Abstract

In this seminar, I discuss the structure and dynamics of a hard colloid–star polymer mixture in the protein limit, where the hard component is smaller than the soft one. Soft–hard mixtures exhibit rich dynamical behavior governed by parameters such as the concentrations of the two components, interaction softness, and size ratio. I focus on the regime of arrested phase separation, where an incipient demixing transition competes with a nearby vitrification line. Using coarse-grained molecular dynamics simulations, I characterize both single-particle and collective dynamics of the hard colloidal tracers within the soft glassy matrix. I show that arrested phase separation induces population splitting and a decoupling between self and collective dynamics of the hard colloids. Overall, the interplay between glassiness and arrested phase separation gives rise to complex, multiscale dynamical phenomena that strongly affect the motion of hard additives in the arrested soft matrix. Reference: K. Moser, C.N. Likos, V. Sposini, arXiv:2601.07625 (2026).