INFRARED STUDY OF EPOXS TEOS TPOT GELS

The thermal changes in the structure of EPOXS-TEOS-TPOT (where EPOXS=epoxysilane, 3-glycidyloxypropyltrimethoxysilane, TEOS=tetraethylorthosilicate, and TPOT=tetraisopropylorthotitanate) derived sol-gel coating materials were followed by infrared spectroscopy. The study showed that for the low-temperature treated gels, the Si-O-Si network was very ''open'', with many organic side groups connecting to it. One of the prominent characteristics of the structure was the presence of four-fold siloxane rings. TiO2 plays a part in the formation of the network by Ti-O-Si bonding. With increasing the TiO2 content in the system, the tendency towards the formation of the four-fold siloxane ring decreased. With increasing heat-treatment temperature, the organic side groups gradually disappeared and, at the same time, the siloxane ring structure decomposed and a more rigid and condensed Si-O-Si network was gradually established.