A. Chittofrati

Dielectric permittivity measurements on highly conductive perfluoropolyether microemulsions at frequencies up to 100 MHz

The impedance analysis technique has been used to measure the complex permittivity and conductivity of highly conductive perfluoropolyether microemulsions. The cell construction details, calibration procedure and data analysis procedure are reported. Examples of dielectric analysis on perfluoropolyether microemulsions are given.

Dielectric behavior of highly conducting perfluoropolyether water-in-oil microemulsions

The dielectric and conductive properties of a new ternary water-in-oil microemulsion consisting of perfluoropolyether (PFPE) oil, PFPE surfactant and water, were investigated by an impedance analysis technique in the frequency range of 5 Hz to 100 MHz. The trend of both the electrical conductivity and the static permittivity was analyzed as a function of the temperature in the interval from -10 to +40/spl deg/C. Maxwell-Wagner relaxation phenomena in the MHz range and a percolative transition, of dynamic type against temperature, were observed. >

Dielectric analysis of the percolation transition in fluorinated water in oil microemulsions

A dielectric analysis of fluorinated water-in-oil microemulsions was performed in the monophasic region of the phase diagram. Trends typical of percolation phenomena were found as well as trends of non percolating systems. At water to surfactant molar ratio 11, the microemulsions show a percolative behaviour described by scaling laws with exponents mainly typical of dynamic percolation. This implies that the droplets, which have in the dilute regime a hydrodynamic radius of 30 /spl Aring/ and interact via an attractive potential as shown by dynamic light scattering, maintain the structure of dispersed droplets upon an increase of the concentration of temperature.