Particle Size Determines the Shape of Supraparticles in Self-Lubricating Ternary Droplets

Lijun Thayyil Raju, Olga Koshkina, Huanshu Tan, Andreas Riedinger, Katharina Landfester, Detlef Lohse, Xuehua Zhang*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

35 Downloads (Pure)

Abstract

Supraparticles are large clusters of much smaller colloidal particles. Controlling the shape and anisotropy of supraparticles can enhance their functionality, enabling applications in fields such as optics, magnetics, and medicine. The evaporation of self-lubricating colloidal ouzo droplets is an easy and efficient strategy to create supraparticles, overcoming the problem of the "coffee-stain effect"during drop evaporation. Yet, the parameters that control the shape of the supraparticles formed in such evaporating droplets are not fully understood. Here, we show that the size of the colloidal particles determines the shape of the supraparticle. We compared the shape of the supraparticles made of seven different sizes of spherical silica particles, namely from 20 to 1000 nm, and of the mixtures of small and large colloidal particles at different mixing ratios. Specifically, our in situ measurements revealed that the supraparticle formation proceeds via the formation of a flexible shell of colloidal particles at the rapidly moving interfaces of the evaporating droplet. The time tc0 when the shell ceases to shrink and loses its flexibility is closely related to the size of particles. A lower tc0, as observed for smaller colloidal particles, leads to a flat pancake-like supraparticle, in contrast to a more curved American football-like supraparticle from larger colloidal particles. Furthermore, using a mixture of large and small colloidal particles, we obtained supraparticles that display a spatial variation in particle distribution, with small colloids forming the outer surface of the supraparticle. Our findings provide a guideline for controlling the supraparticle shape and the spatial distribution of the colloidal particles in supraparticles by simply self-lubricating ternary drops filled with colloidal particles.

Original languageEnglish
Pages (from-to)4256-4267
JournalACS nano
Volume15
Issue number3
Early online date19 Feb 2021
DOIs
Publication statusPublished - 23 Mar 2021

Keywords

  • UT-Hybrid-D
  • ouzo effect
  • self-lubrication
  • silica
  • supraparticles
  • ternary droplets
  • evaporation-induced colloidal self-assembly

Fingerprint Dive into the research topics of 'Particle Size Determines the Shape of Supraparticles in Self-Lubricating Ternary Droplets'. Together they form a unique fingerprint.

Cite this