title: Light-scattering analysis of native wood holocelluloses totally dissolved in LiCl-DMI solutions: high probability of branched structures in inherent cellulose.
abstract: Three holocelluloses (i.e., cellulose and hemicellulose fractions) are prepared from softwood and hardwood by the Wise method. These holocelluloses completely dissolve in 8% lithium chloride/1,3-dimethyl-2-imidazolidinone (LiCl/DMI) after an ethylenediamine (EDA) pretreatment. After diluting the holocellulose solutions to 1% LiCl/DMI, they are subjected to size-exclusion chromatography/multiangle laser-light scattering/photodiode array (SEC-MALLS-PDA) analysis. All holocelluloses exhibit bimodal molecular weight distributions primarily due to high-molecular-weight (HMW) cellulose and low-molecular-weight hemicellulose fractions. Plots of molecular weight vs root-mean-square radius obtained by SEC-MALLS analysis revealed that all the wood celluloses comprise dense conformations in 1% LiCl/DMI. In contrast, bacterial cellulose, which was used as a pure cellulose model, has a random coil conformation as a linear polymer. These results show that both softwood and hardwood HMW celluloses contain branched structures, which are probably present on crystalline cellulose microfibril surfaces. These results are consistent with those obtained by permethylation analysis of wood celluloses.
authors.affiliation: Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Mako
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Ryota
authors.initials: R
authors.lastname: Kuramae
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yanagisawa
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ishii
authors.forename: Akira
authors.initials: A
authors.lastname: Isogai
mesh_terms: D002236:Carbohydrate Conformation; D002241:Carbohydrates / Q000737:chemistry; D002482:Cellulose / Q000737:chemistry* / Q000648:ultrastructure; D032485:Cryptomeria / Q000737:chemistry; D005029:Ethylenediamines / Q000737:chemistry; D005052:Eucalyptus / Q000737:chemistry; D029964:Fagus / Q000737:chemistry; D048289:Imidazolidines / Q000737:chemistry; D007834:Lasers; D008027:Light; D018021:Lithium Chloride / Q000737:chemistry*; D008970:Molecular Weight; D012542:Scattering, Radiation; D012997:Solvents / Q000737:chemistry*; D014934:Wood / Q000737:chemistry* / Q000648:ultrastructure; D014961:X-Ray Diffraction
chemical_list: D002241:Carbohydrates; D005029:Ethylenediamines; D048289:Imidazolidines; D012997:Solvents; C031234:ethylenediamine; D002482:Cellulose; D018021:Lithium Chloride