Hierarchical Structure of Microbial Cellulose and Marvelous Water Uptake, Investigated by Combining Neutron Scattering Instruments at Research Reactor JRR-3, Tokai

We discuss microbial cellulose (MC) produced by Acetobacter Xylinum and its metabolism related to the bacterium body structure on a basis of knowledges obtained by the small-angle scattering method with combining different spectrometers. MC is a supra-molecule system impregnated with a huge amount of water about 99% by weigh. In the previous literature [Eur. Phys. J. E, 2008 and Macromol. Symp. 2009], we elucidated that 90% of total water is accumulated in non-crystalline bundle causing concentration fluctuations. In this paper, we develop our arguments by newly adding the knowledges on (i) the hierarchy in a bacterium body studied by SANS & USANS and (ii) the non-crystalline local structure in as-produced MC in a culture solution, confirmed by neutron diffraction with polarization analyses. As a control to emphasize the peculiarity of MC, we compare MC to a synthetic polymer gel of poly(N-isopropylacrylamide) (PNIPAAm) in a swollen state. Consequently, we conclude that a mechanism of excellent water absorption found for MC is attributed to capillarity related to hierarchically preserved non-crystalline domains, whereas tight hydration onto a monomer unit via a hydrogen bond is crucial to result in high water absorption for the PNIPAAm gel.