Organic-inorganic hybrid from ionomer via sol-gel reaction

Transparent organic-inorganic hybrid material was synthesized via the sol-gel method using polyethylene-co-Zn-acrylic acid (Zn-PEAA) ionomer and a metal alkoxide, tetraethyl orthosilicate (TEOS). The resulting material was characterized using various spectroscopic, microscopic, and thermal techniques. Photoacoustic Fourier transform infrared spectroscopy (PA-FTIR) and Si-29 solid-state nuclear magnetic resonance spectroscopy (29Si solid-state NMR) results prove that silica is formed via the sol-gel reaction. Scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDAX), transmission electron microscopy (TEM), and atomic force microscopy (AFM) studies indicate that silica particle size is in nanoscopic level (50 nm average size), and silica nanoparticles are uniformly dispersed in the polymer matrix after the sol-gel process. Thermogravimetric analysis (TGA) results show that the silica content of the hybrid is about 19%. The thermal stability of the ionomer increases after hybridization. The crystallinity of the hybrid material is found to decrease from modulated differential scanning calorimetry (MDSC) and wide-angle X-ray scattering (WAYS) results. Dynamic mechanical analysis (DMA) of the hybrid shows that the storage modulus of ionomer increases after the sol-gel reaction, and the order-disorder transition temperature of the ionic cluster also increases, indicating the existence of silica mostly in the microphase separated cluster template.