Characterization of Hydrogen Bonding in Cellulose-Synthetic Polymer Blend Systems with Regioselectively Substituted Methylcellulose

Specifically substituted O-methylcelluloses, 2,3-di-O-methylcellulose and 6-O-methylcellulose (parts B and C of Figure 1, respectively), were used as cellulosic components in blends with poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA). Since their hydroxyl groups (OH) form controlled intra-and intermolecular hydrogen bonds, the cellulose derivatives are useful as model compounds to investigate the effect of hydrogen bonding in cellulose-synthetic polymer blend systems. FTIR (Fourier transform infrared spectroscopy) spectra of the cellulosic-PEO blend films revealed that, while the primary hydroxyl groups at the C-6 position of cellulose interact strongly with ether oxygen in PEO, the secondary hydroxyl groups at the C-2 and C-3 positions show no evidence for polymer-polymer interactions. In the cellulosic-PVA blend films the FTIR analyses suggested that the secondary hydroxyl groups between the cellulose and the PVA were engaged in hydrogen bonds, and, in addition, a hydrogen bond between the anhydroglucose ring oxygen (O-5) of the cellulose and the hydroxyl groups of the PVA was formed. Thus, these results showed the specific regiochemistry of hydroxyl groups in cellulose and its importance to the study of the miscibility in cellulose-synthetic polymer blends.