Photoinduced thiol-ene “click” chemistry for resource-efficient curing of polysilazane-based coatings and its effects on coating property profile

Abstract

Polysilazane-based coatings exhibit excellent mechanical properties and chemical resistance, but thermal curing limits their range of applications. Therefore, the aim of the study was to evaluate the more resource-efficient curing of polyorganosilazane-based coatings on a stainless-steel substrate by photo-induced thiol-ene “click” reaction at room temperature compared to the conventional thermally induced polymerization using a radical initiator. As expected crosslinking at higher temperatures led to the formation of a pronounced Si-O-Si network. However, crosslinking via UV radiation at room temperature suppressed the incorporation of oxygen remarkably also after a subsequent additional treatment at 135 °C in air. Both the chemical stability of the layers cured by means of UV radiation and the mechanical properties are comparable to those of the thermally crosslinked coatings. Therefore, curing using UV radiation at low temperatures is a suitable alternative method for producing protective coatings on substrates with limited thermal stability.

Keywords

• Polysilazane
• Coating
• Thiol-ene “click” reaction
• Photopolymerization