Wood pulp fiber modification by layer-by-layer (LBL) self-assembly of chitosan/carboxymethyl cellulose complex: Confocal microscopy characterization

摘要

Bleached cellulose wood pulp fibers from eucalyptus were modified by layer-by-layer (LbL) self-assembly of chitosan/carboxymethylcellulose (CH/CMC) complex. Pulp fibers modified with 10, 20 and 30 bilayers of CH/CMC were prepared and characterized by scanning electron microscopy (SEM) and by laser scanning confocal microscope (LSCM) using the two-photon absorption technique. CH/CMC complex was also deposited onto glass and regenerated cellulose (cellophane) films in order to evaluate the depositions process. CH/CMC films with up to 2750 nm thickness deposited on glass and cellophane were easily observed by SEM, however the films deposited onto a wood pulp fiber surface were visualized only using the LSCM technique since it is very difficult to observe the interface between CH/CMC and cellulose by SEM. Using confocal microscopy allows a precise characterization of the CH/CMC films, which were observed outside and inside the wood pulp fibers. This result also shows that during LbL processing, the polyelectrolyte solution penetrates very fast inside the hollow fiber leading to a complete surface modification of the fiber. Fibers can be considered as hollow tubes with an inner diameter of the order of 15-20 mu m and external diameter of the order of 25 mu m with a cellulose wall of 5 mu m. (C) 2018 Published by Elsevier B.V.