Interchain Hydrogen Bonds in Cellulose-Poly(vinyl alcohol) Characterized by Differential Scanning Calorimetry and Solid-State NMR Analyses Using Cellulose Model Compounds

To characterize the nature of the interchain hydrogen bonds involved in cellulose/PVA blends, DSC and solid-state NMR analyses were carried out on mixtures of two cellulose model compounds (2,3-di-O-methycellulose; 23MC and 6-O-methylcellulose; 6MC) and PVA. The conclusions reached, based on our experimental data, are as follows: first, the thermodynamic data confirms that the interchain hydrogen bonds between the cellulose ring oxygen and the OH group of PVA are favored over bonds formed between the hydroxyl groups on each homopolymer. Second, the proton spin-lattice relaxation time in rotating frames, T_1ρH, showed that both MC/PVA blends examined were homogeneous down to a scale of 17.5 nm or less at most concentrations, suggesting that blends of pure cellulose and PVA may also be miscible on a molecular scale. Finally, we comment on the correlation between the interaction parameter, χ, assessed from thermodynamic data obtained using DSC and the domain size for the hydrogen bonding pairs in the blends.