Lamellar-to-Onion Transition with
Increasing Temperature under Shear Flow
In Nonionic Surfactant Systems
Tadashi Kato
Department of ChemistryTokyo Metropolitan University
1
August 12, ISSP2010/SOFT

Coworkers:
Rheo-SALS and Rheo-SAXS
Yuriko Kosaka (Graduate Student)
Makiko Ito (Graduate Student)
Daijiro Sato (Graduate Student)
Phase Behaviors and Viscosity
Michiko Matsu-ura (Under Graduate Student)
Mari Okamoto (Under Graduate Student of Kitasato Univ.)
Kahoru Obara (Under Graduate Student of Kitasato
Univ.)
Dr. Youhei Kawabata (Assistant Professor)

Surfactant Self-Assemblies in Water
spherical
micellescylindrical
micelleshydro- hydrophobic philicgroup grouphexagonal phasebranched
micellesbilayersbuilding blocks

bicontinuous
cubic phasehigher-order
structures(lyotropic liquidlamellar phase crystals)

Surfactant Self-Assemblies in Waterhydro- hydrophobic philicgroup group2 - 5 nm5 - 50 nm

lamellar phaseEffects of Shear Flow on Structures of Surfactant
Lamellar Phase- small-angle light, X-ray, and neutron scattering studies • Lamellar→ Onion transition

O. Diat et al. J. Phys II France 3, 1427 (1993),.

• Sponge→lamellar transition

J. Yamamoto and H. Tanaka, Phys. Rev. Lett. 77, 4390 (1996).
L. Porcar et al. Langmuir 19, 10779 (2003).

• Multi-lamellar vesicle→unilamellar vesicle trransition
M. Bergmeier et al., J. Phys. Chem. B 102, 2837 (1998).

• Collapse of membranes

A. Al kahwaji et al., Phys. Rev. Lett. 84, 3073 (2000).
L. Porcar et al. Phys. Rev. Lett. 95, 078302 (2005).

• Formation of multi-lamellar cylinders as intermediate structures between lamellae and onions.
J. Zipfel et al., Europhys. Lett. 53, 335 (2001).

• Anomalous Decrease in Lamellar Spacing
T. Kato et al. Langmuir, 20, 3504 (2004).

Transition from Lamellar to Onion Phase by Shear Flow
O. Diat, D. Roux, and F. Nallet, J. Phys. II (France) 3, 1427 (1993).

shear

1 – 20 µm
5 – 20 nm“Onion phase”

Lamellar phase(All the space is filled bymultilamellar vesicles alone)

shear

Electron microscope image(T. Gulik-Krzywicki et al. Langmuir 12, 4668 (1996).)

104
103
102

Dynamic phase diagram
Ⅲ

101

Ⅱ

100
10-1

Ⅰ

D / µmshear rate /s-1

Transition from Lamellar to Onion Phase by Shear Flow

O. Diat, D. Roux, and F. Nallet,
J. Phys. II (France) 3, 1427 (1993),
Phys. Rev. E 51, 3296 (1995).
P. Sierro and D. Roux
Phys. Rev. Lett. 78, 1496 (1997).

10
100
surfactant volume %Onion size can becontrolled bychanging shear rate
1/(shear rate)1/2

Long-range order In
orientation above a
critical shear rateTransition from Lamellar to Onion Phase by Shear FlowExperiments
・SDS/Pentanol/Water/Decane (Diat et al.,1993)
・SDS/Pentanol/Water/Dodecane (Courbin et al.,2002)
・SDS/Octanol/Brine (Sierro and Roux, 1997)
・AOT/Brine (Bergenholtz & Wagner, 1996, Courbin & Panniza, 2004)
・TDMAO/hexanol/water (Escalante et al., 2000).
・C10E3/Water, C12E4/Water (Müller et al, 1999, Zipfel et al., 2001, Leeet al., 2001, Nettesheim et al., 2003)

Theories・O. Diat et al. J. Phys. II (France) 3, 1427 (1993),
・E.van der Linden et al, Langmuir 12, 3127 (1996)
・A.G. Zilman and R. Granek, Eur. Phys. J. B 11, 593 (1999).
・S. W. Marlow and P. D. Olmsted, Eur. Phys. J. E 8, 485 (2002).

Conditions necessary for onion formation andtransition mechanism remain still unclear. .

