Interfacial Interaction Enhanced Rheological Behavior in PAM/CTAC/Salt Aqueous Solution- A Coarse-Grained Molecular Dynamics Study

Interfacial interactions within a multi-phase polymer solution play critical roles in processing control and mass transportation in chemical engineering. However, the understandings remain yet to be explored due to the complexity of system. In this study, we use an efficient analytical method - a nonequlibrium molecular dynamics (NEMD) simulation, to unveil the molecular interactions and rheology of a multiphase solution containing cetyltrimethyl ammonium chloride (CTAC), polyacrylamide (PAM), and sodium salicylate (NaSal). The associated macroscopic rheological characteristics and shear viscosity of polymer/surfactant solution are investigated, where the computational results agree well with the experimental data. The relation between characteristic time and shear rate is consistent with the power law. By simulating the shear viscosity of polymer/surfactant solution, we find that the phase transition of micelles within the mixture leads to non-monotonic increase in viscosity of the mixed solution with the increase of concentration of CTAC or PAM. We expect this optimized molecular dynamic approach to advance the current understandings on chemical-physical interactions within polymer/surfactants mixture at molecular level and enable emerging engineering solutions.