Determination of silanol end groups in polysiloxanes obtained from dimethyldichlorosilane hydrolysate (DDSH)

Dimethyldichlorosilane hydrolysate, DDSH, the linear part of which contains SiOH end groups, can be used in the preparation of difunctionally terminated (any end groups other than SiOH) polysiloxanes via equilibration polymerisations. In such a case, the problem arises: as to whether the obtained functionalised polymers also contain silanol end groups. To the best of our knowledge, the only direct and the most precise analytical procedure to clarify this question is the Karl Fischer titration/determination of SiOH groups. This determination was performed on a model system consisting of trimethylsilyl terminated polysiloxanes, and it was shown that the obtained polymers contained no SiOH groups.