SURFACE AND INTERFACIAL FTIR SPECTROSCOPIC STUDIES OF LATEXES .10. THE EFFECT OF COALESCENCE ON SURFACTANT EXUDATION IN POLYSTYRENE AND POLY(N-BUTYL ACRYLATE) LATEX FILMS

摘要

In an effort to establish to what extent transient effects prior to coalescence may influence mobility, distribution, and orientation of surfactant molecules after coalescence, poly(n-butyl acrylate) (n-BA) and polystyrene (Sty) were polymerized independently and mixed in a 5 : 1 ratio. It appears that if a mixture of the n-BA and Sty latex particles is allowed to stabilize prior to coalescence, the time of stabilization may have a significant effect not only on the distribution of SDOSS surfactant molecules across the coalesced film, but also on their orientation changes depending upon the stage of coalescence and the water front moving toward the surface. The coalescence of latex films was conducted under gaseous nitrogen and at 60% relative humidity. While the water front moves from the film-substrate upward, during this process, various segments of the surfactant molecule change their orientation. Near the F-A interface, hydrophobic segments are being reoriented from parallel to perpendicular, whereas preferentially parallel orientation exhibit hydrophylic SO3- Na+ segments. When water molecules, however, diffuse out of the film, the surfactant molecules have no preferred orientation. (C) 1995 John Wiley & Sons, Inc. [References: 13]