Photocontrol of Mechanical Properties of Pulp Fibers and Fiber-to-Fiber Bonds via Self-Assembled Polysaccharide Derivatives

Photoresponsive pulp fibers are prepared by self-assembly of photoactive cationic cellulose derivatives with pulp fibers in aqueous environment. Photoactive groups of the derivatives undergo 2 pi + 2 pi cycloaddition reaction under UV-light irradiation. Fast photocrosslinking leads to the formation of the covalent bonds between the photoactive groups on the fiber surfaces. This results in drastic enhancement of the mechanical properties of the fiber network. Tensile strength and Z-directional tensile strength increase by 81 and 84% compared to the original fiber network. Stiffness of the individual fibers increases by 60%. Such concept of controlling mechanical properties of the fiber materials by the light gives a possibility to design smart bio-based materials and to increase end value of the fiber products.