Next-generation super varnishes via reversible de-activation radical polymerization

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Coatings are integral for materials used in the automotive and aerospace industries. In this competitive sector, C&D Aerospace Canada Co. (subsidiary of C&D Zodiac Inc.) considers it vital to develop their own varnish coating formulations: a super varnish. Obvious "must-have" properties include resistance to cracking, prevention of shrinkage, high anti-flammability and adhesion to wood substrates. Further, the coating solution must be amenable to spraying techniques and must have an extended shelf-life. Through our previous interactions, we have developed a formulation that has high resin content (30% be weight) but has very low viscosity, thereby reducing the volatile organic content (VOC). It also combines several properties into one single molecule. In addition to meeting the initial requirements, the next step towards the development of a super varnish would be to develop greener processes with further reduction in VOC (which leads to improved anti-flammability properties) and self-healing characteristics. Greener processes includes not only reduction in VOC via water-borne coating processes, but also incorporating monomers from sustainable resources as much as possible. The use of reversible de-activation radical polymerization (RDRP) enables finer control of microstructure plus the ability to be readily polymerizable in dispersed aqueous systems. Self-healing properties are desirable, as materials that revert and close any surface damage/defect eliminates costly scratch-removal procedures. The application of RDRP to self-healing materials is cutting-edge, with reports only relatively recently highlighting this novel combination. With the incorporation of all these features, engineering of these novel resin coatings (multiple coatings, heat treatments, convective drying) will ensue to optimize material properties and process time, leading to a facile industrial implementation.******