Unraveling the interaction mechanism of sodium cholate with Tetronic ® 1304: correlation of surface properties and thermodynamics

Abstract Understanding the thermodynamics of intermolecular interactions is essential for evaluating the feasibility and stability of mixed micellar systems intended for nanoformulation applications. In the present study, the interaction between the bioamphiphile bile salt sodium cholate (NaC) and the star-shaped block copolymer Tetronic ® 1304 (T1304) was investigated in aqueous solution. The concentration of T1304 was maintained constant, while the concentration of NaC was systematically varied to elucidate their interaction behavior. Surface tension and viscosity were simultaneously measured using a Borosil Mansingh Survismeter , and the corresponding thermodynamic parameters were calculated from the experimental data. The negative values of Gibbs free energy (ΔG) indicate a thermodynamically favorable interaction between NaC and T1304, consistent with the formation of T1304-NaC mixed micellar aggregates. The negative enthalpy changes (ΔH) values suggest that the interaction between NaC and T1304 is exothermic. These findings provide thermodynamic insights into the interaction between NaC and T1304 and support the formation of a spontaneous, enthalpy-driven mixed micellar system.