Investigatin of phase transmission dynamics in multiple cation environment by light scatter method

Polyelectrolytes are polymers that dissolve in water by ionization. Polyelectrolytes are ubiquitous in all life forms and are frequently used in biotechnology, food and pharmaceutical industries. The phase diagrams of polyelectrolytes depend on concentration of polymer, type of the solvent, salt and ion concentration and temperature. Entropy due to its chain confirmation and Coulomb electrostatic forces in the polar solvent environment make the study of the phase structures and phase transition dynamics complicated. In this thesis, phase diagram and phase transition dynamics of flexible polyelectrolyte in a multi-cation environment have been studied experimentally. In the first part of the study, phase diagram of a system of water soluble flexible polyelectrolyte Sodium PolyStyrene Sulfonate (NaPSS) and divalent salt Barium Chloride (BaCl2) has been measured and the dynamics of phase transition has been investigated at various polyelectrolyte concentrations. In the second part, Sodium Chloride (NaCl) salt has been added to the dual system. Phase diagram and the dynamics of phase transition of this tertiary system has been studied. The phase diagram was constructed by measuring the light transmission of the solutions and the dynamics of phase transition at various temperature quenches around the critical temperature has been investigated thoroughly by the Small Angle Light Scattering method. Data and image analysis have been accomplished by codes written in the LabView program. After the performed experiments salt concentration at millimolar level has been found to change the phase diagram. The effect of temperature quenches on the dynamics of phase diagrams have been studied in both double and tertiary systems. The phase change in both systems do not evolve via the dominant concentration population with a critical size, but the phases grow at each size simultaneously. The current phase transition theories of neutral polymer systems fail to explain this outcome of polyelectrolyte phase transition.