Fabrication and properties of superparamagnetic UV-curable nanocomposites based on covalently linked waterborne polyurethane/functionalized hollow Ni0.3Zn0.5Fe2O4 microspheres

UV-curable nanocomposites based on waterborne polyurethane (WPU)/hollow Ni0.3Zn0.5Fe2O4 nanospheres (h-NZFO) have been successfully synthesized via an in situ polymerization method. The h-NZFO nanoparticles prepared using the solvothermal method were modified with isophorone diisocyanate (IPDI) via a chemical method to improve the compatibility with the monomers. The functionalized hollow Ni0.3Zn0.5Fe2O4 filler (h-NZFO-NCO) acted as an efficient crosslinker in the prepolymer and combined with waterborne polyurethane through chemical bonding instead of the conventional physical mixing. It was found that the h-NZFO-NCO nanoparticles were wrapped and dispersed homogeneously in the WPU matrix. Moreover, the introduction of h-NZFO-NCO obviously contributed to the thermal stability, glass transition temperature (Tg), emulsion stability and magnetic properties of the WPU/h-NZFO nanocomposite. The saturation magnetization of the nanocomposites can reach up to 15.24 emu cm−3 with h-NZFO-NCO doping at 8%, which would have potential application in the microwave absorption field.