Molecular dynamics simulation of polyelectrolyte with oppositely charged monomeric and dimeric surfactants

Interactions of anionic polyelectrolyte (PE) with cationic monomeric (MS) and dimeric surfactants (DS) have been investigated by coarse-grained molecular dynamics (MD) simulation. A PE/surfactant mixture is observed to evolve over time into micellar complex of increasing size. The critical aggregation concentration (CAC) is qualitatively found to be much lower than the critical micellization concentration (CMC) of the free surfactant. Compared to the monomeric analog, a DS interacts more strongly with the oppositely charged polyion chain. The equilibrium complex size becomes larger with increasing surfactant concentration. Simulation results are consistent with experimental observations and reveal that the electrostatic and hydrophobic interactions play an important role in the formation of micellar complex.