Thermoplastic elastomers (TPEs) are materials combining the processability of thermoplastics and the elasticity of rubbers. The global value and demand of TPEs is expected to grow in coming years, and advancement in synthetic chemistry is the key driving force. This contribution provides a simple synthesis of high−ethylene EPDMs with high molecular weight, narrow molecular weight distribution (1.9 < M w /M n < 2.3), and properties which can be adjusted from soft thermoplastic to elastomer. EPDMs are prepared through the terpolymerization of ethylene with propylene and 5ethylidene-2-norbornene (ENB), where ethylene is continuously supplied to the reaction bath, while 2 propylene and ENB are added only at the beginning. Polymerizations are catalyzed by three known imido vanadium(IV), differing in the imido substituents and coligand, in combination with Et 2 AlCl and Cl 3 CCO 2 Et. The obtained EPDMs are a mixture of macromolecules each of them featuring a non random comonomer distribution, and non uniform composition. Each chain likely contains multiblocks where the comonomers are segmented, i.e., blocks with high ethylene content that may crystallize, and blocks with high propylene and ENB content that may not crystallize. This broad chemical composition distribution is due to time drift that occurs during the polymerization, which in turn depends on the experimental conditions and ligand set. Composition drift causes variation in the instantaneous feed comonomer ratio, and hence in the chemical composition of the terpolymer over the period of conversion. In proper experimental conditions, EPDMs behave as TPEs without the need of vulcanization, polymer blending, and reinforcement through the addition of fillers. They exhibit high elongation at break, strain hardening at large deformation, remarkable shape retention properties (up to 76% recovery after 10 cycles at 300%, and about 90% at 410% strain), and remelting processability with no fall in properties for recycle and reuse.atmosphere for 8 h, distilled, and stored over 5Å molecular sieves away from bright light. Ethyltrichloroacetate (ETA, Aldrich, 97%) was dried by stirring over CaH 2 for about 4 h, and then distilled under reduced pressure. Et 2 AlCl (Aldrich) was used as received. ENB (Aldrich, mixture of endo and exo, 99% pure), 1-hexene (Aldrich, 97% pure), and 1-octene (Aldrich, 98% pure) were dried by stirring over CaH 2 for about 4 h, then distilled under reduced pressure and, finally, stored under dry nitrogen and kept at -30 °C. The synthesis of imido V(IV) complexes, hereinafter referred as 1a, 2a and 2b, is reported in our previous work. 35,36 Polymerization Experiment. Polymerizations were carried out in a 100 mL roundbottomed Schlenk flask containing a stirring bar. Prior to starting polymerization, the reactor was heated to 110 °C under vacuum for 1 h, and backfilled with nitrogen. The typical reaction procedure for ethylene/propylene/ENB terpolymerization is as follows. Toluene, the appropriate amount of propylene (as a toluene solution), ENB, ...