Revealing the variation in cellulose microfibrilization dynamics in palm fibers and parenchyma cells

The biomacromolecules spatial arrangement and anatomical structure of plant cell wall play a crucial role in influencing the dynamic process of cellulose microfibrilization. In this work, the microfibrilization dynamics in palm fibers and parenchyma cells has been comprehensively and systematically analyzed via morphology, crystallinity, and biomacromolecule orientation characterization. The results indicate significant differences between the two types of palm cells. Specifically, compared to fibers, parenchyma cells have larger lumens and thinner walls, which make them more accessible to reagent contact. Additionally, the biomacromolecule orientation in parenchyma cells is more disordered, which facilitates easier dissociation. These factors lead to the preferential disintegration of the parenchyma cell walls during the palm microfibrillation process. Specifically, after 20 min of ultrasonic treatment, the parenchyma cells were completely disintegrated, whereas the fiber cell walls began to disintegrate only after 60 min of ultrasonic treatment. The differences in microfibrilization dynamics between two types of palm cells can be used to prepare fiber-reinforced aerogels, where parenchyma cells are preferentially disintegrated into nanocellulose, forming the aerogel matrix. Meanwhile, the fibers, which are not fully disintegrated, retain some strength to serve as the mechanical support units of the aerogel.