Constructing solvent-free inclusion complexes from β-cyclodextrin- and adamantane-terminated polycaprolactones and their mechanical and shape memory properties

In this study β-cyclodextrins (β-CDs) were reacted with 1,6-diisocyanatohexane (HDI) end-capped poly (ε-caprolactone) (PCL) diols (M_n = 10–80 kg/mol) to give access to β-CD terminated PCLs (PCL-CDs). At the same time an adamantine terminated PCL (P2Ad) was synthesized from the reaction of a PCL diol (M_n = 2 kg/mol) with 1-adamantyl isocyanate and an adamantine end-capped hexane (HAd) was prepared from the reaction of HDI with 1-adamantyl amine. Subsequently PCL-CDs and their mixtures with HAd and P2Ad at a 95:5 feeding mass ratio were dissolved in hexafluoroisopropanol and cast into films. The dried films were characterized by means of mechanical property, shape memory, DSC and DMA measurements to reveal their phase-separation mechanism and solvent-free inclusion complexation. It was shown that attaching β-CDs to two ends of PCL diols leads to the new phase-separation morphology in the PCL-CDs matrix making a great contribution to the mechanical and shape memory properties. Adding HAd and P2Ad further enhances the mechanical and shape memory properties evidencing the occurrence of solvent-free inclusion complexation between β-CD and Ad-terminated PCLs.