Monolayers of 14-H-perfluorotetradecane-1-carbonic acid

Abstract Monolayers of 14-H-perfluorotetradecane-1-carbonic acid (PFTDA) at the air-water interface with different metal cations (K + , Cd +2 , Cu 2+ , A1 3+ , Fe 3+ ) dissolved in a water subphase were studied. The dependence of the surface pressure P ( A ) and the jump of the surface potential ΔV on the area per molecule A in the monolayer were studied. Some compression isotherms of the PFTDA monolayers within a wide surface pressure range obey the equation of state P(A−A 0 ) = kT n , where A o is the effective area of interaction of the molecules in the monolayer, n = 1 − 4 and it depends on the interaction of the polar groups with one another or with the cations of the subphase. On the whole, this is the evidence of a weak cohesive interaction between the hydrophobic radicals in the monolayer.