Typical Phase Behaviors of CnEm /Water Systems at Rest

Sponge(L3) phase

Temperature / ℃

CnEm : CnH2n+1(OC2H4)mOH
L2
逆ミセル
L2

W + L2Lα
W + L1

Micellar
L1
phase
H1

lamellar(Lα) phase

V1(1) Composed of only surfactant and water(2) No electrostatic interaction.
C12E5
wt(3) A variety of phases can be observed just bychanging temperature %→ Useful for studying transition mechanism
not only at rest but also under shear

bicontinuous
cubic (V1) phasehexagonal(H1) phaseLamellar-to-Onion Transition under Shear Flowin Nonionic Surfactant (CnEm ) Systems
C10E3 /water, C12E4 /water
・T. D. Le et al., Langmuir 17, 999(2001), Phys. Chem. Chem. Phys.
3, 1310 (2001).
・ C. Oliviero et al., Col. Surf. A
228, 85 (2003).

CnEm : CnH2n+1(OC2H4)mOH
C10E3 40 wt%

Lamellar-to-onion transition
with decreasing temperature
C16E7 /water
・Y. Kosaka et al., Langmuir, 26, 3835
(2010).

Lamellar-to-onion transition
with Increasing temperature

C16E7 (48wt%)

Outline of the Present Talk
1. Lamellar-to-onion Transition with increasing temperature
at a constant shear rate in C16E7/water System(1) Results of simultaneous measurements of・Shear stress / small-angle light scattering (Rheo-SALS)
・Shear stress / small-angle X-ray scattering (Rheo-SAXS)(2) Conditions necessary for the onion formation
・Temperature-shear rate diagram
・Temperature-concentration diagram(3) Transition mechanism based on rheo-SAXS experiments
2. Reentrant lamellar-onion transition with varying temperature
at a constant shear rate in C14E5/water System

Phase Diagram of C16E7 / D2O System at Rest1)

L1 + WLα

the fractionof defects
decreases

1) K. Minewaki, T. Kato, H. Yoshida, and M. Imai, Langmuir 17, 1864 (2001).

Apparatus for Rheo-SALS1)
He-Ne
laser

polarizer Torque meter beam stop analyzer

ND filter

Couette cell

top view

lens

CCD
cameraquartz stator vapor
seal

Hh

1mm

Depolarized scattering Vhlaserbeam sample quartz
rotor

Polarized scattering

1) T. Kato et al., Prog. Colloid Polym. Sci., 129, 9-15 (2004), J. Phys.
Condens. Matter 17, S2923 (2005).

Temperature Dependences of Shear Stressand Depolarized SALS Patterns (48 wt%)

1 s-1

1 s-1

Temperature Dependences of Shear Stressand Depolarized SALS Patterns (48 wt%)
3 s-1

3 s-1
1 s-1

1 s-1

Depolarized SALS from optically anisotropic spheres
Calculated patterns
D↔: direction of polarization
R.J.Samuels, J.Polymer Sci.,
9, 2165 (1971)

Isolated onions
D =13µm D =7 µm-20q / µm-1

2-20q / µm-1

2

Randomly close-packed onions

multilamellar
polymerspherulites vesicles(onions)＋ ＋ ＋
5µm＋ ＋ ＋＋ ＋ ＋ ＋
-20

q / µm-1

2

Temperature Dependences of Shear Stressand Depolarized SALS Patterns (48 wt%)
3 s-1

3 s-1
1 s-1

1 s-1

Temperature Dependences of Shear Stressand Depolarized SALS Patterns (48 wt%)
3 s-1

3 s-1
1 s-1
It is well known that the transition to the onion
accompanies significant increase in shear
1 s-1 stress.
But in this case such an increment is observed
when the temperature is increased !

Temperature Dependences of Shear Stressand Depolarized SALS Patterns (48 wt%)
3 s-1

3 s-1

Diameterof onionsat 3 s-1

The onion size increases
and size distribution
becomes narrow with T

Apparatus for Rheo-SAXS1)
radialx-ray
tangential
sample(gap: 1mm)

polycarbonate(thickness: 0.5 mm）

solvent trap
x-ray
cupperRheometer: TA Instruments AR550

25 mm1) T. Kato et al. Photon Factory Activity Report 2005 #23 Part B (2006).
Y. Kosaka, M. Ito, Y. Kawabata, and T. Kato, Langmuir, 26, 3835 (2010).

