COLL 6 |
| Jeffrey H. Harwell1, Edgar Acosta2, Erika Szekeres2, and David A Sabatini3. (1) College of Engineering, University of Oklahoma, 202 W. Boyd, Carson Engineering Center, Room 107, Norman, OK 73019, (2) School of Chemical Engineering and Materials Science, University of Oklahoma, 100 East Boyd Street, Sarkleys Energy Center, Room T-335, Norman, OK 73019, (3) Institute of Applied Surfactant Research, University of Oklahoma, 100 East Boyd Street, Sarkeys Energy Center, Room T-335, Norman, OK 73019 |
| Critical scaling theory is used to describe Winsor Type I, II, III and IV microemulsions, including droplet sizes, interfacial tensions, and phase diagrams. Five assumptions are made: (1) The model’s critical point is the microemulsion’s “optimum formulation.” (2) Salager’s Surfactant Affinity Difference (SAD) expression gives dimensionless chemical potential differences. (3) The critical scaling exponent is “1” by analogy with the Kelvin capillary equation. (4) The net-average curvature of coexistent fictitious oil and water droplets provides a statistical description of the interfacial curvature in bicontinuous microemulsions. (5) A Helfrich/DeGennes interfacial rigidity expression accounts for the interfacial tension. The model requires only two adjustable parameters, the scaling length (L, approximately the extended length of the surfactant tail) and the rigidity of the surfactant-saturated interface (Er, always close to KBT), yet it accurately describes not only Type I, II and III droplet-microemulsion, but also bicontinuous microemulsions. |
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ACS Award in Colloid and Surface Chemistry Symposium Honoring Clay Radke
Division of Colloid and Surface Chemistry |