SANS at interfaces

daughterduckUrban and Civil

Nov 15, 2013 (3 years and 8 months ago)

108 views

SANS
at

interfaces

and

in
bulk

systems

under

shear


Henrich Frielinghaus


JCNS 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

L
3

L
α

H
1

Symmetry
:

Cubic
, hexagonal, lamellar…

Entropy
:

Distortions

Soft Matter


Classical

Hard

Matter

Soft Potentials


Coulomb Potentials

High
Entropy


Low
Entropy

Interactions

Steric

Repulsions

Coulomb Interactions

Microemulsions

Water:

H
2
O



Oil:

Decane


Surfactant:

C
10
E
4

H
O
H
O
O
O
O
O
H
Film

Water

Oil

Micelles

Stability

!!!

1µm

Bicontinuous

Microemulsion

Larson

Free
Energy

R
1

R
2

c
1

= R
1
-
1

c
2

= R
2
-
1

γ
-
1

Phase
Diagram

f. Small
Concentrations

Interactions

Oil

Surfactant

Water

Translational

Entropy

N:
lattice

sites


k:
species

A

N
-
k:
species

B

B
B
A
A
B
k
N
k
N
k
S




ln
ln
)!
(
!
!
ln
)
ln(



















Summary
:
Microemulsions

From

Bulky

Surfactant

Molecules



Surfactant

Film


*
Packing

Parameter * Helfrich
Energy


Simple Shapes (
diluted

system
)

Liquid
Crystalline

Phases

Measurements

Optical
Measurements

Crossed

Polarizers


Anisotropic

Domains

Rheology

10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
-2
10
-1
10
0
Bicontinuous
at 32.0
o
C
Hexagonal
at 25.5
o
C
Cubic
at 21.5
o
C


Viscosity [Pa

s]
Shear Rate [1/s]
NMR
-

Microemulsion

Small Angle
Scattering
:









2
)
2
sin(
4
Q


2

Q
Monochromator

Collimation

Incident

Beam

Sample

Θ

Detector

Intensity

SAS

PEO
-
PB

PS
-
PI

Formfactors

TEM

Summary

Measurements

Optical


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

PEP
10
-
PEO
10

and

PEP
22
-
PEO
22

PEP
1
-
PEO
1

PS in CS
2

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: D
2
O, H
2
O (41.5%vol)

Oil: Decane (41.5%vol)

Surfactant: C
10
E
4

(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




























f
i
y
y
f
i
z
y
x
q
q
q








2
2
1
2
2
2
1
)
(
2
Grazing

incidence
:

Evanescent Wave:

the depth information

2
1
0
,




i
L
Measurements

vs.
Fits

Results

from

GISANS

Lamellar: Peak


Isotropic: perforated lam.


+

bicontinuous

n

n

Microemulsion with Unsymmetric Polymer

WATER



10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
-2
10
-1
10
0
Bicontinuous
at 32.0
o
C
Hexagonal
at 25.5
o
C
Cubic
at 21.5
o
C


Viscosity [Pa

s]
Shear Rate [1/s]
Shear Scans with SANS
hexagonal

10
-2
10
-1
10
0
10
1
10
2
10
3
10
4
10
-2
10
-1
10
0
Bicontinuous
at 32.0
o
C
Hexagonal
at 25.5
o
C
Cubic
at 21.5
o
C


Viscosity [Pa

s]
Shear Rate [1/s]
Comparison to Injected Microemulsion in GISANS Cell

Perfect Alignment

No Alingnment

Lamellar Order

Near Surface

shear

Comparison to Injected Microemulsion in GISANS Cell

shear

Silicon

0.01
100
1000
hexagonal at 100 s
-1
flow (horizontal)
neutral (vertical)


d

/d

[cm
-1
]
Q [
Å
]
Summary

Amphiphile

Condensation



Self

Assembly

High
Symmetry

Interactions

Concepts
:

*
Aqueous

Surfactant

Systems


*
Microemulsions


* (
Polymeric

Systems)
not
here


* (
Mesoscopic

Particles
) (
Ianus
)
not
here


Actual

research
:

Surfaces

Mesoscopic

Particles

Surfactants

+

Polymers