Abstract A first attempt was made to produce novel ABC triblock terpolymers with three potentially crystallisable blocks: polyethylene (PE), poly(ethylene oxide) (PEO), and poly(ε‐caprolactone) (PCL). Polybutadiene‐ b ‐poly(ethylene oxide) diblock copolymers were synthesized by living anionic polymerization. Then, a non‐catalyzed thermal polymerization of ε‐caprolactone from the hydroxyl end group of the PB‐ b ‐PEO diblock precursors was performed. Finally, hydrogenation by Wilkinson catalyst produced PE‐ b ‐PEO‐ b ‐PCL triblock terpolymers. Side reactions were detected that lead to the formation of undesired PCL‐ b ‐PEO diblock copolymers, however, these impurities were successfully removed by purification. A range of triblock terpolymers with PCL and PEO minor components were prepared. Topological restrictions on the PEO middle block prevented this block from crystallizing while the complex crystallization behavior of the PE and PCL blocks was documented by DSC and WAXS measurements.