The physicochemical behavior of the newly synthesized fluorinated 5-hydroxyamino-3-perfluoroheptyl-1,2,4-oxadiazin-6-one (PFHO) surfactant was investigated. Thermal analysis showed that the pure surfactant is thermallystable under an inert atmosphere to 135 C, which is several degrees higher than the melting point (99 C). PFHO israther active at the water/air interface where it assumes a standing up configuration. It exhibits an enhanced selfassemblingbehavior; accordingly, the critical micellar concentrations at some temperatures are 2 orders of magnitudelower than those of a similar surfactant having the same phobicity, such as sodium perfluorooctanoate. Even in thedilute domains, PFHO forms large micelles, detected by dynamic light scattering studies, that are precursors of the geloccurring at rather low composition (only 2.0% w/w at 25 C). Optical microscopy evidenced cylindrical aggregates ingel systems whereas differential scanning calorimetry and viscosity showed that the gels are stable over a widetemperature range to ca. 70 C where they undergo a reversible gel f fluid transition. Finally, percolation theorycombined with data provided by the experimental studies enabled us to predict the PFHO gelation process correctly, invery good agreement with the experimental findings.
|Number of pages||8|
|Publication status||Published - 2009|
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Surfaces and Interfaces