Apparatus for Rheo-SAXS
Radial configuration

X-ray
beam

neutral2-D
detectorflow

radialx-ray
tangential
sample(gap: 1mm)

polycarbonate(thickness: 0.5 mm）

solvent trap

neutralvelocity
gradient

x-ray
cupper

X-ray beam

Tangential configuration

25 mmTemperature Dependences of Shear Stress and
2-D SAXS Patterns at 3 s-1 (48wt%)
Radialbeam
neutral2-D
detectorflow

neutralvelocity
gradient
Tangential
beam

3 s-1

Outline of the Present Talk
1. Lamellar-to-onion Transition with increasing temperature
at a constant shear rate in C16E7/water System(1) Results of simultaneous measurements of・Shear stress / small-angle light scattering (Rheo-SALS)
・Shear stress / small-angle X-ray scattering (Rheo-SAXS)(2) Conditions necessary for the onion formation
・Temperature-shear rate diagram
・Temperature-concentration diagram(3) Transition mechanism based on rheo-SAXS experiments
2. Reentrant lamellar-onion transition with varying temperature
at a constant shear rate in C14E5/water SystemTemperature Dependencesof Shear Stress (48wt%)

Temperature - Shear
Rate Diagram (48wt%)

onionsTransition region

lamellae
The transition temperaturedoes not depend on shear
rate very much.

Comparison with Other Homologous Systems
C10E3 40 wt%

Lamellar-to-onion transition
with decreasing temperature
T. D. Le et al., Langmuir 17,
999 (2001), C. Oliviero et al.,Col. Surf. A 228, 85 (2003).

Temperature dependenceof elastic properties ofisolated membranes
C16E7 (48wt%)

Lamellar-to-onion transition
with increasing temperature
Y. Kosaka et al., Langmuir,
26, 3835 (2010).
25

Elastic Properties of Isolated Membranes
Elastic free energy of bilayer relative to a flat state (Lα)

L3 phase: bending modulus of a bilayer: saddle splay modulus of a bilayer

L3
A vesicle of radius R

0

Lα
v

W. Helfrich, J. Phys. Condens.
Matter 6, A79 (1994).

Elastic Properties of Isolated Membranes
Saddle splay modulus of a bilayer

L3
decrease of T

: saddle splay modulus of a monolayer 0
H0m : spontaneous curvature of a monolayerδ hc: thickness of a hydrophobic part of amonolayer

LαNonionic surfactants of the CnEm type
→ H0m increases with decreasing T 1)→
decreases with decreasing T 2)
→ Vesicles become more stable than lamellae inthe lower temperature range 2)
1) R. Strey, Colloid Polym. Sci. 272, 1005 (1994).
2) T. D. Le et al. Langmuir 17, 999 (2001).

v

Comparison with Other Homologous Systems
C10E3 40 wt%
C. Oliviero et al.,Col. Surf. A, 85,
228 (2003))

C16E7 (48wt%)
Kosaka et al.,Langmuir (2010).

L3○

decrease of T

×

0

Lα
v
: bending modulus ofa bilayer: saddle splay modulus
of a bilayer

Our results cannot be
explained by properties ofisolated membranes
The transition should bedominated by other factors

Outline of the Present Talk
1. Lamellar-to-onion Transition with increasing temperature
at a constant shear rate in C16E7/water System(1) Results of simultaneous measurements of・Shear stress / small-angle light scattering (Rheo-SALS)
・Shear stress / small-angle X-ray scattering (Rheo-SAXS)(2) Conditions necessary for the onion formation
・Temperature-shear rate diagram
・Temperature-concentration diagram(3) Transition mechanism based on rheo-SAXS experiments
2. Reentrant lamellar-onion transition with varying temperature
at a constant shear rate in C14E5/water System

Phase Behaviors of C16E7 / D2O System at Rest1) andthe Lamellar-to-Onion Transition Temperature at 3 s-1

48 wt%

1) K. Minewaki, T. Kato, H. Yoshida, and M. Imai, Langmuir 17, 1864 (2001).

Phase Behaviors of C16E7 / D2O System at Rest1) andthe Lamellar-to-Onion Transition Temperature at 3 s-1

40 48 51 55 wt%

The transition temperature increases
with increasing surfactant concentration
1) K. Minewaki, T. Kato, H. Yoshida, and M. Imai, Langmuir 17, 1864 (2001).

