Fig. 3: Distribution of regenerated cellulose at the bonding interface.

a Schematic illustration of the preparation of cationic pulp. The green curve represents pulp fiber. Surface hydroxyl groups (–OH, blue spheres) are partially substituted by trimethylammonium chloride functional groups (pink spheres). b Photograph of pulp and cationic pulp with a solid content of 2 wt.%. c ATR-FTIR spectra of pulp (green) and cationic pulp (pink). d Partial delignification of wood bonded with cationic pulp-ionic liquid solution. e Raman spectra from the cell wall of bulk wood (purple) and the lumen region at the bonding interface (pink). f Raman mapping on the transverse section of the bonding interface reveals the distribution of regenerated cationic cellulose between different types of wood tracheids. The colored map demonstrates the integration of Raman bands from 755–780 cm⁻¹, corresponding to the peak area of 764 cm⁻¹.