Cellulose dissolution and regeneration using a non-aqueous, non-stoichiometric protic ionic liquid system
Laura Berga, Isobel Bruce, Thomas W. J. Nicol, Ashley J. Holding, Noriyuki Isobe, Seishi Shimizu, Adam J. Walker, Joshua E. S. J. Reid
Abstract
Abstract The solubility of cellulose has been studied as a function of composition in the binary mixture of 1,1,3,3-tetramethylguanidine and propionic acid. In amine-rich compositions, greater quantities of cellulose can be dissolved than in the equimolar composition, a.k.a. the protic ionic liquid [TMGH][OPr]. By applying a methodology of a short period of heating followed by cooling, similar concentrations of cellulose can be achieved in a much shorter time period. Finally, regeneration of cellulose from solution can be achieved by altering the acid:amine molar ratio. In comparison to cellulose regenerated from these solutions using water as an antisolvent, cellulose regenerated with propionic acid exhibit a lower crystallinity as inferred from x-ray diffractometry, but a greater average molecular weight as inferred from gel permeation chromatography.