Synchrotron X-Ray and Neutron Fiber Diffraction Studies of Cellulose Polymorphs

We are determining the precise crystal structures and hydrogen-bonding systems of naturally occurring and processed cellulose polymorphs by fiber diffraction.X-rays are used to determine the positions of carbon and oxygen atoms.Neutrons, in combination with isotopic substitution of labile hydrogen atoms in the fibers by deuterium, are used to determine the positions of hydrogen atoms involved in hydrogen bonding.Methods have been developed for obtaining oriented polycrystalline fibers that diffract X-rays and neutrons to atomic resolution.For the first time, data have been collected from naturally occurring pure cellulose Ia isolated from Glaucocystis (a microalgae) and from pure cellulose Ib, isolated from Tunicate (a sea creature).We have also collected data from the polymorphs resulting from cellulose processing; II (both mercerized and regenerated), III(I) and III(II).