Investigations on interactions between titanium alkoxides and α,ω-dihydroxy PDMS by a combination of rheology and spectroscopy

摘要

The phenomena involved in the reactions between α-ω-dihydroxy PDMS and titanium tetraalkoxides, Ti(OR)_4, were investigated by a combination of rheology and spectroscopy (NMR, IR). The increase of viscosity observed mainly originates from a linear chain extension of PDMS chains by formation of TiAOASi bonds. This is mainly related to an apparent functionality of 2 of Ti(OR)_4. The products formed evolve with time and are sensitive to hydrolysis due to the poor stability of TiAOASi bonds. The precise understanding of the reactions involved raises interesting perspectives for the crosslinking of α-ω-dihydroxy PDMS and Si(OR)_4 derivatives using titanium tetraalkoxide based catalysts.