Magnetic Cellulose Nanocrystal Composites: Synthesis, Properties, Applications, and Opportunities

Cellulose nanocrystals (CNCs) are abundant, renewable, biodegradable, non-toxic, and cost-effective nanomaterials with exceptional properties, making them highly appealing for nanocomposite material fabrication. Recognized for their sustainability, CNCs are emerging as promising substrates for the fabrication of functional, stimuli-responsive nanomaterials. This review highlights nanocomposites comprising magnetic nanoparticles with various forms of cellulose-based materials, with a primary focus on magnetic cellulose nanocrystal (MCNC) composites, yielding materials capable of controlled, on-demand responses to external magnetic fields. The magnetic properties of these nanocomposites can be precisely tuned by adjusting the magnetic nanoparticle content on CNC surfaces. At the nanoscale, magnetic CNCs exhibit remarkable properties, including facile and rapid magnetic separation, which holds great potential for numerous applications. This review examines the latest synthesis and modification methods for CNCs functionalized with various magnetic nanoparticles, as well as their applications in the biological, packaging, environmental, and biomedical fields.