Structural Analysis of Uniaxially Oriented Polysaccharide Films under Humidity Conditioning

The uniaxial oriented films were obtained by drying a highly viscous polysaccharide aqueous solution in a limited space. The molecules were arranged along the contact line of the solid-gas-liquid interface. Such alignment film fabrication technology is expected to lead to the development of sustainable materials that have both biocompatibility and environmental adaptability. For this purpose, it is significant to clarify the interaction between the oriented films and water molecules. In this study, we carried out IR spectroscopy and microscopy to understand structural change of uniaxially oriented films under humidity control. We focused on the synchrotron FT-IR spectroscopy. The spectra from the enol form in the amorphous oriented polysaccharide films depend on humidity, while the spectra were independent of humidity in the case of crystalline polysaccharide films. The results suggest that the processes of both water absorption and dehydration occur on the surface of the uniaxially amorphous oriented film. Therefore, the structural change of the amorphous polysaccharide film is greatly affected by humidity, but the crystalline polysaccharide film is not so affected.