title: Role of solvent parameters in the regeneration of cellulose from ionic liquid solutions.
abstract: The ionic liquids 1-ethyl-3-methylimidazolium acetate [emim]OAc, N,N,N,N-tetramethylguanidium propionate [TMGH]EtCO(2), and N,N,N,N-tetramethylguanidium acetate [TMGH]OAc, and the traditional cellulose solvent N-methylmorpholine N-oxide NMMO were characterized for their Kamlet-Taft (KT) values at several water contents and temperatures. For the ionic liquids and NMMO, thresholds of regeneration of cellulose solutions by water were determined using nephelometry and rheometry. Regeneration from wet IL was found to be asymmetric compared to dissolution into wet IL. KT parameters were found to remain almost constant at temperatures, between 20-100 °C, even at different water contents. Among the KT parameters, the β value was found to change most drastically, with an almost linear decrease upon addition of water. The ability of the mixtures to dissolve cellulose was best explained by the difference β-α (net basicity), rather than β alone. Regeneration of cellulose starts at thresholds values of approximately β < 0.8 (β-α < 0.35) and displayed four phases.
authors.affiliation: Department of Forest Products Technology, Aalto University, P.O. Box 16300, FI-00076 Aalto, Finland.
authors.forename: Lauri K J
authors.initials: LK
authors.lastname: Hauru
authors.forename: Michael
authors.initials: M
authors.lastname: Hummel
authors.forename: Alistair W T
authors.initials: AW
authors.lastname: King
authors.forename: Ilkka
authors.initials: I
authors.lastname: Kilpeläinen
authors.forename: Herbert
authors.initials: H
authors.lastname: Sixta
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry; D006146:Guanidines / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles / Q000737:chemistry*; D052578:Ionic Liquids / Q000737:chemistry*; D009025:Morpholines / Q000737:chemistry; D009391:Nephelometry and Turbidimetry; D012996:Solutions; D012997:Solvents; D013696:Temperature; D014867:Water
chemical_list: D003497:Cyclic N-Oxides; D006146:Guanidines; D007093:Imidazoles; D052578:Ionic Liquids; D009025:Morpholines; D012996:Solutions; D012997:Solvents; D014867:Water; D002482:Cellulose; C067960:4-methylmorpholine N-oxide; C518739:1-ethyl-3-methylimidazolium