Latex Surface and Bulk Coagulation Induced by Solvent Vapors

• Published in: Journal of colloid and interface science 2000-08, Vol.228 (1), p.171-177
• Main Authors: Braga, Melissa, da Silva, Maria do Carmo Vasconcelos Medeiros, Cardoso, André Herzog, Galembeck, Fernando
• Format: Article
• Language: English
• Subjects: Applied sciences; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Installations for energy generation and conversion: thermal and electrical energy; latex film formation; Other installations: mhd power plants, fuel cell plants, incineration plants, etc; PS latex stability; solvent effects on latex stability; solvent-induced coagulation
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1006/jcis.2000.6920

Latex exposure to solvent vapors leads to highly specific changes in latex stability as well as on the morphologies of the particle association products, depending on the latex and solvent used. Examples of solvent vapor-induced aggregation are given: surface films are obtained on two PS latexes; in one case, the film surface is mirror-reflective and very flat, as evidenced by AFM. Another PS latex coagulates under exposure to acetone vapors, and the morphologies of the coagula are highly sensitive to the exposure conditions. This latex yields a highly porous foam-like structure, in which particles are strongly coalesced but form percolating patches around the pores. The same latex but under other conditions produces a coagulum of large numbers of aggregated particles with a raspberry-like morphology. Density centrifugation experiments show that the effect of solvents on different latex fractions is not uniform, and some fractions show larger density changes than others, thus evidencing a variability in their swelling ability.