Structure-Property Relationships of Cellulose Nanocrystals and Nanofibrils: Implications for the Design and Performance of Nanocomposites and All-Nanocellulose Systems

Cellulose nanocrystals (CNCs) and nanofibrils (CNFs) are sustainable candidates for designing nanocomposites and all-nanocellulose systems for a myriad of advanced applications, such as protective coatings, packaging materials, and hydrogels. The role of nanocellulose in such different applications is mainly determined by its morphological and physicochemical properties. Although these properties have been studied at length by a consistent and growing number of publications, there is still a lack of a comprehensive study of the relationships between structure, properties, and functions of different nanocelluloses. Here, we thoroughly investigated the combined effect of distinct production methods and anatomical origins of non-wood cellulose on the structure-property relationships of CNCs and CNFs. These nanoparticles were obtained by the most established production approaches, that is, sulfuric acid hydrolysis or TEMPO-mediated oxidation/fibrillation of elephant grass leaves or stems, that is, two different parts of a unique biosource. We were able to prepare CNCs and CNFs with modulated morphological features and degrees of polymerization, which implied major effects on the mechanical and rheological behaviors of nanocellulose films and dispersions, respectively. Additionally, tailoring lignin and ionizable group contents as well as the color, transparency, and stability of nanocellulose dispersions could provide important implications for the shelf life of nanocellulose formulations, as well as for their application as nanocomposite additives with UV-protection and antioxidant abilities. Therefore, the assembly of results presented here can work as a tool to guide decision-making for both (1) the selection of methods and/or plant anatomical parts to produce nanocelluloses with tailored properties and (2) the prospects of combining different cellulose nanostructures to design advanced materials.

Automated summary

The study investigated the combined effect of different production methods and anatomical origins of non-wood cellulose on the structure-property relationships of CNCs and CNFs. By adjusting the production methods and origins of cellulose, modulated morphological features and degrees of polymerization were obtained, which significantly influenced the mechanical and rheological behaviors of nanocellulose films and dispersions.