Activation of cellulose fiber in ionic liquid media for heterogeneous chemical modification

Naturally occuring and renewable biopolymers have attracted great interest as raw materials for the production of advanced materials, to phase out existing petrochemical-based polymers. Cellulose is a feasible feedstock for cheap, renewable and potentially biodegradable products for mass production. Chemical modifications of the hydroxyl groups of cellulose by etherification, esterification, carbamoylation or redox chemistry provide access to a wide variety of materials with variable properties. Potential large-scale uses of these materials range from films to bulk composites. Recently, Ionic liquids (IL's) have opened new possibilities for homogenous modification of cellulose. ^[1-2] However, we would also like to consider whether IL's could be used to activate cellulosic fiber surfaces for efficient heterogenous modification. In this connection we examined the use of l-ethyl-3- methylimidazolium chloride ([emim]Cl) to promote the heterogeneous modification of cellulose with succinic anhydride (SA). Here, our strategy was to use high concentrations of cellulose to allow for partial swelling of the cellulose fibers, but to avoid complete dissolution. The analysis of the insoluble materials was achieved using microscopy, a laser-light scattering technique (particle size determination), FTIR-ATR and NMR spectroscopy. This allowed not only for thorough characterization of the resulting materials but has also direct assessment of the efficiency of IL's for the purposes of fibre activation, in the production of sustainable cellulose-based materials.