Fabrication of Inclusion Compounds with Solid Host γ-Cyclodextrins and Water-Soluble Guest Polymers: Inclusion of Poly(<i>N</i>-acylethylenimine)s in γ-Cyclodextrin Channels As Monitored by Solution ¹H NMR

Abstract

We successfully report the formation of poly(N-acylethylenimine)−γ-cyclodextrin inclusion compounds (PNAI-γ-CD ICs). The PNAI-γ-CD ICs were obtained by three techniques: (a) the precipitation of γ-CD in the polymer solution and (b) and (c) the suspension of as-received cage structure γ-CD and γ-CDCS, with a preformed channel structure, respectively, in the polymer solutions. The PNAI-γ-CD ICs were characterized by solid-state FTIR, X-ray, NMR, DSC, and TGA observations. A 1H NMR study was performed in order to follow the kinetics of the inclusion process in solution. The time-dependent inclusion of PNAIs with different molecular weights by suspension of either as-received cage structure γ-CD or channel structure γ-CDCS in the PNAI solutions was monitored with 1H NMR. Acetone, a nonsolvent for γ-CD, was used as the solvent for the PNAI solutions. Some aspects regarding the role water plays in the polymer inclusion process are revealed from our temporal observations of the inclusion of PNAI guests into solid host γ-CDs.