Interactions between cellulose and N-methylmorpholine-N-oxide

Abstract

Cellulose II structure was obtained when cellulose precipitated from NMMO/H2O/cellulose solution by adding excess water. The regenerated cellulose was three times more reactive than that of untreated cellulose in hydrolysis reactions. X-ray diffraction (XRD), C-13 Solid-State Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FTIR) Spectroscopy were used to investigate interactions between N-methylmorpholine-N-oxide (NMMO) and cellulose. Cellulose NMMO solid mixtures were heated to various temperatures and cooled to room temperature. The presence of cellulose in cellulose NMMO solid mixture decreased the NMMO melting point by 80-110 degrees C and hampered NMMO recrystallizing during cooling process. NMMO crystal structure collapsed between 70 and 100 degrees C in cellulose NMMO mixture and became very mobile (liquid like form). Mobile NMMO molecules transformed crystalline cellulose into amorphous cellulose. When the cellulose NMMO mixture was heated to 150 degrees C, cellulose started to replace H2O molecules that hydrogen-bonded to NMMO. Our FTIR spectra results suggest that released H2O molecules exist as both adsorbed H2O molecules on cellulose and unbound H2O molecules that are physically confined in cellulose matrix. (c) 2006 Elsevier Ltd. All rights reserved