Structural pathways in the treatment of cellulose with amines

Amines act as swelling agents in the treatment and processing of cellulose and cellulosic biomass fibers. They can penetrate and form crystalline complexes with cellulose fibers that, on amine removal, have improved pulping, textile, or chemical reactivity properties. Ammonia treatments have been used to improve the strength and shrink resistance of cotton and regenerated fabrics, and are being explored as pretreatments for biomass to improve its conversion to glucose and biofuels. Ethylenediamine has also been investigated for its use in biomass pulping and pretreatment, and as a component of cellulose solvents. We have been studying the detailed interaction of amines with cellulose using a variety of crystallographic and spectroscopic techniques including neutron and X-ray crystallographic and CP/MAS 13C NMR techniques. We shall describe the detailed crystal structures of the various forms of cellulose associated with amine treatments and discuss possible structural transition pathways between those forms.