Composition-property relationship of polyurethane networks based on polycaprolactone diol

This work was focused on the synthesis of polyurethane networks (PUNs) based on polycaprolactone (PCL) as soft segment (SS) and Boltorn® aliphatic hyperbranched polyester of the second pseudo generation and 4,4′-diphenylmethane diisocyanate (MDI) as the parts of the hard segments (HS), by a two-step solution polymerization. In order to find the best ratio between HS and SS to achieve good thermal and mechanical properties, suitable hydrophobicity and morphology of the PUNs, various experimental analyses were conducted. The obtained results revealed that features of the PUNs highly depend on the PCL content. The increase in the PCL content leads to the increase in thermal stability, hydrophobicity and appearance of the microphase separation, but on the other side, it also leads to the decrease in storage modulus in the rubbery plateau, crosslinking density and glass transition temperatures of PUNs. This work shows that features of PUNs can be easily adjusted for a specific application by careful selection of the SS and HS ratio.