Study On Phase Behavior And Rheological Performance Of Cationic Surfactant-PVA System

Surfactant molecules have amphiphilic structure which enables them to self assemble into micelle,liquid crystal and other association structures in solution and forming different phase.Generally,the phase of the system can be changed by simply adjusting the concentration of surfactant and the proportion of various surfactants.Due to the different properties and application value of different phases,the phase behavior of surfactant system has been widely concerned.At the same time,due to the close relationship between the rheological properties of surfactant system and its phase,the research on its rheological value has important guiding significance for the actual industrial production.The composite system of surfactant and polymer has a wide range of applications in daily chemistry and medical field.It is of great significance to study the interaction mechanism between surfactants and polymers for better guiding practice.In this paper,we investigate the phase behavior and rheological properties of quaternary ammonium salt cationic surfactant Rewoquat Cl-deedmac/PVA(polyvinyl alcohol)/Glycerin/H₂O pseudo-ternary system at room temperature using a polarizing microscope,small angle X-ray scattering,and a rheometer.Base on the experimental data obtained,we constructed a phase diagram of the pseudo-ternary system.Three main liquid crystal phases were identified—hexagonal,lamellar,and vesicle.The results reveal that the vesicles in the lyotropic liquid crystal region occupy the largest area of the phase diagram.The rheological analysis results indicate the lyotropic liquid crystal to be a non-Newtonian fluid with yield stress and high viscoelasticity.The phase region of the lyotropic liquid crystal shows shear thinning,which is characteristic of pseudoplastic fluid.The lamellar liquid-crystal system exhibits solid-like properties over the whole frequency scanning range.The vesicles have obvious yield stress value and their frequency scanning curve is similar to that of the lamellar liquid crystal,which means the vesicle system also has high viscoelasticity.In addition,the effects of different additives on the phase behavior of cationic surfactant and polymer composite system were studied.Meanwhile,a preliminary study on the solid foam material formed by the surfactant and PVA composite system under the action of plasticizer and polymer compound was carried out,which provided a theoretical basis for the formulation design of surfactant polymer composite system.