We study aqueous suspensions of charged gibbsite platelets that show the isotropic (I) to nematic (N) phase transition. This is the first case where the I-N transition in a dispersion of charged colloidal platelets is not impeded by gelation since Langmuir's classic work on dispersions of clay particles more than sixty years ago ( J. Chem. Phys. , 6 (1938) 873). On increasing particle concentration, our dispersions subsequently show an isotropic, nematic and gel phase. We attribute the shift of the gelation boundary from below to above the I-N transition to the surface modification of the gibbsite platelets with aluminium polycations, which are known to enhance the stability of gibbsite colloids significantly.
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Beek et al. (2003) studied this question.