Investigations on interactions between titanium alkoxides and alpha,omega-dihydroxy PDMS by a combination of rheology and spectroscopy
Résumé
The phenomena involved in the reactions between alpha-omega-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 Ti-O-Si 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 Ti-O Si bonds. The precise understanding of the reactions involved raises interesting perspectives for the crosslinking of alpha-omega-dihydroxy PDMS and Si(OR)(4) derivatives using titanium tetraalkoxide based catalysts.