Abstract
Interaction of 1,10-pehanthroline (phen) and metal (II) thiocyanato complexes with nonionic micelles of poly (ethylene oxide) (PEO) type surfactant, Triton X, with varying its chain length has been investigated by potentiometric, spectrophotometric, and calorimetric titration at 298 K. Data are well explained in terms of the association model in which the species accommodated in Triton X micelles are expressed as an adduct with a surfactant molecule, as well as the phase distribution model in which the micelles provide microscopic non-aqueous phase. The distribution constant, transfer enthalpy and entropy from aqueous to micellar phase significantly depend on the PEO chain length of the surfactant. This suggests the intramicellar heterogeneous structure consists of PEO and hydrophobic region of the surfactant. The intrinsic thermodynamic parameters of transfer and/or the complex formation in each region have been determined. These values indicate the hydrogen-bonding network weekly remains in PEO phase of the micelles while the core phase resembles non-aqueous solvent.
https://ror.org/00p4k0j84 
