Dynamics of Isolated Polycaprolactone Chains in Their Inclusion Complexes with Cyclodextrins

Solid-state carbon NMR with magic-angle spinning has been used to study the structure and dynamics of semicrystalline polycaprolactone (PCL) and its inclusion complexes formed with α- and γ-cyclodextrins (α- and γ-CDs), which are shown to have channel structures occupied by single and two parallel, side-by-side chains, respectively. Guest−host magnetization exchange has been observed, but the results differ substantially from those observed in semicrystalline polymers and blends. The conventional relaxation experiments and 2D wide-line separation NMR with windowless isotropic mixing have been used to measure the chain dynamics. The results suggest that the intermolecular interactions restrict the dynamics of some atoms more than others, but that the chains in the complex are more mobile than in semicrystalline PCL. These results are compared with the inclusion compound formed between the model compound valeric acid and α-CD that is also a channel complex structure.