SAXS Study on the Lamellar Phase of C16E7
System at Rest1)

d δ

hc

δeo
electron density
32 wt%
55 wt%
・ exp.
 fit

P(q): form factor of bilayers*↔ δhc, δeo
S(q): structure factor*↔ d, η
η ⇔ fluctuations of d
* F. Nallet, R. Laversanne, and D. Roux,
J. Phys. II France, 3, 487 (1993)(applied to AOT-water and DDAB-water)

1) K. Minewaki, T. Kato, H. Yoshida, and M. Imai, Langmuir 17, 1864 (2001).

Comparison with Temperature Dependence ofRepeat Distance at Rest1)
40 wt%
40 48 51 55 wt%

d δ
48 wt%
51 wt%
55 wt%

δ1) K. Minewaki, T. Kato, H. Yoshida, and M. Imai, Langmuir 17, 1864 (2001).

Comparison with Temperature Dependence ofRepeat Distance at Rest1)
40 wt%
40 48 51 55 wt%

d δ
48 wt%
51 wt%
55 wt%

1) K. Minewaki, T. Kato, H. Yoshida, and M. Imai, Langmuir 17, 1864 (2001).

Comparison with Temperature Dependence ofRepeat Distance at Rest1)
40 wt%
40 48 51 55 wt%

d δ
48 wt%
51 wt%
55 wt%

Onions can be formed only when
the ratio d/δ exceeds a certain
critical value
Increase in the repeat distance at
rest may be necessary for thetransition
1) K. Minewaki, T. Kato, H. Yoshida,
and M. Imai, Langmuir 17, 1864 (2001).

Comparison with Other Homologous Systems
C10E3 40 wt%
C. Oliviero et al.,Col. Surf. A, 85,
228 (2003))

Lamellar-to-onion transition
with decreasing temperature
Decrease in the saddle splay
modulus of a bilayer withdecreasing temperature ?

C16E7 (48wt%)
Kosaka et al.,Langmuir (2010).

Lamellar-to-onion transition
with increasing temperature
Increase in the repeat
distance with increasing
temperature at restOutline of the Present Talk
1. Lamellar-to-onion Transition with increasing temperature
at a constant shear rate in C16E7/water System(1) Results of simultaneous measurements of・Shear stress / small-angle light scattering (Rheo-SALS)
・Shear stress / small-angle X-ray scattering (Rheo-SAXS)(2) Conditions necessary for the onion formation
・Temperature-shear rate diagram
・Temperature-concentration diagram(3) Transition mechanism based on rheo-SAXS experiments
2. Reentrant lamellar-onion transition with varying temperature
at a constant shear rate in C14E5/water SystemTemperature Dependences of Shear Stress and
2-D SAXS Patterns at 3 s-1 (48wt%)
Radialbeam
neutral2-D
detectorflow

neutralvelocity
gradient
Tangential
beam

3 s-1

Temperature Dependences of Shear Stress and
2-D SAXS Patterns at 3 s-1 (48wt%)

3 s-1
0.5 K /15 minTemperature Dependences of Shear Stress and
2-D SAXS Patterns at 3 s-1 (48wt%)
3 s-1

0.1 K /15 min

0.1 K /15 min

3 s-1
0.5 K /15 min40Temperature Dependences of Shear Stress and
2-D SAXS Patterns at 3 s-1 (48wt%)

3 s-1

0.1 K /15 minTemperature Dependences of Shear Stress and
2-D SAXS Patterns at 3 s-1 (48wt%)
Radialbeam
neutral2-D
detectorflow

neutralvelocity
gradient
Tangential
beam

3 s-1
0.1 K /15 min
42Temperature Dependence of
SAXS Peak Intensity

gradient
gradient
neutralflow

neutralflow

Temperature Dependence of
SAXS Peak Intensity

gradient
neutralgradient

flow

neutralflow

velocity
gradientflowTemperature Dependence of
SAXS Peak Intensity
The orientation of lamellae tothe velocity gradient direction
is suddenly enhanced
gradient
neutralgradient

flow

neutralflow

velocity
gradientflow

45

Temperature Dependence of
SAXS Peak Intensity

gradient
neutralgradient

flow

neutralflow

velocity
gradientflow

46

Temperature Dependence of
SAXS Peak Intensity

gradient(× 0.1)
gradient
neutralneutral

flow

flow

velocity
gradientflow

47

Temperature Dependence of
SAXS Peak Intensity

gradient
neutralgradient

flow

neutralflow

velocity
gradientflow

48

Theory for Onion Formation
A.G. Zilman and R. Granek Eur. Phys. J. B 11, 593 (1999).
Top view
flow
gradient

