Robust, magnetic cellulose/Fe3O4 film with anisotropic sensory property

Fe3O4/cellulose composite films with anisotropic structure and properties were fabricated. Blend solution of Fe3O4 nanoparticles and cellulose in benzyltrimethyl ammonium hydroxide aqueous solution was subjected to magnetic orientation, followed by regeneration and mechanical stretching, leading to alignment of Fe3O4 nanoparticles as whisker or wire like aggregates in the cellulose matrix. The composite films showed magnetic and mechanical anisotropy with higher saturated magnetization, remanence and tensile strength in the direction parallel to the orientation direction, due to the anisotropic structure. When used as magnetic sensors, the composite films demonstrated anisotropic response to external magnetic field, namely, the current attenuation ratio in the perpendicular direction was 15.8%, while in the parallel direction it was 31.1% which was almost double of that in the perpendicular direction. The composite films also possess fast responsiveness and excellent reproducibility, potential as magnetic sensors and smart devices. In addition, the composite films also displayed excellent UV shielding property. The present work not only provides a facile pathway to fabricate smart devices, but also takes advantage of the bioresource, demonstrating potential in sustainability.