Magnetic alignment of nontronite dispersions

• Iron rich nontronite nanoclay phase behaviour in magnetic fields
• Nontronite nanoclay self-ordering occurs within minutes in magnetic field below 2 T.
• An alignment kinetic model is derived from optical birefringence measurements.

The time dependent alignment of exfoliated nontronite dispersions subjected to moderate magnetic field strengths (B < 0.8 T) is investigated. The chemical and physical properties of nontronite are thoroughly characterised as well as the phase behaviour of its aqueous dispersions at concentrations between 0.2 and 0.7 vol.%. The degree of nontronite alignment is associated with a birefringent light glow which increases with magnetic field strength, time and clay mineral concentration. Theoretical modelling indicates that the experimentally determined alignment kinetics have a characteristic timescale best described by a probability distribution. These findings are of importance for designing the optical, mechanical and barrier properties of clay polymer nanocomposites.

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