Coupling with the shear
flow of short wavelength
undulation mode
→ effective force acting to
reduce the excess area〜µm
coherent buckling
Deformation of thein µm scale
buckling structure

neutralgradient

Side viewη ∼ 10-3 Pa s κ ∼ kBT
d ∼ 10 nm D ∼ 1mm

Theory itself
may be wrong

Temperature Dependence of
SAXS Peak Intensity
The orientation of lamellae tothe velocity gradient direction
is suddenly enhanced
Consistent with
our results
coherent
buckling1)

gradient
neutralgradient

flow

neutralflow

1) A.G. Zilman and R. Granek
Eur. Phys. J. B 11, 593 (1999).

velocity
gradientflow

50

C10E3 at 25℃ at 10 s-1 (SANS)
neutralflow
gradient
gradient

neutralviscosity

flow

Transition coordinate
F. Nettesheim, J. Zipfel, U. Olsson, F.
Renth, P. Linder, and W. Richtering,Langmuir, 19, 3618 (2003).

C10E3 at 25℃ at 10 s-1

C16E7 at 3 s-1
gradient(× 0.1)

neutralflow

neutralflow

gradient
gradient

neutralviscosity

gradient
neutralflow

flow

Transition coordinate
F. Nettesheim, J. Zipfel, U. Olsson, F.
Renth, P. Linder, and W. Richtering,Langmuir, 19, 3618 (2003).

Outline of the Present Talk
1. Lamellar-to-onion Transition with increasing temperature
at a constant shear rate in C16E7/water System(1) Results of simultaneous measurements of・Shear stress / small-angle light scattering (Rheo-SALS)
・Shear stress / small-angle X-ray scattering (Rheo-SAXS)(2) Conditions necessary for the onion formation
・Temperature-shear rate diagram
・Temperature-concentration diagram(3) Transition mechanism based on rheo-SAXS experiments
2. Reentrant lamellar-onion transition with varying temperature
at a constant shear rate in C14E5/water System

Comparison with Other Homologous Systems
C10E3 under shear(40 wt%)C. Oliviero et al.,Col. Surf. A, 85,
228 (2003))

C16E7

under shear(48wt%)

Kosaka et al.,Langmuir (2010).

Lamellar-to-onion transition
with decreasing temperature
Decrease in the saddle
splay modulus of a bilayer

Is there any system
which exhibits bothtypes of transition ?
Lamellar-to-onion transition
with increasing temperature
Increase in the repeat
distance at rest

Comparison with Phase Behaviors at Rest
C10E3 under shear(40 wt%)C. Oliviero et al.,Col. Surf. A, 85,
228 (2003))

at rest

Le et al., Langmuir (2001)
W + L2

L2

L3
Lα

C16E7

lamellar(Lα) phaseat restunder shear(48wt%)

Kosaka et al.,Langmuir (2010).

Minewaki et al., Langmuir(2001)

bicontinuous
cubic (V1) phase
W + L1hexagonal(H1) phaseComparison with Phase Behaviors at Rest
C10E3 under shear(40 wt%)C. Oliviero et al.,Col. Surf. A, 85,
228 (2003))

at rest

Le et al., Langmuir (2001)
W + L2

L2

L3
Lα

C16E7

lamellar(Lα) phaseat restunder shear(48wt%)

Kosaka et al.,Langmuir (2010).

Minewaki et al., Langmuir(2001)

bicontinuous
cubic (V1) phase
W + L1

We should look for a systemhaving the lamellar phase in amore wide temperature range

hexagonal(H1) phasePhase Behaviors at Rest
C10E3 /watertemperature / ℃

100
80

C12E5 / water
W + L2

60

0

2

L3
Lα

Lα

40
20

L2
L2
逆ミセル

Le et al., Langmuir (2001)
W + L2
L

L1

V1

lamellar(Lα) phase

C16E7 /water

Minewaki et al., Langmuir (2001)

