Study of the inclusion compounds formed between α-cyclodextrin and high molecular weight poly(ethylene oxide) and poly(ε-caprolactone)

We report the formation of high molecular weight polymer inclusion compounds (ICs) between cr-cyclodextrin and poly(ethylene oxide) (PEO) (M-n = 100 kg mol(-1)), and poly(epsilon-caprolactone) (PCL) (M-n = 40 kg mol(-1)). Both high molecular weight polymer ICs were successfully made by ultrasonic and heating techniques. Dsc, tga, X-ray diffraction, FTi.r. and solid state C-13 n.m.r. were utilized to observe the PCL and PEO polymer chains included inside the channels formed by ol-cyclodextrin. Dsc and tga scans showed that the high temperature stable polymer-CD-IC samples contain no free crystalline polymer. The much higher decomposition temperatures observed for these polymer-CD-ICs may imply that polymer chains included inside the polymer CD-IC channels can greatly improve cyclodextrin's stability. The polymer-CD-IC's X-ray diffraction patterns were very similar to that of valeric acid-CD-IC, which is confirmed to be a channel crystal structure, and the strong peak for both polymer-CD-ICs at approximately 20.0 degrees (2 theta) may confirm their IC formation. New bands appeared at 1729 cm(-1) for PEO-CD-IC and at 1739 cm(-1) for PCL-CD-IC in their FTi.r. spectra. Both bands were absent from the alpha-cyclodextrin spectrum. In CP/MAS/DD C-13 n.m.r. spectra, single resonances for PEO-CD-IC, which compared with the multiple resonances observed for each carbon type in cr-cyclodextrin, may indicate that or-cyclodextrin adopts a more symmetrical cyclic conformation in the PEO-CD-IC sample, while pure alpha-cyclodextrin assumes a less symmetrical conformation in the crystal when it does not include a guest polymer PEO inside its cavity. A one-pulse C-13 n.m.r. spectrum was observed to identify the resonance peak for PEO inside the PEO-CD-IC. (C) 1998 Elsevier Science Ltd. All rights reserved.