Regioselective cationization of cellulosic materials using an efficient solvent-minimizing spray-technique

摘要

Cationization of different cellulosic materials was successfully accomplished using an efficient solvent-minimizing spray-technique. The obtained materials were studied and evaluated in regard to reaction efficiency and regioselectivity using 1D and 1H–13C correlated 2D NMR experiments. The high consistencies and temperatures applied using the spray-technique resulted in reagent effective etherifications and shorter reaction times. The NMR spectra indicated that the spray-technique favors substitutions at position O-6, showing a regioselectivity of O-6 > O-2 > O-3 for softwood kraft pulp (SKP) and cotton linters. However, cationization of mercerized cellulose and dissolving pulp, using the spray-technique, demonstrated more efficient reactions compared to SKP and cotton, and a regioselectivity of O-6 ≥ O-2 > O-3. Nanocrystalline cellulose showed the lowest reactivity and a regioselectivity of O-6 ≫ O-2 > O-3. In this work we provide information on structure–property relationships and characterization methods for modified polysaccharides, together with a solvent system that is well known industrially and in line with sustainability aspects.