title: Isotropic-nematic phase transition in aqueous sepiolite suspensions.
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.
authors.affiliation: School of Chemistry, University of Bristol, Bristol BS8 1TS, UK. Electronic address: chzpw@bristol.ac.uk.
authors.forename: Phillip
authors.initials: P
authors.lastname: Woolston
authors.affiliation: School of Chemistry, University of Bristol, Bristol BS8 1TS, UK.
authors.forename: Jeroen S
authors.initials: JS
authors.lastname: van Duijneveldt
keywords: Aqueous; Clay; Nematic; Polyacrylate; Rodlike colloids; Sepiolite