Synthesis and characterization of the surface modified titanium dioxide/epoxy nanocomposites

TiO2 nanoparticles, obtained by acid catalyzed hydrolysis of titanium isopropoxide, were surface modified by three gallic acid esters with different hydrophobic part length: octyl, decyl and lauryl gallate, and then used to prepare TiO2/epoxy nanocomposites. The characterization of the surface modified TiO2 nanoparticles was performed by FTIR and UV-Vis spectroscopy. The influence of different gallic acid esters and content of modified TiO2 nanoparticles on the glass transition temperature (Tg), rheological, barrier and mechanical properties of the nanocomposites was investigated by DSC, DMA, water vapor permeability test and König pendulum. The presence of the surface modified TiO2 nanoparticles in epoxy resin caused the increase of Tg and decrease of the water vapor permeability. However, the length of the nonpolar gallate part showed no effect on Tg of the synthesized nanocomposites, while the increase of the nanofiller content resulted in the increase of Tg. With increasing the hydrophobic part chain length of gallate ligand, the water vapor transmission rate decreased, while the hardness of the nanocomposites did not change.