Kamp Marlous, Hermes Michiel, van Kats Carlos M, Kraft Daniela J, Kegel Willem K, Dijkstra Marjolein, van Blaaderen Alfons
Soft Condensed Matter, Debye Institute for Nanomaterials Science, Utrecht University , Princetonplein 1, 3584 CC Utrecht, The Netherlands.
Soft Matter Physics, Huygens-Kamerlingh Onnes Lab, Leiden University , Niels Bohrweg 2, 2333 CA Leiden, The Netherlands.
Langmuir. 2016 Feb 9;32(5):1233-40. doi: 10.1021/acs.langmuir.5b04001. Epub 2016 Jan 25.
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.
通过添加聚合物耗尽剂在胶体之间诱导产生的耗尽相互作用，是控制颗粒间短程吸引力的少数方法之一。由于这些可调节的相互作用，胶体 - 聚合物混合物有助于更好地理解吸引力在平衡现象（如相变和液体表面）以及非平衡系统（如凝胶化和玻璃化转变）中的作用。众所周知，通过简单的几何效应，表面粗糙度会降低耗尽相互作用的强度。在本研究中，我们通过蒙特卡罗模拟和实验都证明，有可能在光滑颗粒中产生足够大的吸引力强度差异以诱导相分离，而在粗糙颗粒中则不会。通过用较小的球形胶体包覆光滑颗粒来引入粗糙度。我们指出如何通过模拟获得有效势，以及重力与与平坦容器壁的耗尽相互作用之间的相互作用如何用于获得作为粗糙度函数的相互作用强度的简单度量。
