Liquid crystal diffusion in thin films investigated by PFG magnetic resonance and magnetic resonance imaging

NMR is a well-established technique to study orientational order and dynamics of liquid crystals. We present a study of liquid crystal MBBA properties in both bulk and constrained thin film capillaries (thickness ∼200 μm) at different temperatures. Translational self-diffusion measurements have been performed in the nematic and isotropic phases. For constrained samples in the isotropic phase the diffusion coefficient has orientational dependence (D∥/D⊥ ≈ 7). To characterize the diffusion distribution of liquid crystals within the thin film, a diffusion mapping experiment was performed. The method provides accurate diffusion coefficients (D∥ and D⊥) measurements with a pixel resolution of 4 μm.