Straightforward Synthetic Protocol to Bio-BasedUnsaturated Poly(ester amide)s from Itaconic Acidwith Thixotropic Behavior.

In the field of polymer chemistry, tremendous efforts have been made over the lastdecade to replace petrochemical monomers with building blocks from renewable resources. In thisrespect, itaconic acid has been used as an alternative to acrylic acid or maleic acid in unsaturatedpolyesters for thermal or UV-curing applications. However, examples of poly(ester amide)s fromitaconic acid are scarce. Under standard polycondensation reactions, the presence of free aminesleads to aza-Michael addition reactions at the α,β-unsaturated double bond of the itaconic acid andisomerization reactions to mesaconic acid. Both reactions make the resulting materials useless asUV-curing polymer resins. To avoid these undesired side reactions, we herein report the use ofpreformed, well-defined diols containing internal amide bonds. The resulting unsaturatedpoly(ester amide) resins were analyzed before and after UV-induced crosslinking. Viscositymeasurements revealed a strong thixotropic behavior induced by the amide groups, which isusually not detected in structurally similar polyester resins.