Phosphonated and methacrylated biobased cardanol monomer: Synthesis, characterization and application

Abstract

To create an effective adhesion promotion for different surfaces, specific anchor groups are necessary such as phosphonic groups for metals. Biobased phosphorylated monomer from cardanol was synthesized and polymerized by UV curing or miniemulsion radical polymerization. Phosphonic ethoxy cardanol methacrylate (CMP) was synthesized from cardanol via hydroxyethylation, followed by phosphorylation radical addition of dimethyl phosphite onto the unsaturations of the C15 aliphatic chain of cardanol prior methacrylation of the hydroxyl ethoxy group. Lastly the cleavage of the phosphonate ester groups was made to generate the targeted phosphonic acid moieties as adhesion promoters. Moreover, the development of a phosphonic latex was successfully achieved by miniemulsion radical copolymerization in water with an additional redox termination to ensure quantitative monomer conversions. Phosphonic cardanol and cardanol (as reference) latexes were characterized by dynamic light scattering. The effects of cardanol derivatives on the performance of protective coatings on steel plates were evaluated in UV-cured coatings as well as in latex coatings in terms of contact angle and adhesion effectiveness. In coatings, increased hydrophobic properties were observed in fomulations containing free cardanol or cardanol methacrylate. On the other side, the incorporation of phosphonic acid groups onto cardanol significantly improved the adhesion effectiveness of the coating, whatever the film-making technique.