SANS study of partially fluorinated terphenyl liquid crystals under spatial confinement

We report a small-angle neutron scattering (SANS) study of partially fluorinated terphenyl-based liquid crystals confined in anodic aluminium oxide (AAO) membranes with various pore diameters. The analysis combines structural imaging by scanning electron microscopy (SEM) with a scattering model that incorporates both the pores’ arrangement structure factor and a specific form factor, enabling quantitative insight into the spatial distribution of liquid crystalline material inside cylindrical nanochannels. In sufficiently narrow pores (20 and 40 nm), the confined liquid crystals exhibit paranematic ordering – a weakly anisotropic state induced by surface anchoring and geometric constraints – which is absent in 200 nm pores. The scattering length density profiles extracted from the data reveal a core–shell modulation, with significantly reduced density in the central region of the pore. The paranematic shell thickness is shown to depend on both pore size and molecular dimensions. These results provide a framework for interpreting soft-matter ordering under nanoconfinement and demonstrate the sensitivity of SANS to mesoscopic structural gradients in hybrid organic-inorganic systems. • Structure of partially fluorinated terphenyl-based liquid crystals in anodic aluminium oxide membranes studied using combined SEM and SANS. • Specialized small-angle scattering methodology developed for cylindrical pores filled with liquid crystalline molecules with reduced density in the central region of channels. • Paranematic ordering detected and quantitatively described in 20 nm and 40 nm pores, but not in 200 nm pores. • Effective paranematic shell thickness decreases with increasing nanochannel diameter and decreasing molecular size.