Self-sensing magnetic actuator based on sustainable collagen hybrid nanocomposites

Taking into account that natural polymers are renewable and biodegradable, hybrid materials based on natural polymers are required for advanced technological applications with reduced environmental footprint. In this work, sustainable composites have been developed based on collagen as a polymeric matrix and different magnetic fillers, in order to tailor magnetic response. The composites were prepared by solution casting with 30 wt% of magnetite nanoparticles (Fe3O4 NPs), magnetite nanorods (Fe3O4 NRs) or cobalt ferrite nanoparticles (CoFe2O4 NPs). It is shown that the magnetic filler type has no bearing on the morphology, physical-chemical, or thermal characteristics of the composites, whereas the mechanical properties are determined by the magnetic filler, leading to a reduction in tensile strength, with values of 4.95 MPa for Fe3O4 NPs, 9.20 MPa for Fe3O4 NRs and 5.21 MPa for CoFe2O4 NPs containing samples. However, the highest magnetization saturation is obtained for Fe3O4 NPs (44 emu.g(-1)) and the higher coercive field for CoFe2O4 NPs (2062 Oe). In order to prove functionality of the developed composites, a self-sensing magnetic actuator device has been developed with the composite film with CoFe2O4 NPs, showing high stability over cycling.