. In particular, we use a system of oppositely charged, triblock polyelectrolytes with charged endblocks and neutral, hydrophilic midblocks in solution. Under the right conditions, the charged endblocks can aggregate together to form dense, endblock rich micelles called coacervates. The neutral midblocks are excluded from the micelles, but due to chain connectivity, they can form bridges between the coacervate micelles, thus creating a microphase separated gel. Since the coacervate domains are formed by electrostatic interactions, the strength of the coacervate, and therefore the properties of the gel, can be tuned by varying salt concentration, pH and temperature. We investigate the microstructures and solution sensitivity of the triblock polyelectrolytes in an implicit solvent using field-theoretic simulations (FTS). Since the formation of the coacervate domains is driven by charge correlations, the mean-field assumption fails, and it is necessary for us to study the system beyond the level of self-consistent field theory (SCFT).