Ammonium perfluorononanoate

Ammonium perfluorononanoate (APFN) is an anionic surfactant that in water forms liquid crystalline phases (Lyotropic liquid crystal). It is the ammonium salt of perfluorononanoic acid.

The phase diagram of APFN/H2O system is delineated by the presence of a lamellar phase and a nematic phase with awide isotropic solution. The nematic phase is of the type I, and the aggregates have a positive and diamagnetic anisotropy. In the presence of a magnetic field, the aggregates align parallel to the field direction. The change of phase at the lamellar-nematic temperature has been ascribed to order-disorder transitions.

MLV Formation
It has recently been shown that the lamellar phase of the APFN/2H2O system form multilamellar vesicles under shear rate.

Restrictions
In 2020, a California bill was passed banning APFN as an intentionally added ingredient from cosmetics.