Structure and dynamics of a vinylidene fluoride oligomer and its cyclodextrin inclusion compounds as studied by solid-state 19F MAS and 1H → 19F CP/MAS NMR spectroscopy

Abstract

The molecular structure and dynamics of a vinylidene fluoride oligomer telomerized by carbon tetrachloride (Cl-OVDF) and its inclusion compound (IC) with β-cyclodextrin (β-CD) have been investigated using solid-state 19F magic angle spinning (MAS) and 1H→19F cross-polarization (CP)/MAS NMR spectroscopy. The preferential IC formation of the lower-molecular-weight components with β-CD was used to refine as-received Cl-OVDF. The refined Cl-OVDF with larger molecular weight readily takes γ-form (tttg+tttg−) conformation, and it also forms ICs with β-CD (Cl-OVDF/β-CD IC) under a certain condition. 19F MAS NMR indicates that Cl-OVDF chains virtually isolated in the β-CD cavities take no specific conformations even at −40°C. The temperature dependence of the magnetic relaxation times (T1F, T1ρF) indicates that the Cl-OVDF chains in ICs undergo molecular motions similar to the amorphous phase in the bulk, although the intramolecular spin diffusion among 19F nuclei is more significant in the former because of the one-dimensional confinement.