Preparation of polyurethane-acrylate and silica nanoparticle hybrid composites by a free radical network formation method

Abstract

In this study, hybrid composites of polyurethane-acrylate (PUA) and silica nanoparticle were prepared by a radical method. For this aim, silica nanoparticles were chemically functionalized with 3-methacryloxypropyltrimethoxysilane. Polyurethane was synthesized and then modified with 2-hydroxyethyl methacrylate to yield PUA. Then, different amounts of modified-silica were used to prepare PUA composites by the addition of an ethylene glycol dimethacrylate crosslinker. Fourier-transform infrared spectroscopy confirmed the successful functionalization of silica nanoparticles and the preparation of PUA. Structural investigation of the functionalized-nanoparticles and also nanocomposites was carried out using X-ray diffraction and electron microscopy. According to the thermal gravimetric analysis results, char residue of $\hbox {HSiO}_{2}$ is 86.6%, which decreases to 81.3% in the case of $\hbox {MSiO}_{2}$ as a result of its modifier degradation content of 5.3%. PUAS5 shows main decomposition temperatures of 396.5 and $454.9{^{\circ }}\hbox {C}$ and also char content of 5.7% at $700{^{\circ }}\hbox {C}$. The high amount of $\hbox {MSiO}_{2}$ can also be resulted in higher degree of crosslinking and therefore higher thermal stabilities and char residue.