Aggregation of Cesium Perfluorooctanoate on Poly(ethylene glycol) Oligomers in Water

Abstract

The interaction of cesium perfluorooctanoate (CsPFO) with poly(ethylene glycol) (PEG) of different molecular weight (300 < or = MW < or = 20000 Da) has been investigated at 298.15 K by isothermal titration calorimetry (ITC), density, viscosity, and conductivity measurements. Calorimetric titrations exhibited peculiar trends analogous to those already observed for sodium dodecyl sulfate (SDS). Micelles of the perfluorosurfactant, as compared to those of SDS, yield complexes with the polymer of similar thermodynamic stability but are able to interact with shorter PEG oligomers. The average number of surfactant molecules bonded per polymer chain at the saturation is about twice that observed for SDS. ITC data at 308.15 K indicate a larger thermodynamic stability of the aggregates but an almost constant stoichiometry. The peculiar thermal effects and the viscosity trend observed during the titration of an aqueous PEG solution with the surfactant appear consistent with a conformational change of the polymer. The PEG chain would evolve from a strained to an expanded conformation, induced by the growing of the surfactant micellar clusters bonded to the polymer, as suggested in a previous study of the PEG/SDS/H2O system.

Physicochemical Studies on the Interfacial and Micellization Behavior of CTAB in Aqueous Polyethylene Glycol Media

“…EG oligomers are not expected to be involved in any other associative interaction with surfactants. However, the cationic micelles can be further stabilized by higher EG homologs as they could wrap around micellar aggregate [36,[44][45][46]. To the best of our knowledge, no systematic study on micellization of CTAB in the presence of EG oligomers of varying molecular weight has been reported.…”

Influence of Surfactants on Hydrophobically End-Capped Poly(ethylene oxide) Self-Assembled Aggregates Studied by SANS

“…This is consistent with results reported recently that emphasize similarity of the aggregation mechanism of perfluorinated surfactant with that observed between SDS and PEO according to the necklace model. 44,45 3.1.3. Effect of the Polymer.…”

Vesicle formation with amphiphilic chitosan derivatives and a conventional cationic surfactant in mixed systems

“…Turbidity measurements are usually used as an easy and effective way to determine the assembling process [32][33][34][35]. The formation of vesicles can be inferred from increases in solution turbidity and directly observed using absorption spectrum.…”