Mayr Lina, Amschler Sonja, Edenharter Andreas, Dudko Volodymyr, Kunz Raphael, Rosenfeldt Sabine, Breu Josef
Department of Chemistry and Bavarian Polymer Institute, University of Bayreuth, 95447 Bayreuth, Germany.
Langmuir. 2020 Apr 14;36(14):3814-3820. doi: 10.1021/acs.langmuir.0c00373. Epub 2020 Mar 31.
The swelling of clay minerals in organic solvents or solvent mixtures is key for the fabrication of polymer nanocomposites with perfectly dispersed filler that contain only individual clay layers. Here, we investigated the swelling behavior of sodium hectorite in different ternary solvent mixtures containing methanol, acetonitrile, ethylene glycol, or glycerol carbonate with minimal amounts of water. We found that in these mixtures, less water is required than in the corresponding binary mixtures to allow for complete delamination by repulsive osmotic swelling. A quantitative study of osmotic swelling in a particular ternary mixture shows that organic solvents resemble swelling behavior in pure water. At hectorite contents larger than 5 vol %, the separation of individual layers scales with ϕ. At this concentration, a crossover is observed and swelling continues at a slower pace (ϕ) below this value.
