Study of cellulose/ethylene diamine/salt systems

To better understand the complex interactions leading to dissolution of cellulose in ethylene diamine (EDA)/salt solvents, studies of interactions in sub systems of solution components and a model system based on cellobiose were conducted. Interaction between EDA and salt cation was investigated through comparison of solvation of K⁺, Na⁺ and Li⁺ in the EDA/H₂O binary solvent system. The least degree of solvation of K⁺ in EDA increased its availability for direct interaction with cellulose. Wide angle X-ray diffraction was utilized to study the interaction between EDA and cellulose. The effect of various solvents on cellulose crystalline polymorph was compared. The results indicated that cellulose was easily accessible to EDA and 1,3-diaminopropane, but was not affected by water or ethanolamine. The effect of salt concentration was investigated using cellobiose as a model compound through HSQC (Heteronuclear Single Quantum Coherence) NMR spectroscopy. Solid state CP/MAS (cross polarization/magic angle spinning) ¹³C NMR spectroscopy was employed to characterize changes in the conformation of the CH₂OH group of cellulose during dissolution. A mechanism scheme of cellulose dissolution in EDA/KSCN systems was proposed based on the information gathered.