Tuning the rheology and microstructure of particle-laden fluid interfaces with Janus particles

Yiming Qiao; Xiaolei Ma; Zhengyang Liu; Michael A Manno; Nathan C Keim; Xiang Cheng

doi:10.1016/j.jcis.2022.03.041

Tuning the rheology and microstructure of particle-laden fluid interfaces with Janus particles

J Colloid Interface Sci. 2022 Jul 15:618:241-247. doi: 10.1016/j.jcis.2022.03.041. Epub 2022 Mar 14.

Authors

Yiming Qiao¹, Xiaolei Ma¹, Zhengyang Liu¹, Michael A Manno¹, Nathan C Keim², Xiang Cheng³

Affiliations

¹ Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA.
² Department of Physics, Pennsylvania State University, University Park, PA 16802, USA. Electronic address: keim@psu.edu.
³ Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA. Electronic address: xcheng@umn.edu.

PMID: 35339960
DOI: 10.1016/j.jcis.2022.03.041

Abstract

Hypothesis: Particle-laden fluid interfaces are the central component of many natural and engineering systems. Understanding the mechanical properties and improving the stability of such interfaces are of great practical importance. Janus particles, a special class of heterogeneous colloids, might be used as an effective surface-active agent to control the assembly and interfacial rheology of particle-laden fluid interfaces.

Experiments: Using a custom-built interfacial stress rheometer, we explore the effect of Janus particle additives on the interfacial rheology and microscopic structure of particle-laden fluid interfaces.

Findings: We find that the addition of a small amount of platinum-polystyrene (Pt-PS) Janus particles within a monolayer of PS colloids (1:40 number ratio) can lead to more than an order-of-magnitude increase in surface moduli with enhanced elasticity, which improves the stability of the interface. This drastic change in interfacial rheology is associated with the formation of local particle clusters surrounding each Janus particle. We further explain the origin of local particle clusters by considering the interparticle interactions at the interface. Our experiments reveal the effect of local particle structures on the macroscopic rheological behaviors of particle monolayers and demonstrate a new way to tune the microstructure and mechanical properties of particle-laden fluid interfaces.

Keywords: Interfacial rheology; Interparticle interactions; Janus particles.