Novel bis end-capped ethoxysilylpropyl-thioureido-fuctionalised PDMS precursor was synthesised. Addition of trisilanol-heptaisooctyl-POSS increased protective efficiency. Extensive IR spectroscopy confirmed hydrolysis and condensation processes. Raman imaging enabled the determination of homogeneity of coatings. In situ Raman spectroelectrochemical measurement was applied.