Integrating PRISM theory and molecular dynamics simulations for studying assembly in solutions of block copolymers with varying sequences and composition

In this talk, we will present our recent work using Polymer Reference Interaction Site Model (PRISM) theory and molecular dynamics (MD) simulations to study amphiphilic block copolymers (BCPs) in solution. In both methods, we use a generic coarse-grained model to represent amphiphilic AB BCPs in implicit solvent with the solvophobicity of the B block captured using effective B-B attractions modeled using Lennard Jones potential. We study the assembly in solutions of amphiphilic BCPs as a function of increasing solvophobicity for varying BCP sequences (diblock and triblock) and composition (solvophobic-rich or solvophilic-rich). The comparison of inter-molecular pair correlations, g(r), and structure factors, S(k), shows excellent agreement between PRISM predictions and MD simulations at low solvophobicities. Even though PRISM theory fails to converge to a numerical solution at higher solvophobicities where we see assembled structures in MD simulations, the low solvophobicity results from PRISM predict most of the thermodynamic signatures of the solutions at higher solvophobicities. This shows that PRISM theory could be used to sweep a wide range of design parameters much faster than MD simulations, and predict structure and thermodynamics during assembly in copolymers solutions.