Photoinitiator-Free UV-Cured Acrylic Coatings Containing Magnetite Nanoparticles

A dispersion of magnetite nanoparticles in hexane has been added to 1,6-hexanediol diacrylate at 5–40 phr. The obtained formulations have been polymerized by means of UV light in the absence of any radical photoinitiator and the cured films have been fully characterized. The photoinitiator activity of the magnetite nanoparticles is demonstrated: upon photoexcitation, Fe3O4 can generate radicals which in turn start polymerization chains. Isothermal magnetization curves showed that at room temperature, the cured material exhibits no hysteretic features, indicating a superparamagnetic-like behavior. At temperatures below 100K, a significant magnetic hysteresis gradually appears but a substantial fraction of magnetic nanoparticles is still in the superparamagnetic phase even at T=10K.