## 1 Introduction  
Over the last decade, immense research efforts have been undertaken to implement bio-based monomers as suitable alternative building blocks in polymeric materials [1; 2; 3; 4]. This is mostly driven by the imminent scarcity of fossil resources, as well as the enormous potential to exploit local resources and therefore reduce the dependency on imported fossil fuels. In addition, increased public awareness and the desire to move towards a more sustainable economy also create an incentive to find material solutions from renewable resources. However, besides the sustainability aspect, novel bio-based building blocks may also exhibit unprecedented structural features that are not economically accessible from petrochemical feedstock. This, in turn, can lead to new materials with improved properties.  
Itaconic acid (IA), also known as methylene succinic acid, has drawn considerable attention in this context over the last few years [5]. This unsaturated dicarboxylic acid is commercially available in larger quantities (>80.000 t/a) at a competitive price (<2 \(\epsilon\)/kg). It is biotechnologically produced by fermentation of sugar or molasses with the fungi aspergillus terreus [6; 7; 8]. The three functional groups allow for the exploitation of itaconic acid in several different chemical transformations to obtain novel monomeric structures. As far as polymer chemistry is concerned, mainly two different classes of polymers derived from itaconic have been intensively studied. The \(\alpha,\beta\)-unsaturated double bonds, allows for radical polymerization reactions, which has been exploited in several homopolymers and co-polymers of itaconic acid with a range of applications [9; 10; 11; 12; 13]. As a second pathway, the two carboxylic acid groups allow for polycondensation reactions to obtain polyesters [14; 15; 16; 17; 18; 19; 20]. These have been used as reactive binder resins for coatings, shape-memory materials, printing inks, etc. [21; 22; 23; 24; 25]. In addition, these polyesters have been exploited in post-polymerization modification reactions to obtain new polymeric structures [26; 27; 28; 29].  
However, to date, no examples of unsaturated poly(ester amide)s based on itaconic acid have been reported. This is mostly due to the fact that the synthesis of these polyester amides is by no means straightforward. The biggest challenge during a standard polycondensation reaction is the nucleophilic attack of the diamine at the \(\alpha,\beta\)-unsaturated double bond. This aza-Michael addition was first reported by [PERSON] et al. in 1950, and it was shown that subsequently leads to the formation of pyrrolone rings (Scheme 1). [30] Later, this ring-closing reaction was exploited for the synthesis of several bio-based polyamides [31] and poly(ester amides). [32] However, polymers of this type cannot be utilized in radical curing reactions, as the aza-Michael addition results in complete consumption of the unsaturated double bond.  
Therefore, more sophisticated synthetic procedures have to be developed in order to synthesize poly(ester amide)s derived from itaconic acid without the consumption of the unsaturated double bond. This class of unsaturated polymers is of high interest as the amide groups can have a considerable impact on the properties of the materials before and after curing. Herein, two different synthetic strategies are presented that allow for the synthesis of unsaturated aliphatic poly(ester amide)s from itaconic. To the best of our knowledge, this is the first example of this kind of polymeric resins. In addition, the materials are characterized and examined on their suitability to be utilized as UV-curing polymers in coating applications.