Sommaire:

I will present simulation results for a new, ultrasoft core model of polyelectrolytes in solutions. The model describes a mixture of polycations and polyanions with continuous Gaussian charge distributions in a dilute solution. The effective potential between the polyions is given by a long-range Coulombic tail and a bounded potential at short distances. The model thus shares some commonalities with other ultrasoft representations of interpenetrable colloidal particles, such as dendrimers, microgels and linear polymers. I will show that the ultrasoft primitive model displays aggregation processes that resemble the phenomenon of "complex coacervation" observed in polyelectrolytes in solution. A more systematic exploration of the phase diagram reveals a sharp conductor-insulator transition line that terminates near the top of a first order coexistence curve, separating a high-density liquid phase from a low-density vapor phase. The simulation data thus hint at a tricritical behavior, which contrasts with the Ising criticality of the widely studied "restricted primitive model", in which ions have hard cores.

Pour plus d'informations, merci de contacter Clusel M.