Laboratoire de Rhéologie UMR 5520 Particulate Fluids Processing Centre Microscopic and Macroscopic Characterization of Aot / Iso-octane / Water Sheared Lyotropic Lamellar Phases Ph.D. Viva Voce Yann AUFFRET Ecole Doctorale I-MEP2: Mécanique des Fluides, Energétique et Procédés Université Joseph Fourier – Grenoble 1, France Department of Chemical and Biomolecular Engineering The University of Melbourne, Australia 16 th of December 2008

2 Presentation Outline I.Lyotropic Lamellar Phases II.Shear Induced Structural Evolution III. Non-Linear Viscoelastic Properties Yann Auffret

3 I. Lyotropic Lamellar Phases Self-Assembling Properties of Surfactants Yann Auffret Surfactant (AOT) Hydrocarbon chains Polar head Apolar solvent (Iso-octane) Polar Solvent (Water)

4 I. Lyotropic Lamellar Phases Yann Auffret Self-Assembling Properties of Surfactants vsvs lsls a0a0 ~1/3~1/2 ~1~1 ‘SDS-like’ ‘AOT-like’

5 I. Lyotropic Lamellar Phases (Tamamushi and Watanabe, Colloid & Polymer Science, 1980) SAXS patterns along a water dilution line ( ESRF – D2AM french CRG beamline) S0S1 S2 S3S4 S5S6S7 Lamellar Phases L1: Direct Micelles (oil-in-water droplets) 2L: Two Distinct Phases L2: Reverse Micelles (water-in-oil droplets) L+LC: Micelles and Liquid Crystal Coexistence LC (H): Hexagonal Liquid Crystal LC (D) Lamellar Liquid Crystal Yann Auffret Nanoscopic Structural Characterization

6 I. Lyotropic Lamellar Phases Yann Auffret Nanoscopic Structural Properties Membrane volume fraction:  =  /d d  q0q0  d (Å) l s ≈11Å

7 I. Lyotropic Lamellar Phases Proliferation and ‘alignment’ of topological defects with increasing water content (Warriner et al., Science, 1996.) Yann Auffret Microscopic Properties  =0.41  =0.32  =0.79 Circularly polarized light microscopy Light P A λ /4 sample

8 Yann Auffret I. Lyotropic Lamellar Phases Conclusion Nanoscopic scale: - Lamellar structures for  <0.8 -  = 24.1Å 35Å<d<91Å Microscopic scale: - Permanent topological defects for  <0.5

9 Yann Auffret II. Shear Induced Structural Evolution Transient and Steady Flow  =0.32 Defect Rich Lamellar Phase Complex transient regime then apparent steady state  =0.79 Defect Poor Lamellar Phase : Constant stress upon apllication of constant shear rate Newtonian apparent behavior  =0.4Pa.s (Auffret et al, Rheologica Acta, 2008.)

10 X-ray beam Shear cell r ω Sample Yann Auffret II. Shear Induced Structural Evolution Nanoscopic Scale  =0.32

11 Yann Auffret II. Shear Induced Structural Evolution Microscopic Scale  =0.32 ω r P+λ/4λ/4+A Shear cell

12 Yann Auffret II. Shear Induced Structural Evolution Microscopic Scale Apparent steady state textures Frank’s Theory: steady state (Larson and Mead, Liquid Crystals, 1992.)

13 Yann Auffret II. Shear Induced Structural Evolution Macroscopic Effects  =0.32 Strain-controlled rtrt Transition at a critical strain:  c

14 Yann Auffret II. Shear Induced Structural Evolution Conclusion Rheological behavior of the shear induced ‘phase’? Nanoscopic scale: - Shear induced formation of lamellar vesicles Microscopic scale: - Strain controlled macroscopic to microscopic texture transition Macroscopic scale: - Strain controlled transient regime

15 Yann Auffret III. Non-linear Viscoelastic Properties Controlled Rheometry? Invariant apparent steady shear rate with various surface roughnesses g=r.tan(  ) g min ~a g=R 2 -R 1 g>>a

16 Yann Auffret Steady State of Reference Creep StepsRecovery Steps Applied Stress  init T init TwTw Time (s) step 1step 2step 3 Unknown III. Non-linear Viscoelastic Properties

