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.

How soft repulsion enhances the depletion mechanism / Rovigatti, Lorenzo; Gnan, Nicoletta; Parola, Alberto; Zaccarelli, Emanuela. - In: SOFT MATTER. - ISSN 1744-683X. - 11:4(2015), pp. 692-700-700. [10.1039/c4sm02218a]

How soft repulsion enhances the depletion mechanism

Rovigatti, Lorenzo;Gnan, Nicoletta;PAROLA, ALBERTO;Zaccarelli, Emanuela
2015

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.
2015
colloids; depletion interactions; polymers
01 Pubblicazione su rivista::01a Articolo in rivista
How soft repulsion enhances the depletion mechanism / Rovigatti, Lorenzo; Gnan, Nicoletta; Parola, Alberto; Zaccarelli, Emanuela. - In: SOFT MATTER. - ISSN 1744-683X. - 11:4(2015), pp. 692-700-700. [10.1039/c4sm02218a]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1275982
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