Solvent-responsive behavior of inclusion complexes between amylose and polytetrahydrofuran

Highly crystalline amylose-polytetrahydrofuran (PTHF) complexes can be obtained by employing organic solvents as washing agents after complex formation. The X-ray diffraction (XRD) of the washed complexes appear sharp at 12.9°-13.2° and 19.6°-20.1°, clear signs of the presence of V6I -amylose. Other diffraction peaks correlate with V6II -amylose, which indicates that the complexed amylose helices are in the form of an intermediate or a mixture of V6I - and V6II -amylose. SEM imaging reveals that the amylose-PTHF complexes crystallize in the form of lamellae, which aggregate in a round shape on top of one another with a diameter around 4-8 μm. Some lamellas aggregate as flower-like or flat-surface spherulitic crystals. There is a visible matrix in between the aggregated lamellas which shows that a part of the amylose-PTHF complexes is amorphous.