17 time Recovery step ‘Probing’ step Applied Stress (Pa)‏ T init preshear Yann Auffret Steady State of Reference III. Non-linear Viscoelastic Properties (C. Baravian and D. Quemada, Rheologica Acta, 1998.) (Auffret et al, Eur. Phys. J. E, to be published) Maxwell-Jeffrey Model Inertio-Elastic Response: G (Pa) T init (s)

18 Yann Auffret Solid to Fluid Transition Applied Stress T init TwTw Time (s)  init  app (Caton and Baravian, Rheol. Acta, 2008) ‘Fluid’ regime Ternary creep ‘Solid’ regime Primary creep Solid to fluid transition Secondary Creep Inertio-Elastic Response III. Non-linear Viscoelastic Properties

19 Yann Auffret Solid to Fluid Transition Apparent shear history dependent yield stress Viscoelastic properties controlled by (  init,T init,T w ) Reproducible results on shear history dependent materials Definition of a ‘true’ steady state of reference III. Non-linear Viscoelastic Properties

20 Yann Auffret Conclusion - Multi-scale characterization at rest Lamellar phases  =24.1Å for  <0.8 Permanent topological defects for  <0.5 - Shear induced transition in ‘defect rich’ lamellar phase Lamellar vesicles formation Macroscopic to microscopic defects Strain controlled process - Viscoelastic properties of shear-induced lamellar vesicle Steady state of reference Inertio-elastic response analysis Solid to fluid transition

21 Possible developments - Confinement effects on rheological properties - Systematic studies as a function of membrane volume fraction - origin of topological defects and quantification - Confinement of ‘macro-molecules’ in such systems Yann Auffret Conclusion

22 Yann Auffret Acknowledgement - I. Pignot-Paintrand, CERMAV, UPR5301, Grenoble - C. Rochas, Laboratoire de Spectrometrie physique, UMR 5588, Grenoble - H. Galliard, Laboratoire de Rhéologie, UMR5520, Grenoble - F. Caton, Laboratoire de Rhéologie, UMR5520, Grenoble - D. Roux, D.E Dunstan and N. El Kissi (Ph.D Advisors) Questions? Thank You for your attention ********** **********

23 I. Lyotropic Lamellar Phases X-ray Wave Anisotopic Lamellar Structures Scattered waves Scattering pattern Isotropic Structures X-ray Wave Scattered waves Scattering pattern d d Yann Auffret Nanoscopic Structural Characterization

24 I. Lyotropic Lamellar Phases Unpolarized white light source Linear polarizers θ=0° Plane polarized light Linear polarizers θ=90° Unpolarized white light source No light α=0 α Isoclines Extinction of all wavelengths for:  =0 or  =  /2 α Isochromes Extinction of a given wavelength for:  n.e=k. Yann Auffret A α P  n1n1 n2n2 e Microscopic Properties

25 I. Lyotropic Lamellar Phases Unpolarized white light source Linear polarizer θ=0° λ/4 waveplate θ=45° sampleλ/4 waveplate θ=-45° Linear Analyzer θ=90° Microscope or wide lens camera Without λ/4 waveplatesWith λ/4 waveplates Addition of λ/4 waveplates: α(t)≈ω.t with ω>>1 P A P A ω Yann Auffret Microscopic Properties

26 II. Shear Induced Structural Evolution Shear rheometry Yann Auffret Shear rate: Shear stress: Shear Viscosity: Usual Shear Cells Strain-controlled mode: - Constant applied angular velocity - Torque evolution Stress controlled mode: - Constant applied torque - Angular displacement evolution

27 Yann Auffret III. Non-linear Viscoelastic Properties Controlled Rheometry? 20Pa 40Pa Constant apparent shear rate for: g>>a Invariant apparent steady shear rate with various surface roughnesses g=r.tan(  ) g min ~a g=R 2 -R 1 g>>a

28 Yann Auffret Recovery Time Effects Applied Stress (Pa)‏ TwTw  init Inertial Coupling Analysis Tw=0sTw=9hours III. Non-linear Viscoelastic Properties