Tuning the Magnetic Alignment of Cellulose Nanocrystals from Perpendicular to Parallel Using Prismatic Lepidocrocite Nanoparticles

We investigated the magnetic alignment degree of ordering of cellulose nanocrystals (CNC) and lepidocrocite nanorods (LpN) pristine and hybrid suspensions, using contrast-variation small-angle neutron scattering (SANS) with in situ magnetic field (0 – 6.8 T) and polarized optical microscopy. The CNC and LpN align perpendicular and parallel to the direction of field respectively, whereas according to the amount of LpN and magnetic field a different behavior is observed. Below 1.0 T the CNC align parallel to the field in the hybrid containing 10 wt% LpN and switches to perpendicular at higher field. In the hybrid containing lower amount of LpN (1 wt%) the ordering of CNC is partially frustrated in all the range of magnetic field, at the same time LpN partially switch from parallel to perpendicular alignment. The present study highlights that the natural perpendicular ordering of CNC can be switch to parallel by weak magnetic fields and the incorporation of paramagnetic nanoparticle as LpN, as well it gives a method to influence the orientation of LpN.