Studies on the aminolysis of RTV silicone rubber and modifications of degradation products

Abstract

The degradation of room temperature vulcanized (RTV) silicone rubbers, swelled in different solvents and followed by the aminolysis reaction using diethylamine as a nucleophilic reagent, was studied. The reaction was further facilitated with a potassium hydroxide catalyst dissolved in ethanol. When the silicone rubber swelled in a less polar solvent, toluene, the main product of the aminolysis reaction was a linear polydimethylsiloxane with hydroxyl and ethoxy end groups (EtO–PDMS–OH), and an average molecular weight of 15,000. On the other hand, when a polar solvent, tetrahydrofuran, was used, the degradation rate was increased, and significant amount of cyclic compounds were found in addition to the linear PDMS. Furthermore, if different alcohols were used to dissolve the KOH catalyst, the degradation rate and the product distribution were both changed. The dissolution time decreased in the following order: glycerol > ethylene glycol > 1,4-butanediol > ethanol. In this study, efforts have also been made to improve the reusability of the aminolysis products by changing their terminal groups.