title: How soft repulsion enhances the depletion mechanism.
abstract: We investigate binary mixtures of large colloids interacting through soft potentials with small, ideal depletants. We show that softness has a dramatic effect on the resulting colloid-colloid effective potential when the depletant-to-colloid size ratio q is small, with significant consequences on the colloidal phase behaviour. We provide an exact relationship that allows us to obtain the effective pair potential for any type of colloid-depletant interaction in the case of ideal depletants, without having to rely on complicated and expensive full-mixture simulations. We also show that soft repulsion among depletants further enhances the tendency of colloids to aggregate. Our theoretical and numerical results demonstrate that--in the limit of small q--soft mixtures cannot be mapped onto hard systems and hence soft depletion is not a mere extension of the widely used Asakura-Oosawa potential.
authors.affiliation: Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna, Austria. lorenzo.rovigatti@univie.ac.at.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Rovigatti
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Gnan
authors.forename: Alberto
authors.initials: A
authors.lastname: Parola
authors.forename: Emanuela
authors.initials: E
authors.lastname: Zaccarelli