Mixed Surfactant Water System Phase Behavior And Structural Characteristics

1. Phase Behavior and Structure Character of Tween 80/TX-100/Water SystemThe phase behavior of Tween 80/TX-100/H2O system is shown by the phase diagram. The Tween 80/TX-100/H2O system can form micelle region (L1), reverse micelle region (L2) and hexagonal liquid crystal (HEX).The micro-structures of the aggregates are studied by the methods of Rheometer, Isothermal Titration Calormetry (ITC), Small-Angle X-ray Diffraction (SAXD) and Differential Scanning Calorimetry (DSC). In micelle phase, the micelle behavior is Newtonian at small and intermediate shear rates then starts to be shear thinning at high shear rates. Samples with a higherη0 behave as shear thinning at a smaller shear rate andη0 increasing with the addition of Tween 80,loss modulus is always big than storage modulus, so the system is major in viscosity that like with the character of liquid solution. The viscosity of the system decreases with the increasing of temperature, and Newtonian flow behavior is become broader. In the isothermal titration microcalorimetric study, heat changes in the mixed micelles are between single Tween 80 and TX-100. In HEX phase, the structure of hexagonal liquid crystal is becoming looser with the increasing of water when the ratio of Tween 80 and TX-100 is a constant. However, when the content of water is a constant, mixed micelles array more and more tightly with the addition of TX-100 and it is more and more easier for water to enter into the micelle inside. The relaxation time is decreased with the increasing of TX-100 content. We studied the affect of temperature, the results show that the phase convert temperature is decreasing with the addition of TX-100, that proved by Differential Scanning Calorimetry, and the rheological behavior of HEX in high temperatue corresponde to that of micelle. The hexagonal liquid crystal phase boundary has poor resist shear stress than center Hex. Creep-recovery experiments show that the restoration of the structure has a minimum recovery timeλ0 when the system only have Tween 80 and water..2. Phase Behavior and Structure Character of SDS/Tween 80/Water SystemThe phase behavior of SDS/Tween 80/H2O system is shown by the phase diagram. The SDS/Tween 80/H2O system can form micelle region (L1), reverse micelle region (L2), hexagonal liquid crystal (H1) and hexagonal liquid crystal (H2). The micro-structures of the aggregates are studied by the methods of Rheometer, Isothermal Titration Calormetry (ITC), Dynamic Light Scattering (DLS) and Small-Angle X-ray Diffraction (SAXD). In micelle phase, samples with a higherη0 behave as shear thinning at a smaller shear rate andη0 increasing with the addition of Tween 80,loss modulus is always big than storage modulus that the system present as viscosity. The isothermal titration calormetry studies show that the mixed cmc of system is greatly decreased with a little adding of Tween 80 and it between the cmc of Tween 80 and the cmc of SDS, and near the cmc of Tween 80. The aggregates changes from spherical micelles to rod-like micelles with the increasing of Tween 80 content proved by dynamic light scattering. In the liquid crystal region (H1), the radius increased with the Tween 80 content and water content. Infiltrate ratio decrease with the increasing of Tween 80. Elastic modulus, viscous modulus, complex viscosity increased with the increasing of SDS content. In liquid crystal region (H2), the radius increased with the Tween 80 content and water content and relaxation time either. Elastic modulus, viscous modulus, complex viscosity decreased with the increasing of Tween 80 content.3. Phase Behavior and Structure Character of GDA/Brij 30/Water SystemThe phase behavior of GDA/Brij 30/H2O system is shown by the phase diagram. The GDA/Brij 30/H2O system can form micelle region(L) , lamellar liquid crystal(LLC) and hexagonal liquid crystal(HEX). The micro-structures of the aggregates are studied by the methods of Rheometer, Isothermal Titration Calormetry (ITC), Nuclear Magnetic Resonance (NMR) and Small-Angle X-ray Diffraction (SAXD). In the micellar region, the viscosity of the system increased with the content of GDA, but the viscosity increased with increasing of Brij 30 content in constant total surfactant concentration. It is suggested that the maximum viscosity is close to the two-phase region. The cmc decreased with the addition of Brij 30. In the HEX phase, the structure of hexagonal liquid crystal is becoming looser with the increasing of water when the ratio of GDA and Brij 30 is a constant. However, when the content of water is a constant, mixed micelles array more and more tightly with the addition of GDA and it is more and more difficult for water to enter into the micelle inside. The relaxation time is decreased with the increasing of Brij 30. In lamellar liquid crystal phase, layer spacing increased with an increasing the content of Brij 30 or an increasing water content. Elastic modulus and viscous modulus are decreased with the increasing of Brij 30 content. Complex viscosity is large than the steady-state viscosity in the entire frequency range of about an order of magnitude that present like solid viscoelastic character, and incompatible with the Cox-Merz rule.