H1
W + L1bicontinuous
cubic (V1) phase

C12E5 wt %CnEm : CnH2n+1(OC2H4)mOH

hexagonal(H1) phaseTemperature - Concentration Diagrams at 3 s-1
C16E7 / water

C16E6 / water

CnEm : CnH2n+1(OC2H4)mOH

C14E5 / waterTemperature Dependence of Shear Stress and 2-D
SAXS Patterns for C14E5 /Water System at 3 s-1

Shear stress

Lamellar-onion-lamellartransition (Reentrant
lamellar-onion transition)with varying temperatureTemperature Dependence of Shear Stress and 2-D
SAXS Patterns for C14E5 /Water System at 3 s-1

Shear stress

Lamellar-onion-lamellartransition (Reentrant
lamellar-onion transition)with varying temperatureTemperature Dependence of Shear Stress and 2-D
SAXS Patterns for C14E5 /Water System at 3 s-1

Shear stress

Lamellar-onion-lamellartransition (Reentrant
lamellar-onion transition)with varying temperatureTemperature Dependence of Shear Stress and 2-D
SAXS Patterns for C14E5 /Water System at 3 s-1

Shear stress

Lamellar-onion-lamellartransition (Reentrant lamellaronion transition) with varying
temperature

Closed region of the onion phase !
Useful system for clarifying
mechanism of onion formation

Temperature Dependence of Shear Stress and 2-D
SAXS Patterns for C14E5 /Water System at 3 s-1
Upper transition⇔ Change in saddle splay modulus?

Shear stress
There has been no theory
taking into
account both saddle splay modulus
and repeat distance under shear

Repeatdistance at rest
Lower transition⇔ Change in repeat distance at rest (d)Theory for Stable Equilibrium Onion Phase
L. Ramos et al., Europhys. Lett. 66, 888 (2004).

Free energy of a symmetric bilayer(relative to a flat state)

A vesicle of radius r

Condition for the
stable onion phasevolume fractionof bilayers

δ : thickess of a bilayer→ Minimized overkmax
Apollonian distribution

Theory for Stable Equilibrium Onion Phase (at Rest) 1)
and Reentrant Lamellar/Onion Transition under Shear
1) L. Ramos et al., Europhys. Lett. 66, 888 (2004).

: bending modulus of a bilayer: saddle splay modulus of a bilayer

Condition for the
stable onion phasevolume fractionof bilayers

δ : thickess of a bilayer: saddle splay modulus of a monolayer
H0m : spontaneous curvature of a monolayerδ hc: thickness of a hydrophobic part of amonolayer

CnEm systems:
T↓ ⇔

↑ ⇔

↓ ⇔

↑

CnEm systems:↑⇔T↓Theory for Stable Equilibrium Onion Phase (at Rest) 1)
and Reentrant Lamellar/Onion Transition under Shear
1) L. Ramos et al., Europhys. Lett. 66, 888 (2004).

Condition for the
stable onion phasevolume fractionof bilayers

The repeat
distance at rest(d) increases
with temperatureδ : thickess of a bilayer

CnEm systems:↑⇔T↓Theory for Stable Equilibrium Onion Phase (at Rest)and Reentrant Lamellar/Onion Transition under Shear← L. Ramos et al. (2004)
δ : thickness ofa bilayer: bending modulus ofa bilayer: saddle spray
modulus of a bilayer

Temperature dependenceof -(δ/d)2 for C14E5 systemc’: numerical factorof order 1
CnEm systems:↓⇔T↓Theory for Stable Equilibrium Onion Phase (at Rest)and Reentrant Lamellar/Onion Transition under Shear: bending modulus ofa bilayer: saddle spray
modulus of a bilayer

Temperature dependenceof -(δ/d)2 for C14E5 system

Theory for Stable Equilibrium Onion Phase (at Rest)and Reentrant Lamellar/Onion Transition under Shear: bending modulus ofa bilayer: saddle spray
modulus of a bilayer

Temperature dependenceof -(δ/d)2 for C14E5 system

Summary
1.Lamellar-to-onion transition with increasing
temperature has been found at a constantshear rate in nonionic surfactant C16E7/
water system by using Rheo-SALS and
Rheo-SAXS.
2. Increase in the repeat distanceat rest is necessary for thedδlamellar-to-onion transition withincreasing temperature.
3. The orientation of lamellae along
the velocity gradient direction issuddenly enhanced just before
the transition.
4. Reentrant lamellar-onion transition
has been found in C14E5/water
system. This system is considered
to be useful to study the conditions
flow
and mechanism of onion formation.