In-situ contact angle studies of the release of water displacing agents from capsule filled organic coatings

Protective coatings containing polymer microcapsules loaded with water displacing alkoxysilanes were studied by means of a new apparatus allowing the study of advancing and receding contact angles during the simultaneous stretch forming of the coated substrate. FE-SEM studies were performed after stretch forming to correlate the defect structure with the process of hydrophobization. It could be shown that the incorporation of alkoxysilane loaded polymer capsules into a coating system led to a pronounced hydrophobization of cracks that were formed during the stretching of the sample. The local hydrophobization is assigned to the conversion of alkoxysilanes to polysiloxanes via hydrolysis and condensation which are initiated by the contact of those alkoxysilanes with the aqueous electrolyte during water attack.