Roughness induced rotational slowdown near the colloidal glass transition

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:607

Article

Ilhan, Beybin¹  Mugele, Frieder¹  Duits, Michael H. G.¹ 

[1] Univ Twente, Fac Sci & Technol, MESA Inst Nanotechnol, Phys Complex Fluids, NL-7500 AE Enschede, Netherlands

关键词: Rotational diffusion;    Rotational arrest;    Raspberry colloid;    Glass transition;    Roughness;    CSLM;    Particle tracking;   

DOI  :  10.1016/j.jcis.2021.08.212

来源: Elsevier

【 摘 要 】

Hypothesis: In concentrated suspensions, the dynamics of colloids are strongly influenced by the shape and topographical surface characteristics of the particles. As the particles get into close proximity, surface roughness alters the translational and rotational Brownian motions in different ways. Eventually, the rotations will get frustrated due to geometric hindrance from interacting asperities. Experiments: We use model raspberry-like colloids to study the effect of roughness on the translational and rotational dynamics. Using Confocal Scanning Laser Microscopy and particle tracking, we simultaneously resolve the two types of Brownian motion and obtain the corresponding Mean Squared Displacements for varying concentrations up to the maximum packing fraction. Findings: Roughness not only lowers the concentration of the translational colloidal glass transition, but also generates a broad concentration range in which the rotational Brownian motion changes signature from high-amplitude diffusive to low-amplitude rattling. This hitherto not reported second glass transition for rough spherical colloids emerges when the particle intersurface distance becomes comparable to the roughness length scale. Our work provides a unifying understanding of the surface characteristics' effect on the rotational dynamics during glass formation and provides a microscopic foundation for many roughness-related macroscale phenomena in nature and technology. (c) 2021 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).

【 授权许可】

Free