IMPACT OF THE COMBINED USE OF MAGNETITE NANOPARTICLES AND CELLULOSE NANOCRYSTALS ON THE SHAPE-MEMORY BEHAVIOR OF HYBRID POLYURETHANE BIONANOCOMPOSITES.

Thermo bio-based polyurethane (PU) matrix, cellulose nanocrystals (CNCs), and magnetite nanoparticles (MNPs) were prepared. The integration of the two nanoparticle types resulted in tough materials that display a higher stiffness and storage modulus in the glassy and rubbery state, thus contributing to the structural reinforcement, as well as magnetic properties, reflecting a synergistic effect of this combination. A quantitative characterization of the shape-memory properties revealed that the addition of CNCs led to an increase of the shape fixity, due to the higher glass transition temperature (Tg) and the higher stiffness below Tg than the neat PU, while the addition of MNPs made it possible to activate the shape recovery by applying an alternating magnetic field. Moreover, the new hybrid bionanocomposites showed good bio- and hemo-compatibility.