Ionomer Morphology, Solution to Film Thermodynamics, Molecule Transport, Physical Properties, and Water Desalination via Electrodialysis

Of the different classes of separation polymers, ionomers are considered one of the most advanced and versatile. They have been successfully utilized in various industrial fields, including electrodialysis, electrolysis, diffusion dialysis, solid polymer electrolyte batteries, sensing materials, medical use, and analytical chemistry. In this study, an ionomer film series of penta block copolymer (PBC, poly(t-butyl styrene-bhydrogenated isoprene-b-sulfonated styrene-b-hydrogenated isoprene-b-t-butyl styrene) (tBSHI-S-HI-tBS)), sPP (sulfonated polyphenylene), aminated PPSU-TMPS block copolymer (polyphenyl sulfone-tetramethyl polysulfone), and Nafion were investigated with respect to thermodynamics, morphology, mechanical and transport properties. First, the thermodynamic interrelationships between wettability, surface energy, solubility, and swelling were studied in order to probe ionomer relationships between microscopic interactions and macroscopic physical properties. Choosing an appropriate surface energy model and an optimal solubility prediction method is an important role in the study of intrinsic and extrinsic ionomer properties. Second, with the aim of improving ionomer film characteristics, various casting solvents (tetrahydrofuran, chloroform, cyclohexane:heptane (C:H 1:1 wt%)), temperature, and processing methodology were utilized. Material solubility parameters and subsequent interactions between ionomer chains and solvent molecules define its morphological growth and ultimate microstructures. This morphology has a great impact on the distribution of functional groups, and transport properties of water and ions. As an example, the proton conductivity of THF-cast PBC1.0 membrane (15.88 mS/cm) is significantly improved over that of C:H-cast PBC1.0 membrane (1.09 mS/cm). Third, various ionomer pairs were used to improve the water desalination via electrodialysis. Finally, my fourth area and future work is mainly focused on the synthesis and characterization of aminated PPSU-TMPS block copolymers in order to form a systematic understanding of the material's properties that is critical for industrial application and chemical engineering fields. In conclusion, a comprehensive ionomer system has been set up to manufacture better performance films with higher proton conductivity used in the fuel-cell industry, designed materials with appropriate swelling properties that are vital to the electrodialysis desalination process, neutralized cations for battery research, and other engineering applications.