Sustainable, rigid imide building blocks as promising substitutes for phthalic anhydride in alkyd resins

New, highly rigid bio-based building blocks were synthesized from renewable raw materials. In a first reaction step, an imide was made from citraconic anhydride and the amino acid glycine. This imide was subsequently reacted with sorbic acid using Diels-Alder chemistry, furnishing a double-ring structure. This new, very rigid renewable building block was then incorporated into alkyd resins by standard polycondensation chemistry and technology. The resulting, >80 wt% renewable, alkyd resins were evaluated as white paints in a preliminary way by solvent casting from xylene. The properties of the renewable coatings look promising, some even outperforming those of standard commercial alkyd resins. For further enhancing the sustainability of the systems discussed, turning these highly bio-based alkyd resins into stable aqueous emulsions is a must. (c) 2020 Society of Chemical Industry