US EPA

3859620 

Journal Article 

Micellization of lithium perfluoroheptanoate and its aggregation on poly(ethylene glycol) oligomers in water 

Gianni, P; Bernazzani, L; Carosi, R; Mollica, V 

2007 

1 

Langmuir
ISSN: 0743-7463
EISSN: 1520-5827 

23 

17 

8752-8759 

English 

17645360 

10.1021/la701190g 

WOS:000248730500022 

The interaction of lithium perfluoroheptanoate (LiPFHep) with poly(ethylene glycol) (PEG) of different molecular weights (300 < MW < 20 000 Da) was investigated in water at 298.15 and 308.15 K by the isothermal titration calorimetry (ITC). Density and sound velocity measurements were also performed at 288.15, 298.15, and 308.15 K, while viscosity and conductivity data were only collected at 298.15 K. The aggregation process of this surfactant on the PEG polymeric chain was found to be very similar to the process exhibited by the two homologous perfluorooctanoate and perfluorononanoate. Viscosity and ITC data indicated that the formation of polymer-surfactant complexes between PEG and LiPFHep also leads to a conformational change in the polymer. The aggregation of micelles of the lithium perfluoro surfactants on the PEG polymeric chain is characterized by a comparable thermodynamic stability, which results from a balance of enthalpy and entropy contributions, which both increase with the length of the surfactant hydrophobic chain.