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Understanding Surfactants: Their Interactions, Applications, and Microemulsion Dynamics

This study explores surfactants and their critical role in various applications, including personal care, cosmetics, and enhanced oil recovery. We investigate the complex interactions such as Coulomb, Van der Waals, and hydrogen bonds among surfactant molecules. The work also delves into microemulsion systems, examining film formation from bulky surfactants, packing parameters, and phase behavior at micro and macroscopic scales. Experimental techniques, including rheology, NMR, and small-angle scattering, are utilized to elucidate the properties and stability of these surfactant-based systems.

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Understanding Surfactants: Their Interactions, Applications, and Microemulsion Dynamics

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  1. SANS atinterfacesand in bulksystemsundershear Henrich Frielinghaus JCNS c/o TUM, 85747 Garching

  2. Surfactants Ionic // Coulomb Van Der Vaals Hydrogen Bonds Teflon / FlourinatedCarbonMolecules

  3. Applications of Surfactants Hair care Personal care Cosmetics Detergents Enhanced oil recovery

  4. MacroscopicVolumes CMC water

  5. Packing Parameter cone wedge cylinder P = 0 .. 1/3, 1/3 .. 1/2, 1/2 .. 1, 1

  6. Symmetry: Entropy: Finite Length Finite Area Shape CurvatureUndulationsUndulations

  7. L3 Lα H1

  8. Interactions StericRepulsions Coulomb Interactions Symmetry: Cubic, hexagonal, lamellar… Entropy: Distortions Soft Matter ClassicalHard Matter Soft Potentials Coulomb Potentials High Entropy Low Entropy

  9. Microemulsions Stability !!! Water:H2OOil:Decane Surfactant:C10E4 Micelles Film Water Oil

  10. BicontinuousMicroemulsion 1µm

  11. Larson

  12. Free Energy R1 c1 = R1-1 c2 = R2-1 R2

  13. Phase Diagram f. Small Concentrations γ-1

  14. Interactions

  15. OilSurfactantWater

  16. TranslationalEntropy N: latticesites k: species A N-k: species B

  17. Summary: Microemulsions FromBulkySurfactantMolecules Surfactant Film * Packing Parameter * Helfrich Energy Simple Shapes (dilutedsystem) Liquid CrystallinePhases

  18. Measurements

  19. Rheology Optical Measurements CrossedPolarizers Anisotropic Domains

  20. NMR - Microemulsion

  21. Detector Collimation Incident Beam Θ Monochromator Sample Intensity Small Angle Scattering:

  22. SAS PS-PI PEO-PB

  23. Formfactors

  24. TEM

  25. SummaryMeasurements • Optical • NMR • Rheology • Relative Viscosities • Frequencysweep • Small Angle Scattering • Formanypeaks: High accuracy • Forindistinguishablepeaks: Esoteric • TEM • Manycutsneeded isotropic / anisotropic quick and easy powerful (singlecrystals) … furtherextension

  26. Scatteringfrompolymericsystems WormlikeMicelles Polymer Micelles

  27. PEP1-PEO1 PEP10-PEO10and PEP22-PEO22

  28. WormlikeMicellesor Polymer PS in CS2 water/isooctane/lecitin

  29. OilProduction • Aqueous Surfactant Systems are used for: • Drilling Fluid • Secondary/Tertiary Oil Production • Fracturing Fluid

  30. Simulations (M. Belushkin) Single order parameter: +1: Oil -1: Water 0: Surfactant Lamellar order decays !!!

  31. The System Water: D2O, H2O (41.5%vol) Oil: Decane (41.5%vol) Surfactant: C10E4 (17.0%vol) Temperature ca. 25°C The Cell 15 cm n Silicon 2 cm 0.1° Cd Cd 0.5 mm Glass with Boron

  32. The Cell

  33. Grazingincidence:  Reflect.: 1 µm < ζ// < 20 µm GISANS: 2 nm < ζ// < 600 nm (large y, critical angle) might be large...

  34. Evanescent Wave: the depth information

  35. Measurements vs. Fits

  36. Resultsfrom GISANS Lamellar: Peak Isotropic: perforated lam. + bicontinuous

  37. n n

  38. Microemulsion with Unsymmetric Polymer WATER

  39. Shear Scans with SANS hexagonal

  40. Comparison to Injected Microemulsion in GISANS Cell shear No Alingnment Perfect Alignment Lamellar Order Near Surface

  41. Comparison to Injected Microemulsion in GISANS Cell shear Silicon

  42. Summary Amphiphile Condensation – SelfAssembly High Symmetry Interactions Concepts:* AqueousSurfactant Systems * Microemulsions * (Polymeric Systems) not here * (MesoscopicParticles) (Ianus) not here Actualresearch: Surfaces MesoscopicParticles Surfactants+Polymers

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