title: Cellulose Solubility in Ionic Liquid Mixtures: Temperature, Cosolvent, and Antisolvent Effects.
abstract: Select ionic liquids (ILs) dissolve significant quantities of cellulose through disruption and solvation of inter- and intramolecular hydrogen bonds. In this study, thermodynamic solid-liquid equilibrium was measured with microcrystalline cellulose in a model IL, 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIm][DEP]) and mixtures with protic antisolvents and aprotic cosolvents between 40 and 120 °C. The solubility of cellulose in pure [EMIm][DEP] exhibits an asymptotic maximum of approximately 20 mass % above 100 °C. Solubility studies conducted on antisolvent mixtures with [EMIm][DEP] and [BMIm][Cl] indicate that protic solvents, ethanol, methanol, and water, significantly reduce the cellulose capacity of IL mixtures by 38-100% even at small antisolvent loadings (<5 mass %). Alternatively, IL-aprotic cosolvent (dimethyl sulfoxide, dimethylformamide, and 1,3-dimethyl-2-imidazolidinone) mixtures at mass ratios up to 1:1 enhance cellulose dissolution by 20-60% compared to pure [EMIm][DEP] at select temperatures. Interactions between the IL and molecular solvents were investigated by Kamlet-Taft solvatochromic analysis, FTIR, and NMR spectroscopy. The results indicate that preferential solvation of the IL cation and anion by co- and antisolvents impact the ability of IL ions to interact with cellulose thus affecting the cellulose dissolution capacity of IL-solvent mixtures.
authors.affiliation: Department of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States.
authors.forename: David L
authors.initials: DL
authors.lastname: Minnick
authors.affiliation: Department of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States.
authors.forename: Raul A
authors.initials: RA
authors.lastname: Flores
authors.affiliation: Department of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: DeStefano
authors.affiliation: Department of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas , Lawrence, Kansas 66045, United States.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Scurto
mesh_terms: D002482:Cellulose / Q000737:chemistry* / Q000378:metabolism; D006860:Hydrogen Bonding; D052578:Ionic Liquids / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D012995:Solubility; D012997:Solvents / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014783:Viscosity
chemical_list: D052578:Ionic Liquids; D012997:Solvents; D002482:Cellulose