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Three-Phase Coexistence in Colloidal Rod–Plate Mixtures
- Woolston, Phillip, van Duijneveldt, Jeroen S.
- Langmuir 2015 v.31 no.34 pp. 9290-9295
- blood platelets, clay, gels, montmorillonite, polyacrylic acid, separation, sepiolite
- Aqueous suspensions of clay particles, such as montmorillonite (MMT) platelets and sepiolite (Sep) rods, tend to form gels at concentrations around 1 vol %. For Sep rods, adsorbing sodium polyacrylate to the surface allows for an isotropic–nematic phase separation to be seen instead. Here, MMT is added to such Sep suspensions, resulting in a complex phase behavior. Across a range of clay concentrations, separation into three phases is observed: a lower, nematic phase dominated by Sep rods, a MMT-rich middle layer, which is weakly birefringent and probably a gel, and a dilute top phase. Analysis of phase volumes suggests that the middle layer may contain as much as 6 vol % MMT.