Paper Number
EF21 

Session
Emulsions, Foams & Interfacial Rheology

Title
Nanoparticle-surfactant films: Coalescence and interfacial rheology

Presentation Date and Time
February 14, 2017 (Tuesday) 1:55

Track / Room
Track 4 / Sandhill Crane

Authors (Click on name to view author profile)

1. Forth, Joe (Lawrence Berkeley National Laboratory, Materials Science Division)
2. Toor, Anju (University of California, Mechanical Engineering Dept)
3. Russell, Thomas P. (University of Massachusetts Amherst, Polymer Science and Engineering Department)
4. Bochner de Araujo, Simone (Stanford University, Chemical Engineering)
5. Merola, Maria C. (Stanford University, Chemical Engineering)
6. Fuller, Gerald G. (Stanford University, Department of Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Joe Forth¹, Anju Toor², Thomas P. Russell³, Simone Bochner de Araujo⁴, Maria C. Merola⁴, and Gerald G. Fuller^4
1Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA; ²Mechanical Engineering Dept, University of California, Berkeley, CA; ³Polymer Science and Engineering Department, University of Massachusetts Amherst, Amherst, MA; ⁴Chemical Engineering, Stanford University, Stanford, CA 94305

Speaker / Presenter 
Merola, Maria C.

Text of Abstract
Nanoparticles Surfactants (‘NPSs’) are fascinating systems consisting of nanoparticles dispersed in one liquid phase, and functionalized surface-active polymers, known as ‘ligands’ dispersed in a second, immiscible fluid phase. NPSs are ideal candidates to generate fluid bi-continuous structures, also termed ‘bijels”. Such systems can be achieved by using emulsification processes, mechanical shearing or 3D printing. Subsequent external stimuli can also be used to dynamically reconfigure the spatial distribution of the fluids. Particles and ligands interact at a liquid-liquid (in our case, water-oil) interface to form the NPSs and the assembly of the NPSs results in the formation of a viscoelastic monolayer of NPSs.

In this work, we combine Pendant Drop Tensiometry, Interfacial Shear Rheology and Coalescence measurements to investigate the rheology and stability of the NPSs films, with a goal to understand the macroscopic structures that they stabilize.

We present results demonstrating that the formation of NPSs significantly reduces water-oil interfacial tension. Moreover, interfacial shear rheology indicates that the NPSs rapidly form strongly elastic interfaces. These interfaces were found to be very robust and able to quickly recover their interfacial moduli following large-amplitude shearing. Aging time independence of the film stability and structure upon coalescence are reported, and the films were found to be moderately stable against coalescence.

This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division, of the U.S. Department of Energy under Contract No. DE-AC02-05-CH11231 within the Adaptive Interfacial Assemblies Towards Structuring Liquids program (KCTR16).