Speaker: Emanuela Zaccarelli
Computer simulations of thermoresponsive polymer networks
Microgels are soft particles individually made by cross-linked polymer networks which are nowadays widely used as colloidal model systems because of their responsivity to external control parameters. In particular, thermoresponsive microgels undergo a reversible Volume Phase Transition from a swollen to a collapsed state at a given temperature. Recently, we introduced a numerical protocol to synthesize microgels in silico, providing a realistic description of the particles in comparison to experiments, and we also put forward a way to numerically calculate their elastic moduli. In addition to microgels, we also investigate hydrogels, i.e., bulk polymer networks. By calculating their elastic properties, we find the emergence of auxetic behavior under tension for hydrogels with a low degree of crosslinking. When the limit of auxeticity is reached (Poisson's ratio =−1), a condition that we call "hyper-auxeticity”, the mechanical instability triggers the onset of critical-like fluctuations between two networks of different densities.
Seminar room at ground floor, Via dei Taurini 19.
