Roughness induced rotational slowdown near the colloidal glass transition

Beybin Ilhan*, Frieder Mugele, Michael H.G. Duits

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

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.

Original languageEnglish
Pages (from-to)1709-1716
Number of pages8
JournalJournal of colloid and interface science
Volume607
Issue numberPart 2
DOIs
Publication statusPublished - Feb 2022

Keywords

  • CSLM
  • Glass transition
  • Particle tracking
  • Raspberry colloid
  • Rotational arrest
  • Rotational diffusion
  • Roughness
  • UT-Hybrid-D

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