Macromolecular Hydrodynamics and Fractal Structures of the Lignins of Fir Wood and Oat Husks.

The topological structure of the macromolecules of lignins isolated from oat husk and fir wood was studied by means of macromolecular hydrodynamic methods. The macromolecular properties were analyzed by evaluating the intrinsic viscosity and coefficients of the translational diffusion and the sedimentation velocity of the lignins in dilute dimethylformamide solutions. The average molecular weights (MDη) and polydispersity parameters were calculated based on the results of the fractionation, as follows: Mw = 14.6 × 103, Mn = 9.0, and Mw/Mn = 1.62 for lignins from fir wood and Mw = 14.9 Mn = 13.5 and Mw/Mn = 1.1 for lignins from oat husks. The fractal analysis of the lignin macromolecules allowed us to identify the distinctive characteristics of the fractal and topological structures of these lignins. The measurements indicated that the fractal dimension (df) values of the guaiacyl-syringyl lignins from oat husks were between 1.71 and 1.85, while the df of a typical guaiacyl lignin from fir wood was ~2.3. Thus, we determined that the lignin macromolecules of oat husks belong to the diffusion-limited aggregation-type cluster-cluster class of fractals of the Meakin-Kolb type, with a predominance of characteristics common to a linear configuration. The lignins of softwood fir trees exhibited a branched topological structure, and they belong to the diffusion-limited aggregation-type particle-cluster class of fractals of the Witten-Sander type. Lignins from oat husks have the linear topology of macromolecules while the macromolecules of the lignins from fir wood can be characterized as highly branched polymers.

Water stable colloidal lignin-PVP particles prepared by electrospray.

In this study, electrospray deposition has been used as a method to prepare lignin submicron spherical particles. Regularities of electrospraying of lignin solutions in DMSO were revealed. The influence of voltage, distance between electrodes, feed rate, temperature and concentration of lignin solution on the morphology, size and polydispersity of the obtained particles was determined. SEM, IR, TG-DSC, elemental analysis, dynamic light scattering, Zeta potential and nitrogen sorption were used to characterize the particles and to determine their properties. The aqueous colloidal solutions of the submicron particles of lignins from various plant sources were stabilized by preparing the lignin/polyvinylpyrrolidone polymeric complexes.

Characteristics of chemical structure of lignin biopolymer from Araucaria relict plant. Questions and answers of evolution.

New details of chemical structure of Araucaria lignin are the focus of this paper, since Araucaria is a relict plant which fossils are dated by the Permian period. Quantitative chemical analysis, FTIR, EPR and 2D NMR spectroscopies, Py-GC/MS and nitrobenzene oxidation have been used to characterize the Araucaria lignin. This work highlighted the structural features of the lignin of Araucaria, which distinguish it from modern coniferous (gymnosperm) lignins. This lignin exhibits pronounced paramagnetic properties with the concentration of paramagnetic centers of 3.0 × 1017 spin/g, the value of g-factor of 2.0036 corresponds to the phenoxyl radical. The Araucaria lignin is apparently unique since it does not belong to the known G, GS or GSH types. For the first time it was quantitatively proven that he lignin of Araucaria was assigned to compositionally heterogeneous GH lignins, which is not typical for modern lignins.

In vitro adsorption-desorption of aflatoxin B1 on Pepper's lignins isolated from grassy plants.

The aflatoxin B1 (AFB1) adsorption properties of several lignins isolated by the Pepper's method from grassy plants: Helianthus tuberosus (LS-1), Atriplex patula (LS-2), Rhododendron tomentosum (LS-3), Althaea officinalis (LS-4), Lavatera (LS-5), and from wood of spruce Pícea (LS-6) were studied. The adsorption was conducted in vitro in the modeled conditions of the gastrointestinal tract. The correlations between the values of adsorption-desorption and the parameters of surface-porous structure and chemical structure of the lignins were established. The relationships between the adsorption capacity and properties of the lignins led us to the conclusion that chemisorption play the most important role in the strong adsorption of aflatoxin B1. The contribution of the surface physical properties to the process of adsorption of aflotoxin B1 was not significant. It was shown that the sample of lignin isolated from stems of Althaea officinalis, was characterized by the highest value of strong adsorption of aflatoxin B1.

Comparative study of chemical and topological structure of macromolecules of lignins of birch (Betula verrucosa) and apple (Malus domestica) wood.

Recent advances in investigations of chemical structure of lignin give rise to questions about relationship between chemical structure and topology of the macromolecules. In this paper, we made a comparison of results of the studies of chemical and topological structures of lignins. The features of topological structure of lignins of birch and apple wood were identified on the basis of the study of dilute solutions of the lignins by the sedimentation-diffusion analysis and viscometry. The number of branches of macromolecules in the birch and apple lignins was calculated by the Zimm-Kilb equation. Quantitative characteristics of chemical structure of the lignins were obtained by 2D NMR spectroscopy and nitrobenzene oxidation. The structural analysis and the calculations based on the hydrodynamic data gave estimation of the degree of branching of macromolecules, which fit well in the theory on the role of dibenzodioxocin and 4'-O-5 structures in branching of lignin macromolecules.