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SANS at interfaces and in bulk systems under shear Henrich Frielinghaus JCNS c/o TUM, 85747 Garching. Surfactants. Ionic // Coulomb. Van Der Vaals. Hydrogen Bonds. Teflon / Flourinated Carbon Molecules. Applications of Surfactants. Hair care. Personal care. Cosmetics. - PowerPoint PPT Presentation
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SANS at interfaces and in bulk systems under shear
Henrich FrielinghausJCNS c/o TUM, 85747 Garching
Hydrogen Bonds
Ionic // Coulomb
Van Der Vaals
Teflon / Flourinated Carbon Molecules
Surfactants
Detergents
Hair care
Enhanced oil recovery
Cosmetics
Personal care
Applications of Surfactants
CMC
Macroscopic Volumes
water
cone wedge cylinder
P = 0 .. 1/3, 1/3 .. 1/2, 1/2 .. 1, 1
Packing Parameter
Symmetry:
Entropy: Finite Length Finite Area
Shape Curvature Undulations Undulations
L3
Lα
H1
Symmetry: Cubic, hexagonal, lamellar…
Entropy:Distortions
Soft Matter Classical Hard Matter
Soft Potentials Coulomb Potentials
High Entropy Low Entropy
InteractionsSteric RepulsionsCoulomb Interactions
Microemulsions
Water: H2O Oil: Decane
Surfactant: C10E4
HOH
OO
OO
OH
FilmWater Oil
Micelles
Stability !!!
1µm
Bicontinuous Microemulsion
Larson
Free Energy
R1
R2
c1 = R1-1
c2 = R2-1
γ-1
Phase Diagram f. Small Concentrations
Interactions
Oil Surfactant Water
Translational Entropy
N: lattice sites
k: species AN-k: species B
BBAAB kNk
NkS lnln
)!(!!ln)ln(
Summary: Microemulsions
From Bulky Surfactant Molecules Surfactant Film
* Packing Parameter * Helfrich Energy
Simple Shapes (diluted system)
Liquid Crystalline Phases
Measurements
Optical MeasurementsCrossed Polarizers
Anisotropic Domains
Rheology
10-2 10-1 100 101 102 103 10410-2
10-1
100
Bicontinuous at 32.0oC
Cubic at 21.5oC
Vis
cosi
ty [P
as]
Shear Rate [1/s]
NMR - Microemulsion
Small Angle Scattering:
2)
2sin(4Q
2
Q
Monochromator
CollimationIncidentBeam
Sample
Θ
Detector
Intensity
SAS
PEO-PB PS-PI
Formfactors
TEM
Summary MeasurementsOptical
NMR
Rheology• Relative Viscosities• Frequency sweep
Small Angle Scattering• For many peaks: High accuracy• For indistinguishable peaks: Esoteric
TEM• Many cuts needed
isotropic / anisotropic
quick and easy
powerful(single crystals)
further extension…
Scattering from polymeric systems
Polymer Micelles
Wormlike Micelles
PEP10-PEO10 and PEP22-PEO22PEP1-PEO1
PS in CS2 water/isooctane/lecitin
Wormlike Micelles or Polymer
Oil Production
Aqueous Surfactant Systems are used for:• Drilling Fluid• Secondary/Tertiary Oil Production• Fracturing Fluid
Simulations (M. Belushkin)
Single order parameter:
+1: Oil -1: Water 0: Surfactant
Lamellar order decays !!!
The System
The Cell
Water: D2O, H2O (41.5%vol)Oil: Decane (41.5%vol)Surfactant: C10E4 (17.0%vol)
Temperature ca. 25°C
Silicon
Cd
Glass with Boron
Cd 0.5 mm
2 cm
15 cm
0.1°
n
The Cell
GISANS: 2 nm < ζ// < 600 nm
(large y, critical angle) might be large...
Reflect.: 1 µm < ζ// < 20 µm
fi
y
yfi
z
y
x
qqq
22122
21 )(
2
Grazing incidence:
Evanescent Wave: the depth information
21
0, iL
Measurements vs. Fits
Results from GISANS
Lamellar: Peak
Isotropic: perforated lam. + bicontinuous
n n
Microemulsion with Unsymmetric Polymer
WATER
10-2 10-1 100 101 102 103 10410-2
10-1
100
Bicontinuous at 32.0oC
Hexagonal at 25.5 oC
Cubic at 21.5oC
Vis
cosi
ty [P
as]
Shear Rate [1/s]
Shear Scans with SANS hexagonal
10-2 10-1 100 101 102 103 10410-2
10-1
100
Bicontinuous at 32.0oC
Hexagonal at 25.5 oC
Cubic at 21.5oC
Vis
cosi
ty [P
as]
Shear Rate [1/s]
Comparison to Injected Microemulsion in GISANS Cell
Perfect Alignment
No Alingnment
Lamellar OrderNear Surface
shear
Comparison to Injected Microemulsion in GISANS Cellshear
Silicon
0.01
100
1000
hexagonal at 100 s-1
flow (horizontal) neutral (vertical)
d/d
[cm
-1]
Q [Å]
SummaryAmphiphileCondensation – Self AssemblyHigh SymmetryInteractions
Concepts: * Aqueous Surfactant Systems * Microemulsions * (Polymeric Systems) not here
* (Mesoscopic Particles) (Ianus) not here
Actual research:SurfacesMesoscopic ParticlesSurfactants + Polymers
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