title: Selective Depletion Interactions in Mixtures of Rough and Smooth Silica Spheres.
abstract: The depletion interaction as induced between colloids by the addition of a polymer depletant is one of the few ways in which short-ranged attractions between particles can be controlled. Due to these tunable interactions, colloid-polymer mixtures have contributed to a better understanding of the role of attractions both in equilibrium phenomena such as phase transitions and liquid surfaces as well as in systems out of equilibrium such as gelation and the glass transition. It is known that, by simple geometric effects, surface roughness decreases the strength of the depletion interaction. In this study, we demonstrate both by Monte Carlo simulations and experiments that it is possible to generate enough difference in attraction strength to induce phase separation in smooth particles but not in rough particles. Roughness was induced by coating smooth particles with smaller spherical colloids. We indicate how effective potentials can be obtained through simulations and how the interplay between gravity and the depletion interaction with a flat container wall can be used to obtain a simple measure of the interaction strengths as a function of roughness.
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University , Princetonplein 1, 3584 CC Utrecht, The Netherlands.
authors.forename: Marlous
authors.initials: M
authors.lastname: Kamp
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University , Princetonplein 1, 3584 CC Utrecht, The Netherlands.
authors.forename: Michiel
authors.initials: M
authors.lastname: Hermes
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University , Princetonplein 1, 3584 CC Utrecht, The Netherlands.
authors.forename: Carlos M
authors.initials: CM
authors.lastname: van Kats
authors.affiliation: Soft Matter Physics, Huygens-Kamerlingh Onnes Lab, Leiden University , Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
authors.forename: Daniela J
authors.initials: DJ
authors.lastname: Kraft
authors.affiliation: Van 't Hoff Laboratory for Physical & Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University , Padualaan 8, 3584 CH Utrecht, The Netherlands.
authors.forename: Willem K
authors.initials: WK
authors.lastname: Kegel
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University , Princetonplein 1, 3584 CC Utrecht, The Netherlands.
authors.forename: Marjolein
authors.initials: M
authors.lastname: Dijkstra
authors.affiliation: Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University , Princetonplein 1, 3584 CC Utrecht, The Netherlands.
authors.forename: Alfons
authors.initials: A
authors.lastname: van Blaaderen