DESORPTION OF THE SURFACTANT FROM THE PARTICLE SURFACE DURING LATEX FILM FORMATION

Properties of latex films are very dependent on the distribution of th e surfactants in the film. It has been recognized that distribution it self depends on the desorption characteristics of the surfactant from the particle-water interface during film formation. This article deals with this problem of surfactant desorption in the particular situatio n of latex film formation. First, FTIR spectroscopic evidence is prese nted for desorption of hexadecyl pyridinium chloride (HPCl) in poly(2- ethyl hexyl methacrylate) (P2EHMA) latex films. Some consequences of d esorption or non-desorption of various surfactants on the structure an d properties of P2EHMA latex films are then presented. This concerns t he crystallization of cationic surfactants, HPCl and hexadecyl trimeth ylammonium bromide (HTAB), in the films and the mechanical properties of films containing ethoxylated nonyl phenol with 10 ethoxy segments ( NP10) or sodium dodecyl sulphate (SDS). In the last part, the determin ation of the fraction of SDS desorbing from the particle-water interfa ce in a model poly(styrene-butyl acrylate-methacrylic acid) latex coal escing in water is described. Other methods for studying desorption ar e proposed.