INTERACTION OF POLYURETHANE MONOMERS WITH THE LIGNIN OF BIO-MODIFIABLE FLAX FIBER: INVESTIGATION OF THE COPOLYMERIZATION MECHANISM

The revival of interest in lignin chemistry is due to the development of methods for obtaining nanodispersed forms of polymer, the expansion of areas for their practical application and the variety of possible methods of targeted functionalization to give the product new useful properties. Our interests include solving problems related to increasing the moisture resistance of composite materials reinforced with natural fibers. A perspective version for biochemical modification of flax fiber involves defragmentation of interfiber lignifications in the structure of the bast fibre bundle and the use of lignin nanoparticles to block the capillary system in the fiber cell wall. We assume that this is possible as a result of the copolymerization of nanolignin and polyurethane dispersion with the formation of cross-linking between cellulose macromolecules in the fiber pores. The aim of the work is to identify the nature of interactions between polymers using FT-IR spectroscopy and decomposition of integral absorption bands. We model the processes and investigate the change in the state of flax lignin during thermoinitiated reductive depolymerization in a xylose solution, as well when conducting of redox-transformations in the presence of polyurethane dispersion Aquapol 12. The specificity of transformations in modified lignin preparations is characterized by the results of a quantitative assessment of changes in the intensity of 29 bands for the main types of vibrations in interatomic bonds. The results of the analysis argue our conclusions about the completeness of the restoration of multiple bonds in the modified polymer and the rupture of the ether bond between phenylpropane structural units with an increase in the content of units in the oxyaryl form. A set of consistent data on changes in the state of a number of functional groupings in a bicomponent sample indicates that the lignin redox-transformation processes with the participation of reducing sugars create the necessary conditions for interactions between the oxyaryl units of nanolignin and polyurethane dispersion by the Mannich reaction. For citation: Aleeva S.V., Shipova S.E., Shammut Yu.A., Koksharov S.A. Interaction of polyurethane monomers with the lignin of bio-modifiable flax fiber: investigation of the copolymerization mechanism. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2026. V. 69. N 3. P. 105-116. DOI: 10.6060/ivkkt.20266903.7282.