Structure-property correlations in hybrid sol-gel coatings as revealed by Raman spectroscopy

It is demonstrated that confocal Raman microscopy is a powerful tool for investigation of the structural evolution in sol-gel derived hybrid polymer films in a non-destructive way. A UV-curable coating based upon vinyl triethoxysilane and tetraethoxysilane as the main constituents was studied as an example. Raman spectra and micro-mechanical measurements were successfully correlated in order to gain insight into light induced cross-linking and photodegradation processes. The data were used to determine the degrees of conversion of vinyl groups and to follow their postcuring behaviour under accelerated weathering. It is also shown that confocal Raman microscopy can be used for the investigation of depth dependent phenomena in hybrid polymer films.