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Darsh T. Wasan, Ph.D.

Distinguished Professor
Motorola Chair Professor of Chemical Engineering
Vice President for International Affairs


Room 228 Perlstein Hall







Ph.D. from University of California, Berkeley (Chemical Engineering, 1965)
B.S. from University of Illinois, Urbana (Chemical Engineering, 1960)


Colloidal processing, including particle suspensions, foams and emulsions

Wetting, spreading and adhesion of liquids Containing nanoparticles on solids

Thin liquid films

Interfacial and film rheology


Professor Wasan, who is currently serving as editor-in-chief of the Journal of Colloid and Interface Science, has research interests in the areas of interfacial and colloidal phenomena, foams, emulsions and dispersions, and food and environmental technologies. His present research activities in these areas are:

Thin Liquid Films, Foams, Emulsions and Nano-particle Suspensions

Stability of thin liquid films containing surfactants, proteins, polymer latexes, or nano-particles is being investigated using reflected light microinterferometric techniques. These experiments have revealed for the first time the formation of "ordered" microstructures inside the film over distances of the order of one thousand Angstroms. This microstructure within the film is shown to provide a new mechanism for stabilizing dispersed phase systems. Monte Carlo and Molecular Dynamic simulations are conducted to verify the experimental observations. Important technological factors affecting the ordered microstructure formation and stability of colloidal dispersions such as foam, and emulsion and colloidal suspensions using nanoparticles are being investigated. The National Science Foundation, which is funding his research, awarded Dr. Wasan a special creativity award for this work and he was elected to the National Academy of Engineering, the highest professional honor for engineers, for his research accomplishments.

Wetting, Spreading and Adhesion of Nanofluids on Solid Surfaces

Mechanisms of wetting, spreading and adhesion of fluids containing nanoparticles such as surfactant micelles, proteins and macromolecules are found to be different than those from wetting of normal fluids. A new mechanism of detergency involving nanoparticles structuring phenomena is being investigated. This research has applications in cleaning of hard surfaces such as silicon wafers and soil remediation as well as in adhesion of living cells on solid surfaces and fabrication of nanostructured materials such as photonic crystals. This research was highlighted in his paper published in the journal Nature in 2003.

Film Rheology and its Applications

This research program involves the development and use of a novel experimental technique called film rheometry to measure both the dynamic film tension and film elasticity of surfactant, proteins and polymeric systems. Applications of these properties can be used to control dispersed phase systems such as polymer emulsion stabilization, coalescence of water-in-oil emulsions, foam stability, antifoaming, and thinning of films between bubbles or drops.

Environmental Technologies

Environmental research is conducted on the remediation of high-level and low-level nuclear wastes, which will be immobilized into glass. Major inorganic and organic chemicals in these wastes can cause foaming and gas entrainment problems that ultimately result in excessive shutdown and loss of attainment. The specific aim of this research, which is supported by the U.S. Department of Energy, is to develop a fundamental understanding of the physicochemical mechanisms that produce foaming and air-entrainment in the radioactive waste separation as immobilization process and to develop and test advanced antifoam/defoamimg rheology modifier agents.

Food Colloids

Many food formulations including beverages such as beer, cappuccino and milk coffee employ protein stabilized foams and emulsions. Our research in food colloids is directed towards using experimental techniques already available in our laboratory to study the foam and emulsion quality and stability under various conditions in a variety of food dispersions. This work is supported by a number of industrial organizations.


2007 - Foreign fellow of the Indian National Academy of Engineering

2004 - Elected member of the U.S. National Academy of Engineering, the highest honor for engineers

2005 - Recipient of the American Institute of Chemical Engineers Alpha Chi Sigma Award for Fundamental and Applied Research in Chemical Engineering

2000 - Recipient of the American Chemical Society National Award in Colloid and Surface Chemistry


Professor Wasan's research has resulted in six U.S. patents.


“Interfacial Transport Processes and Rheology,” (textbook with D. Edwards and H. Brenner), Butterworth-Heinemann - publisher, 558 pages, Boston, MA (1991).


