Change in the structure of heat-treated siloxane oligomers as observed by FT-IR

The influence of treatment conditions on the structure of siloxane oligomers was studied by using alkoxysilane compounds. The siloxane structure was analyzed by diffuse reflectance spectroscopy of FT-IR. KBr was treated directly with a solution of alkoxysilane, and was used as a sample. As a result of evaluating the relationship between the treatment conditions and the formation ratio of linear siloxane, when the concentration of the alkoxysilane was low, the siloxane becomes difficult to form, but the formation ratio of linear siloxane components was enhanced. This tendency was more remarkable in alkoxysilane compounds of the dimethoxy series than in those of the trimethoxy series. The formation ratio of linear siloxane was lower in alkoxysilane compounds having ethoxy groups than in those having methoxy groups. On the other hand, the formation ratio of linear siloxane was increased with decreasing boiling point of the solvent used for treatment. This tendency was more remarkable in alcohols than in ketones.