title: The effect of pressure on cation-cellulose interactions in cellulose/ionic liquid mixtures.
abstract: Cation-cellulose interactions in binary mixtures of [EMIM][OAc] and cellulose have been investigated using high-pressure infrared spectroscopy. At low concentrations of cellulose, almost no changes were observed in the imidazolium C(2)-H frequency; on the other hand, at high concentrations of cellulose, increases in the C(2)-H vibration frequency were observed under ambient pressure. As the pressure was elevated, the imidazolium C(2)-H absorption of the [EMIM][OAc]/cellulose mixtures underwent band-narrowing and blue-shifts in the frequency. These observations suggest that high pressures may strengthen the hydrogen bonds formed between C(2)-H and cellulose, possibly forcing the cellulose to dissociate clusters of ionic liquid through enhanced cation-cellulose interactions. In contrast to the cation-cellulose interaction results, the COO(-) absorption of the anion does not show dramatic changes under high pressures. Our results indicate the possibility of enhanced cation-cellulose interactions through pressure elevation, demonstrating that high pressures may have the potential to tune the relative contributions of cation-cellulose and anion-cellulose interactions in cellulose/ionic liquid mixtures.
authors.affiliation: Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan. hcchang@mail.ndhu.edu.tw.
authors.forename: Hai-Chou
authors.initials: HC
authors.lastname: Chang
authors.forename: Rong-Lin
authors.initials: RL
authors.lastname: Zhang
authors.forename: Ding-Tsai
authors.initials: DT
authors.lastname: Hsu