"Spreading of Nanofluids on Solid" D.T. Wasan and A.D. Nikolov, Nature, 423: 156-159 (2003).

"New Vistas in Dispersion Science and Engineering" D.T. Wasan, A.D. Nikolov and D. Henderson, AIChE Journal, 49(3): 550-556(2003).

"Texture and Stability of Emulsions and Suspensions: Role of Oscillatory Structural Forces" D.T. Wasan, A.D. Nikolov and F. Aimetti, Adv. in Colloid and Interface Sci., 108-109, 187-195 (2004).

"Structural Transitions in Two-Dimensional Hard-Sphere Systems," S.C., Wu, D.T. Wasan and A.D. Nikolov Physical Review E, 71, 056112 [1-8] (2005).

“Shear-Induced Fat Particle Structure Variation and the Stability of Food Emulsions: I. Effects of Shear History, Shear Rate and Temperature” W. Xu, A. Nikolov, D.T. Wasan, J Food Eng, 66, 97-105 (2005).

“Shear-Induced Fat Particle Structure Variation and the Stability of Food Emulsions: II. Effects of Surfactants, Protein and Fat Substitute” W. Xu, A. Nikolov, D.T. Wasan, J Food Eng, 66, 107-116 (2005).

“Prediction of Bubble Size Distribution During Aeration of Food Products,” W. Jang, A. Nikolov, D.T. Wasan, K. Chen and B. Campbell, Ind. & Eng. Chem. Res. 44 (5) 1296-1308 (2005).

“In-Layer Structuring of Like-Charged Macroions in a Thin Film,” D. Henderson, A. Trokhymchuk, A., Nikolov, D. Wasan, Ind. Eng. Chem. Res. 44 (5), 1175-1180 (2005).

“Foaming and Antifoaming in a Gas-Liquid Finely Divided Particulate System” K. Vijayaraghavan, A. Nikolov, D. Wasan, B. Calloway, M. Stone, D. Lambert, J. Chin. Inst. Chem. Engrs. 26 (1) 37-41 (2005).

“Structural Transitions in Two-Dimensional Hard-Sphere Systems,” S.C. Wu, D.T. Wasan, A.D. Nikolov, Physical Review E, 71, 056112 [1-8] (2005).

“Colloidal Dispersions: Structure, Stability and Geometric Confinement,” D. Wasan, A. Nikolov, B. Moudgil, Powder Technology 153, 135-141 (2005).

“Effect of Protein on Texture of Food Emulsion under Steady Flow,” W. Jang, A. Nikolov, D.T. Wasan, K. Chen and B. Campbell, Ind & Eng Chem. Res, 44, 4855-4862 (2005).

“Computer Simulation of Macroion Layering in a Wedge Film,” A. Trokhymchuk, D. Henderson, A. Nikolov, D.T. Wasan, Langmuir 21 (22) 10240-10250 (2005).

“The Destabilization of Aerated Food Products,” W. Jang, A. Nikolov and D.T. Wasan, J. Food Eng.76, 256-260 (2006).

“Ring Formation and Emulsion Texture and Stability in a Food-Beverage System,” Kong, Y. Nikolov, A., Wasan, D., Ogawa, A., J Disp Sci Tech. 27, 579-585 (2006).

“Radioactive Waste Foams: Formation and Mitigation,” K. Vijayaraghavan, A. Nikolov, D. Wasan, B. Calloway, M. L. Crowder, M. Stone, Z.H. Quershi, J. Environ. Eng. 132, 7, 716-724 (2006).

“Foam Formation and Mitigation in a Three-Phase Gas-Liquid-Particulate System,” K. Vijayaraghavan, A. Nikolov, D.T. Wasan, Advances in Colloid Interface Science 123-126 p 49-61 (2006).

