(316i) Effects of Shear on Carbon Nanotube Suspensions That Are Stabilized with  Surfactants Using DPD Simulations

Minh D. Vo, Dimitrios V. Papavassiliou

School of Chemical, Biological, and Materials Engineering

The University of Oklahoma,

Norman, OK -73019

Abstract

Due to strong van der Waals attractions, the agglomeration of carbon nanotubes (CNTs) in solvents is one of the first issues that needs to be resolved when using them in many industrial applications [1]. To overcome this problem, non-covalent stabilization of CNTs with surfactants has been shown to work in experiments. In our work, the stability of adsorded surfactant on CNT surface under shear was investigated in the meso-scopic scale with dissipative particle dynamics (DPD) simulation techniques. The CNT was considered as a close ended cylinder with diameter of 10 nm and length of 50 nm. Following our previous work [2-5], all necessary interaction parameters for the system of water, CNT and commercial surfactants (Alfoterra 123-8s and Tergitol 15-s-40) in DPD calculation were determined. A binary surfactant system with different molar ratio was released into the solution in the presence of a CNT at the center of the simulation box. After the equilibrium of surfactant adsorption was reached, all of supernatant surfactant was removed from the simulation. Then, a single CNT with adsorded surfactants was released into a Couette flow. Observing the status of adsorded surfactants, the threshold shear rate for surfactant desorption was determined with different molar ratios of binary surfactant. Besides, the mechanism of surfactant desorption was explored. The differences with polymer desorption from carbon nanotubes under shear will be highlighted in the presentation. This work can provide insights for the use of surfactants to stabilize carbon nanotube suspensions in practical applications, where the suspension flows and undergoes shear.

ACKNOWLEDGEMENTS

The financial support of the Advanced Energy Consortium (AEC BEG08-022) and the computational support of XSEDE (CTS090017) are acknowledged.

REFERENCES

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5. Vo, M., and D.V. Papavassiliou, Molecular Simulation (2016), 42(9), 734-744, 2016