Cobalt iron oxide-infused silicone nanocomposites: Magnetoactive materials for remote actuation and sensing

Magnetoactive polymer composites (MAPCs) are promising smart materials owing to their shape-changing behaviour in response to magnetic fields. MAPCs find promising niches in several applications, including soft robotics, sensors, biomedical implants, smart prosthetics, and flexible electronics. Although several works have reported the synthesis of magnetic-responsive polymer composites, this work utilizes highly magnetic nanoparticles (i.e. cobalt iron oxide) to produce extremely soft MAPCs. Novel MAPCs were developed using room-temperature vulcanizing (RTV) silicone rubber as the base matrix, incorporating cobalt iron oxide (CoFe2O4, referred to as CIO) nanoparticles as the magnetic filler. Varying concentrations of CIO nanoparticles (0.25, 0.5, 1, and 3%) were used to synthesize isotropic and anisotropic MAPCs. Silicone/CIO MAPCs were characterized for their microstructural, thermal, mechanical, and magnetic properties. An increase in the CIO nanoparticle concentration within the silicone matrix resulted in an improved mechanical performance, where a compressive modulus of 0.199 MPa for silicone/0.25% CIO improved to 0.340 MPa for silicone/3% CIO. Likewise, an improved tensile strength was observed due to particle alignment, resulting in an increase from 1.25 MPa (for isotropic samples) to 1.356 MPa (for anisotropic samples) in silicone/1% CIO MAPCs. Silicone/CIO MAPCs also revealed a higher failure strain than pure silicone samples. Finally, an improvement in the magnetic properties of MAPCs was observed with increasing CIO concentrations, where increased saturation magnetization from 0.087 to 1.057 EMU/g and remanence from 0.054 to 0.625 EMU/g were recorded with an increase in CIO content from 0.25 to 3% in the silicone matrix. The silicone/CIO composites exhibited suitable magnetic responsiveness and mechanical characteristics that make them promising materials for applications in remote actuation and sensing.