Three-dimensional hierarchically organized magnetic nanoparticle polymer composites: Achievement of monodispersity and enhanced tensile strength

Synthesis of monodisperse polymer-inorganic nanoparticle composites and the study of their mechanical properties are described. Surface-modified MPt (M = Fe, Ni) nanoparticles undergo hydrosilation reaction with siloxane backbones and make covalent networks by acting as crosslinkers. Monodispersity and the spatial resolution of nanoparticles were identified with atomic force microscopy and transmission electron microscopy. The properties of covalent bonding in the elastomeric network between nanoparticles, allyl-modified dopamine, and siloxane backbones were studied with X-ray photoelectron spectroscopy and IR. The added amount of dopamine-modified FePt nanoparticles affected the crosslinking density in the siloxane backbones. The intensity of Si-H bonding was decreased in IR spectra with increasing density of FePt nanoparticles. Mechanical properties were measured with nanoindentation. FePt nanoparticle polymer composites have more enhanced tensile strength (E-r = 1.56 GPa, H = 0.126 GPa) than simple elastomers crosslinked with diallyl carbonate (E-r = 0.67 GPa, H = 0.115 GPa). Further improvement of mechanical strength was achieved with increased amount of dopamine-modified nanoparticles due to the increase in the crosslinking density between siloxane backbones.