Effect of Hofmeister Anions Series on the Langmuir Film of Tetronic 90R4 and Tetronic 701 Block Copolymers

The air-water interfacial behavior of Tetronic 90R4 and Tetronic 701 was studied in the presence of sodium salts with different anions namely $$, $$, $$, $$, Cl^-, Br^-, $$, I^-, and SCN^-. Their presence in the subphase altered the arrangement of both tetronic molecules at the air-water interface. The limiting mean molecular area of the Langmuir film for both tetronics was found to be ion specific; it increased following the series $$< $$< $$< $$< Cl^-< Br^-< $$< I^-< SCN^-, which was found to be aligned with the Hofmeister series of anions. Furthermore, the study explored the effects of the hydration enthalpy, free energy, viscosity B_JD coefficient, and polarizability of these anions on the interfacial behavior of tetronics. The Langmuir-Blodgett film morphology was also examined in the presence of these salt species using SEM. Morphologies were explained considering kosmotropic and chaotropic nature of these anions.