The impact of the polycaprolactone content on the properties of polyurethane networks

The influence of soft segment (SS) content on the properties of novel polyurethane networks (PUNs), prepared by a two-step polymerization in a solvent mixture, was investigated in this work. Hyperbranched polyester of the third pseudo generation (BH-30) was used as a crosslinker, and together with isophorone diisocyanate (IPDI) was applied to build hard segments (HS) in PUNs. On the other hand, SS of the prepared PUNs are based on polycaprolactone (PCL). The content of SS in PUNs varied from 10 to 50 wt%. The structural, thermal and mechanical properties, swelling behavior, as well as morphology of PUNs, were explored by various experimental methods. Performed investigations have shown that the use of BH-30 led to the emergence of relatively high crosslinking density and good mechanical properties, and that all features of PUNs significantly depend on the SS content. Higher PCL content caused presence of certain crystallinity, better thermal stability, more pronounced microphase separated morphology, but also lower degree of hydrogen bonding, crosslinking density and storage modulus of the prepared PUNs. The obtained results have shown that the properties of PUNs can be easily varied and customized to different practical needs.