IMAGING HOMOGENEOUS AND COMPOSITE LATEX-PARTICLES WITH AN ATOMIC-FORCE MICROSCOPE

To investigate the morphology of individual latex particles with the a tomic force microscope, the particles were adsorbed onto mica and then dried. Homogeneous and composite latex particles were studied. The pa rticles were made of different amounts of poly(butyl acrylate) and pol y(methyl methacrylate) yielding different viscoelastic properties and different morphologies. During adsorption and subsequent drying, the p acking of the particles is probably mainly determined by capillary for ces; their deformation is caused by interfacial forces. The shape of t he particles on the mica surface depends on their original morphology and their viscoelastic properties. In addition, films formed with the latex particles were imaged to correlate the structure of individual p articles with that of the film surface. In two layers we observed sign ificant deformation of the latex particles although the layer was form ed far below the minimum film formation temperature. Vice versa, in on e film formed above the minimum him formation temperature no deformati on-induced reduction of the nearest neighbor distance was observed.