Preparation of MT ‐type polysiloxane containing active vinyl groups with low hydroxyl group content

Abstract MT‐type polysiloxanes containing active vinyl group were prepared under acid conditions initiated from divinyltetramethyldisiloxane and methyltrimethoxysilane by one‐pot method, co‐hydrolysis method, and reaction‐rectification coupling method, respectively. The influence of different methods on molecular weight, molecular weight distribution, and ratios of each kind of segment in the MT‐type polysiloxane containing active vinyl group were discussed in detail. The results indicated that with the reaction‐rectification coupling method, the residual hydroxyl segment in the prepared MT‐type polysiloxane could be lower than 0.5 wt%. For MT‐type polysiloxanes with high hydroxyl group content, the hydroxyl content could be reduced when treated with hexamethyldisilazane, trimethylchlorosilane, zinc naphthalate, or tetramethylammonium hydroxide under suitable conditions. Hexamethyldisilazane was the most convenient and effective regents among these four compounds, the residual hydroxyl content contained in the prepared MT‐type polysiloxanes could be reduced from 13.4 to 0.9 wt% when MT‐type polysiloxane sample was treated with hexamethyldisilazane.