With the growing demand for eco-designed surface technologies, self-stratifying coatings emerge as a sustainable and efficient alternative to conventional multilayer systems. These systems, based on one-pot formulations of incompatible polymers, enable the spontaneous formation of functional multilayer architectures in a single application and curing step, reducing raw material use, energy consumption, and processing complexity [1]. These last years, we designed self-stratifying systems for different applications, such as flame retardancy [2], fouling resistance and aerospace [3]. They were mainly based on oil-based and bio-based epoxies [4] combined with different polymers such as polyurethane, silicone and PVDF. A comparative Life Cycle Assessment (LCA) revealed a significant reduction in environmental impact - up to 30% compared to traditional multilayer systems - due to the simplified processing and bio-based content [5].

Our research now focuses on self-stratifying coatings that incorporate dynamic covalent polymer networks, i.e. vitrimers. Two original self-stratifying coatings were designed, i.e. a bio-based vitrimer expoy/PVDF system [6] and a bio-based epoxy / vitrimer silicone system [7]. The first one demonstrates robust adhesion to metallic substrates, along with thermally triggered removability, allowing substrate recovery and potential material recyclability. The second shows excellent adhesion to plastics and self-repairing properties at room temperature.

This study paves the way for new generations of coatings combining sustainability, high performance, and smart functionalities, with promising applications in packaging, food processing, electronics, and aerospace sectors.

The effectiveness of intumescent paints, applied on different kind of substrates such as steel, wood and composites, has been extensively proven in various fields like building, transportation. Upon fire exposure, these protective paints containing 30 to 50 wt.% of flame retardant additives decompose leading to the development of an insulating expanded multicellular carbon structure [1]. Epoxy thermoset is one of the binders commonly used for such paints but it exhibits some limitations including maintenance issues following damage (impacts, scratches...) and end-of-life management limited by the lack of solution for separating the paint from the substrate. 

To tackle these issues, a promising strategy could be to use stimuli responsive binders such as covalent adaptative networks and particularly vitrimers. Vitrimers are able to change their topology by thermal activation of associative bond exchange reactions imparting them intrinsic recycling and healing abilities [2]. The development of an intumescent vitrimer coatings is however not straightforward since the high additives loading used in such coatings could impart the dynamic properties. In the literature, only few articles have investigated the impact of the presence of nanoparticles [3-8] or microsize additives [9] on the dynamic of the vitrimer matrix. 

In this study, we evaluate the potential of using epoxy vitrimer binders to replace the thermoset one in a classical intumescent paint formulation containing 50 wt. % of additives. Particular emphasis is given on the trade-off between fire and mechanical performances, as well as the processability and the dynamic properties of the network. We demonstrated in this work, the elaboration of an intumescent vitrimer coating exhibiting satisfying fire performances with dynamic kinetics of bond exchange reactions which could be further improved.