LATEX FILM SURFACE-MORPHOLOGY STUDIED BY ATOMIC-FORCE MICROSCOPY - EFFECT OF A NONIONIC SURFACTANT POSTADDED TO LATEX DISPERSION

The effect of a non-ionic surfactant postadded to surfactant-free poly(butyl methacrylate) latex dispersions, on the morphology of dry film surfaces has been studied by atomic force microscopy. An optimal surfactant concentration corresponding to the full coverage of the latex particles was found to yield the best ordering and packing of the particles at the film surface. This result is explained taking into account steric stabilization and depletion flocculation effects between particles during the drying process. This result indicates that depletion phenomena must also probably be considered in the interpretation of the result obtained previously [D. Juhue and J. Lang, Langmuir, 9 (1993) 792] with an anionic surfactant of similar structure to the non-ionic surfactant used in the present work.