Functionalization of polysiloxanes by esterification of pendant glycidic groups: Acetylation as a model reaction

The esterification of polysiloxane-bound epoxy groups provides a versatile route to functionalized silicone copolymers. The model reaction of acetic acid with pendant glycidic groups in the presence of a tertiary amine as a catalyst was investigated. Chromatographic and spectroscopic studies of the resulting polysiloxanes showed that no detectable unwanted side-reaction takes place when the reaction is carried out under mild conditions; long-chain polysiloxanes having high functionalization rate were obtained as gummy products almost insoluble in toluence because of stronger inter-molecular associations by hydrogen-bonding. Convenient flow properties as well as good solubility in common organic solvents could, however, be easily achieved upon acetylation of hydroxylic groups.