Paper Number
GR11 

Session
Gallery of Rheology Contest

Title
Binary colloidal gel network

Presentation Date and Time
October 13, 2021 (Wednesday) 6:30

Track / Room
Gallery of Rheology / Ballroom Pre Function

Authors (Click on name to view author profile)

1. Cho, Jae Hyung (Massachusetts Institute of Technology, Mechanical Engineering)
2. Bischofberger, Irmgard (Massachusetts Institute of Technology, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Jae Hyung Cho and Irmgard Bischofberger
Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139

Speaker / Presenter 
Cho, Jae Hyung

Keywords
colloids; gels

Text of Abstract
When mixed in water, two different types of polystyrene-poly(N-isopropylacrylamide) core-shell colloidal particles of similar sizes can form a binary gel network due to attractive van der Waals interactions. Our poster displays a confocal fluorescent micrograph of the two types of particles that vary in attraction strength, hence named “strong” and “weak” particles, that form a space-spanning network at the total volume fraction of 1%. The system contains an equal volume of the strong and the weak particles that are labelled with green and red fluorescent dyes, respectively, and that are separately visualized using different filters. As shown in the merged image, the two types of particles are uniformly mixed despite the difference in their attraction strengths. This homogeneous composition of the binary gels allows us to tune their mean attraction strengths, and thus their viscoelasticity, by changing the mixing proportion of the two types [Cho and Bischofberger, Phys. Rev. E 103, 032609 (2021)].