Eco-efficient, hydrophobic, self-healing and self-stratifying coating for polycarbonate

Environmental sustainability and multifunctionality are now key drivers for smart coatings design and applications. In a circular economy that promotes durable materials, the challenge is to develop multi-functional onepot coating materials. The eco-efficient self-stratification process allows the spontaneous formation of complex polymer multilayers in only one step of formulation, application, and curing. This leads to the simultaneous production of both an undercoat and a finishing coating with all the properties needed to protect a material. In addition, film formation in a single application step drastically reduces adhesion failures and contamination between layers. The original idea in this study was to conceive a self-stratifying and self-healing coating formulation using a bio-based epoxy resin and a PDMS-based vitrimer, by taking advantage of the self-healing properties of the vitrimers. This newly discovered class of polymers possess dynamic covalent bonds. This epoxy resin - dynamic PDMS blend was successfully applied on polycarbonate substrates by spraying and exhibited a type I stratification associated with room temperature self-healing properties. Furthermore, the coating showed great adhesion to the substrate, on the contrary to the dynamic-PDMS when applied directly onto polycarbonate. The stratification was observed with SEM-EDS imaging. The self-healing property was proven by optical microscopy imaging of scratches under different thermal treatments. FT-IR and wet contact angle were used to further characterize the synthetized dyn-PDMS.