Abstract
•Clouding/association of surfactant + metformin hydrochloride (MNH) mixtures are studied.•TX-100 + MNH system’s CP was reduced with enhancing of hydrotropes contents.•Micellar parameters of TTAB + MNH system were assessed at different temperatures.•Enthalpy and entropy of clouding/assembly processes were determined and discussed.•Occurrence of H-bonding/electrostatic interaction/hydrophobic forces amid components are suggested.
The clouding development and the association of the mixture of surfactant and antidiabetic drug metformin hydrochloride (MNH) have been investigated in aq. solutions of two anionic hydrotropes (sodium salicylate (NaSal) and sodium benzoate (NaBenz)) and an uncharged hydrotrope (4-amino benzoic acid (4-ABA)) (HDTs) media. In the present study, nonionic (triton X-100 (TX-100)) and cationic (tetradecyltrimethylammonium bromide (TTAB)) surfactants were employed. The cloud point (CP) of TX-100 + MNH system has been reduced with the enhancing contents of HDTs. The micellar variables (critical micelle concentration (CMC) and extent of ionization (α) of TTAB + MNH system have been assessed while the parameters are dependent on the HDT contents and changes of study temperature. The free energy of clouding (ΔGc0) and assembly (ΔGc0) processes have been detected as positive and negative respectively which indicated that the respective processes are non-spontaneous and spontaneous in nature. For the clouding and assembly processes, the standard enthalpy (ΔHc0/ΔHm0), and standard entropy (ΔSc0/ΔSm0) were also determined and discussed. The ΔHc0 and ΔSc0 recommend that the core forces between TX-100 and MNH in presence of 4-ABA are H-bonding and electrostatic interactions but hydrophobic interaction is suggested as main force amid the employed components in aq. NaBenz and NaSal media. The ΔHm0 and ΔSm0 values of TTAB + MNH assembly reveal the occurrence of electrostatic interaction and hydrophobic forces amid the components inspected.