In this project, linear SMPUs were synthesized from high molecular weight PCL, 4,4’-methylene diphenyl diisocyanate (MDI), 1,6- Hexanemethylene diisocyanate (HMDI), and PEG. The molecular weight of the samples was determined using a SEC, with broad range retention as function of the composition. The mechanical performance of the SMPUs is affected by the composition and the effect of heating the sample above 120°C. The result of the 1H-NMR spectroscopy supports the PU segmentation for the reaction pathway expected.