Stochastic coarse-grained simulations of polyelectrolytes

Stochastic coarse-grained simulations are implemented to investigate the behavior of both strong and weak polyelectrolytes in acqueous solution. A primitive electrolyte model is used to represent polyeletrolytes and mobile ions, whereas the solvent is implcitly represented by a dielectric continuum. The polyelectrolytes dissociation equilibria are taken into account by the constant-pH method where necessary. Several different chemico-physical systems have been investigated: 1. linear and star weak polyelectrolytes (both in solutions or confined in semi-permeable spherical cavities) able to interact via charged hydrogen bonds; 2. linear and star weak polyelectrolytes interacting with an oppositely charged macroion, the latter represented either via the usual charge-centered model or via monovalent charges tethered to (but free to move and rearrange on) its surface: 3. linear and star strong polyelectrolytes interacting with a primitive model of a zwitterionic micelle; 4. mixtures of oppositely charged star-shaped strong polyelectrolytes that self-assemble to form gel-like phases at the free swelling equilibrium; 5. weak knotted ring polyelectrolytes, the latter showing a non monotonic behavior of their size versus their ionization degree, an evidence that was not predicted by mean-filed approaches. Overall, our simulations demonstrated that the polyelectrolytes behavior often deviates from the one expected for "canonical" polyelectrolytes in diluted aqueous solutions when chemically specific interactions (such as charged hydrogen bonds) have to be taken into account, or when charge correlation play a fiundamental role.