From local to collective dynamics in Pluronic F127 water solutions: A multiscale experimental and simulation study

Understanding the interplay between structural organization and dynamical behavior of Pluronic F127 in aqueous solutions is crucial for controlling macroscopic properties and optimizing its performance in applications such as drug delivery and soft materials design. A multiscale description that consistently links local relaxation processes to collective dynamics is therefore crucial, and can be addressed by combining complementary experiments with molecular simulations. We investigate the temperature-driven evolution of Pluronic F127 in water-from dilute to concentrated, gel-like conditions-by combining Dynamic light scattering (DLS), Diffusing Wave Spectroscopy (DWS), and coarse-grained molecular dynamics (MD) simulations. DLS is used to probe the local dynamics of the system, while DWS captures the collective response of the system. In parallel, we develop a new coarse-grained MD model, specifically designed to reproduce the behavior of F127 in water, including the low-temperature regime. Large-scale simulations, involving systems of up to 178,000 beads and extending over microsecond timescales, enable direct access to the microscopic structure and dynamics of the system. DLS reveals distinct relaxation processes associated with local structural organization and their evolution with temperature. DWS identifies a transition from diffusive to subdiffusive and dynamically constrained regimes as concentration and temperature increase, indicating the emergence of increasingly connected structures. Simulations capture consistent qualitative trends in the dynamical evolution and provide molecular-level insight into aggregate structure and dynamics. While a direct quantitative correspondence is not expected, the combined approach offers a complementary multiscale perspective that links local and collective dynamics.