Isotropic-nematic phase transition in aqueous sepiolite suspensions
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Published on: October 31, 2019
Phillip Woolston1, Jeroen S van Duijneveldt1
1School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
Abstract:
Aqueous suspensions of sepiolite clay rods in water tend to form gels on increase of concentration. Here it is shown how addition of a small amount (0.1% of the clay mass) of a common stabiliser for clay suspensions, sodium polyacrylate, can allow the observation of an isotropic-nematic liquid crystal phase transition. This transition was found to move to higher clay concentrations upon adding NaCl, with samples containing 10(-3) M salt or above only displaying a gel phase. Even samples that initially formed liquid crystals had a tendency to form gels after several weeks, possibly due to Mg(2+) ions leaching from the clay mineral.
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