Paper Number
SF25
Session
Surfactants, Foams, and Emulsions
Title
Manipulating the colloidal interaction in macro- and nano-emulsions
Presentation Date and Time
October 22, 2019 (Tuesday) 4:10
Track / Room
Track 5 / Room 306A
Authors
- Salimi-Kenari, Hamed (New Mexico State University, Department of Chemical and Materials Engineering)
- Foudazi, Reza (New Mexico State University, Department of Chemical and Materials Engineering)
Author and Affiliation Lines
Hamed Salimi-Kenari and Reza Foudazi
Department of Chemical and Materials Engineering, New Mexico State University, Las Cruces, NM 88003
Speaker / Presenter
Salimi-Kenari, Hamed
Text of Abstract
The colloidal assembly is a major route to fabricate materials with tailored functionality. Compared to other conventional colloidal dispersions, nanoemulsions have unique rheological behavior due to nanoscale droplets and significant interdroplet interactions. In this work, we investigate the complex colloidal behavior of nanoemulsions by controlling the depletion attraction, electrostatic repulsion, and oscillatory structural forces within the semi-dilute and concentrated regimes. Therefore, the aggregation behavior, coalescence, and the structure-flow relationship of nanoemulsions are examined through flow curve and oscillatory shear measurements. We change the interdroplet interactions as a function of surfactant type and concentration for droplet sizes ranging from micrometer to nanometer. Therefore, the nature of the aggregation process and the cluster size distribution and its moments are investigated. In the studied range of surfactant concentrations, rheology of emulsions with narrow size distribution shows the flocculation and transition from colloidal gels to a glassy state. In contrast to the rheology of repulsive emulsions, by inducing the depletion interaction at a high concentration of surfactants, the attractive emulsions exhibit tenuous aggregation and gel behavior below the random close packing volume fraction.