MOLECULAR AREAS OF SOAPS AT THE SURFACE OF LATEX PARTICLES

Abstract

The molecular area (i.e., the area occupied by a molecule of soap adsorbed on a surface) has been determined for a number of anionic, cationic, and non-ionic emulsifiers, adsorbed on latex particles. Measurements were made by surface tension and electron microscopic techniques. The composition of the polymer did not affect the molecular area of either anionic or cationic soaps. When a mixture of non-ionic and anionic soaps was used, interaction between the soaps prevented application of the conventional methods for measuring molecular area. The interaction is manifested by a decrease in the area occupied by an anionic soap molecule which can be explained in terms of reduction in electrostatic repulsive forces between ionic soap molecules. The configuration of the polyethylene oxide chain of the non-ionic on the surface of the latex particle is deduced to be that of caterpillarlike folds.