“Confinement-Induced Structural Forces in Colloidal Systems,” Henderson, D.J., Nikolov, A.D., Trokhymchuk, A., and Wasan, D.T. Encyclopedia of Surface and Colloid Science, Second Edition, Somasundaran, P., Ed., Taylor and Francis: New York, pp 1485-1494 (2006).

“Spreading of Water Drop Triggered by Surface Tension Gradient Created by Localized Addition of Surfactant,” Chengara, A. Nikolov, A. D. and Wasan D.T., Ind. Eng. Chem. Res. 46, 10 2987-2995 (2007).

“Foams and Emulsions: The Importance of Structural Forces,” D. Wasan and A. Nikolov, Aust. J. Chem., 60, 633-637 (2007).

“Sedimentation in Nano-Colloidal Dispersions: Effects of Collective Interactions and Particle Charge,” Vesaratchanon, S., Nikolov, A.D. and Wasan, D.T. Adv Colloid Interface Sci. 134-135, 268-278 (2007).

“Role of Collective Interactions in Self-assembly of Charged Particles at Liquid Interfaces,” S. Wu, A. Nikolov and D.T. Wasan, Can. J Chem. Eng., 85, 5, 562-569 (2007).

“Vertical Spreading of Aqueous Trisiloxane Solution Driven by Spontaneously Developing Surface Tension Gradient,” Chengara, A. Nikolov, A.D. and Wasan D.T. Ind. Eng. Chem. Res. 47(10), 3639-3644 (2008).

“Sedimentation of Concentrated Monodisperse Colloidal Suspensions: Role of Collective Particle Interaction Forces”, Vesaratchanon, J.S., Nikolov, A.D. and Wasan, D.T., J. Coll. Interface Sci. 322, 180-189 (2008).

“Understanding the Effects of Dispersant Addition to Slurry Rheology using Laser Scanning Confocal Microscopy,” White, T.L., Stone, M.E., Calloway, T.B., Brigmon, R.L., Eibling, R.E., Nikolov, A. and Wasan, D. Separation Sci and Tech. 43, 2859-2871 (2008).

“Thin Liquid Films Containing Micelles or Nanoparticles” Wasan, D.T. and Nikolov, A.D., Current Opinion in Colloid and Interface Science, 13, 128-133 (2008).

“Two-Dimensional Self-Assembly of Similarly Charged Granular Particles,” Wu, S.C., Wasan, D.T. and Nikolov, A.D., Ind. Eng. Chem. Res. (Published on Web, 10-03-2007) 47,15, 5005-5015 (2008).

“Particles Driven Up the Wall by Bursting Bubbles,” Nikolov, A.D. and Wasan, D.T., Langmuir 24, 9933-9936 (2008).

“Emulsion Texture and Stability: Role of Surfactant Micellar Interactions in the Presence of Proteins,” Kong, Y. Nikolov, A.., Wasan, D., and Ogawa, A, I&EC Res 47 (23) 9108-9114 (2008).

“Collective Particle Interactions in the Sedimentation of Charged Colloidal Suspensions,” Vesaratchanon, J.S., Nikolov, A.D. and Wasan, D.T. I&EC Res. 48,(1) 80-84 (2009).

“Mechanisms of the Assembly of Nano- and Micro-Particle Two-Dimensional Structures in a Wedge Film,” Alex D. Nikolov and Darsh Wasan, I&EC Res. 48, 5, 2320-2326 (2009).

“The Importance of Oscillatory Structural Forces in the Sedimentation of a Binary Hard-Sphere Colloidal Suspension,” Vesaratchanon, J.S., Nikolov, A.D., Wasan, D.T., and Henderson. D. I&EC Res. 48, 14, 6641-6651 (2009).

“Foamability of Liquid Particle Suspensions: A Modeling Study,” Vijayaraghavan, K., Nikolov, A.D., Wasan, D.T. and Henderson, D. I&EC Res. 48 (17), 8180-8185 (2009).

“Particle-Laden Foams,” Wasan, D.T. and Nikolov, A.D. Chinese American Chemical Society Communications 3 (2) 33-36 (2009).