Understanding the thermoresponsive behavior of L61/Water mixtures via MD and DPD simulations: A two-scale approach

Pluronics are nonionic amphiphilic copolymers with many applications in the pharmaceutical and cosmetic industry. In water these polymers may exist as unimers, micelles, and other supramolecular aggregates. The study of such phases by means of in-silico methods, like molecular dynamics and dissipative particle dynamics, can be expected to complement existing experimental data and better understand their molecular properties. In this work, we propose a two-scale approach where these two methods are combined to allow for the efficient study of Pluronics dynamics at different temperatures. The method is applied to study the thermoresponsive behavior of L61 in water. In line with the experimental data, our simulations show that L61 does not form micelles upon heating. At the highest concentration considered, a two-phase system is observed, where small and large aggregates coexist. This outcome and the applicability of the method to other Pluronics are discussed in the light of the existing literature.