Combining small-angle and intermediate-angle neutron scattering to study the hierarchical structure in microbial cellulose

摘要

In this study, we employed intermediate angle neutron scattering (IANS) technique to correct the small angle neutron scattering (SANS) data of the water-swollen microbial cellulose (MC) sample, the system of which has a significant incoherent contribution from the water solvent, and we described the effects that the corrections have on the structural analysis. In order to elucidate the structure efficiently, the solvent was exchanged in situ between protonated water and deuterated water to give different scattering contrasts, and the water-exchange processes were followed by time-resolved SANS and IANS simultaneously. Our results showed that: (1) after incoherent correction, the microstructure of MC sample was proved to be invariant with solvents; (2) the scattering intensity depended only on the contrast factor, revealing a two-phase system composed of water-resistant crystalline cellulose phase and hydrated amorphous phase; (3) the cellulose crystallites have a constant scattering length density of 2.0 x 10(10) cm(-2), determined by the matching point at which the scattering contrast between the two phases is minimum. This value was consistent with that of 1.9 x 10(10) cm(-2) estimated from its chemical structure. (C) 2015 Elsevier Ltd. All rights reserved.