As the global demand for sustainable materials continues to grow, high-performance materials based on natural resources have gradually become an important direction for research and industrialization. Among them, nanocellulose (Nanocellulose), as a nanoscale material derived from natural cellulose, has received widespread attention in many industrial fields in recent years due to its excellent physical properties, biocompatibility and renewable characteristics. 1. What is nanocellulose? Nanocellulose is a type of nanostructured material obtained by processing natural cellulose (such as wood pulp, cotton, agricultural waste, etc.) through physical, chemical or enzymatic methods. Its diameter is usually 5–100 nm, and its length can reach hundreds of nanometers to several micrometers. According to different structures and preparation methods, nanocellulose is usually divided into three main types: Cellulose nanofiber (CNF, Cellulose Nanofiber) is obtained through mechanical dissociation and has a long fiber structure and high

1. Basic structural advantages and barrier properties of nanocellulose Nanocellulose (Nanocellulose) is a nanoscale fiber material obtained by dissociating natural cellulose through mechanical methods, TEMPO oxidation or enzymatic processes. It mainly includes cellulose nanofibers (CNF) and cellulose nanocrystals (CNC). Its diameter is usually 5–50 nm, its length can reach several microns, and it has an ultra-high aspect ratio and a highly crystalline structure. The fundamental reason why nanocellulose has excellent barrier properties is: high crystallinity structure - the molecular chains are arranged regularly, making it difficult for gas molecules to penetrate the dense hydrogen bond network - forming a high-density two-dimensional/three-dimensional network structure and high specific surface area - improving the interface interaction and enhancing the density of the composite film 'Tortuous Path Effect' - the gas or water vapor diffusion path is significantly extended. In the dry state, nanofibers

In the context of the rapid development of bio-based materials, bacterial cellulose (BC), as a natural polymer material synthesized by microbial fermentation, is moving from laboratory research to large-scale application. Compared with plant cellulose, bacterial cellulose has significant advantages in purity, microstructure and performance stability, and is an important research direction in the current field of functional materials. 1. The formation mechanism and structural nature of bacterial cellulose. Bacterial cellulose is mainly secreted and synthesized by cellulose-producing bacteria such as Komagataeibacter xylinus under aerobic conditions. Its molecular structure is the same as that of plant cellulose, which is a linear polysaccharide connected by β-1,4-glucosidic bonds, but its formation process is different: bacteria directly polymerize and extrude glucose during the fermentation process to form nanoscale fibers, which are then self-assembled to form a three-dimensional network structure. This 'in-situ nanofabrication