Masahisa Wada 교수

Polymorphs of cellulose I, III(I), and IV(I) have been investigated by X-ray diffraction, FT-IR, and solid-state (13)C NMR spectroscopy. Highly crystalline cellulose III(I) samples were prepared by treating cellulose samples in supercritical ammonia at 140 degrees C for 1 h, and conventional cellulose III(I) samples were prepared by liquid ammonia treatment. The cellulose IV(I) sample of highest crystallinity was that prepared from Cladophora cellulose III(I) in supercritical ammonia, followed b

The crystal and molecular structure, together with the hydrogen-bonding system in ammonia-mercerized cellulose IIII, has been determined using synchrotron X-ray and neutron fiber diffraction data. The structure has a one-chain monoclinic unit cell with an asymmetric unit that contains only one glucosyl residue and with the hydroxymethyl group in the gt conformation. The hydrogen-bonding system is well-defined with no evidence of disorder. A bifurcated hydrogen bond links a donating secondary alc

Abstract A survey by X‐ray diffractometry was carried out to confirm the two crystalline phase Iα/Iβ(triclinic/monoclinic) system of native celluloses. We have investigated cellulose samples from 12 different origins and measured the d ‐spacings with reasonable precision. The samples were then subjected to the hydrothermal annealing that brings the cellulose crystals to the monoclinic type; d ‐spacings were reevaluated afterward. From the statistical analysis using observed d ‐spacings, all the

A supercritical ammonia treatment has been used to trap an ammonia−cellulose complex during the conversion of cellulose I to cellulose IIII. The crystal and molecular structure of this complex, designated ammonia−cellulose I, has been determined by using X-ray fiber diffraction data (space group P21; a = 4.47 Å, b = 8.81 Å, c = 10.34 Å, γ = 92.7°). Although the existence of ammonia−cellulose I has been known for some time, this is the first report of its crystal structure. A one-chain monoclinic

Measurements of the thermal expansion coefficients (TECs) of chitin crystals in the lateral direction are reported. We investigated highly crystalline α chitin from the Paralithodes tendon and an anhydrous form of β chitin from a Lamellibrachia tube from room temperature to 250 °C, using X-ray diffraction at selected temperatures in the heating process. For α chitin, the TECs of the a and b axes were αa = 6.0 × 10−5 °C−1 and αb = 5.7 × 10−5 °C−1, indicating an isotropic thermal expansion in the

Abstract Measurements of the thermal expansion coefficients (TECs) of cellulose crystals in the lateral direction are reported. Oriented films of highly crystalline cellulose I β and III I were prepared and then investigated with X‐ray diffraction at specific temperatures from room temperature to 250 °C during the heating process. Cellulose I β underwent a transition into the high‐temperature phase with the temperature increasing above 220–230 °C; cellulose III I was transformed into cellulose I

Highly crystalline cellulose IIII samples were prepared by subjecting oriented films consisting of an assembly of Cladophora cellulose microcrystals to supercritical ammonia. Diffraction data recorded on these specimens indicated that the crystals of cellulose IIII could be fully described with a one-chain unit cell and a P21 space group, with the cellulose chain axis on one of the 21 screw axes of the cells. The new cell had the following parameters: a = 0.448 nm, b = 0.785 nm, c (chain axis) =

Bio-based polymer is considered as one of potentially renewable materials to reduce the consumption of petroleum resources. We report herein on the one-pot synthesis and development of unnatural-type bio-based polysaccharide, α-1,3-glucan. The synthesis can be achieved by in vitro enzymatic polymerization with GtfJ enzyme, one type of glucosyltransferase, cloned from Streptococcus salivarius ATCC 25975 utilizing sucrose, a renewable feedstock, as a glucose monomer source, via environmentally fri