Recently, nanocellulose has been considered as a promising and ideal candidate for the development of high‐performance functional composite materials. Nanocellulose is a kind of biomass nanomaterial that is constructed by cellulose and can be extracted from most plants, some animals, and microorganisms. Its hydroxyl group‐rich surface makes nanocellulose hydrophilic and easily modifiable. Meanwhile, as a polysaccharide‐based material, nanocellulose has proved to be nontoxic, biocompatible, renewable, and degradable. Thus, nanocellulose‐based nontoxic drug carriers, wound coverage and contrast agents have been reported and have shown a great potential application in clinical medical care. On the other hand, as nanocellulose contains a large amount of cellulose crystalline regions, its mechanical strength is extremely high. In addition, because of the capability of nanocellulose to form networks cross‐linked by hydrogen bonds in the suspension/matrix, it has also been widely used as a green reinforcing agent in polymer materials to prepare high‐performance materials.

Nanocellulose mainly consists of three kinds of nanomaterials – cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial nanocellulose (BC). CNC is the pure nano‐sized cellulose monocrystal, and occurs as rod‐like nanoparticle with a highly hydrophilic surface. CNF and BC are nanofibers containing both crystalline and amorphous regions. These three nanomaterials can form networks in liquid medium or matrix via hydrogen bonds or chain entanglements. However, the main problem with these nanomaterials is to keep the balance between the compatibility with the matrix ensuring their dispersibility and the capability to form hydrogen‐bonded network providing high mechanical stiffness. Appropriate surface modification of the nanomaterial would allow the development of stiff materials with interesting functions. On the other hand, CNC itself also has special self‐assembling behavior. The CNCs can form cholesteric liquid crystal phase in aqueous suspensions, and thus can be used to make some interesting optical‐tuning materials and so on. For the abovementioned interesting properties, nanocellulose has drawn much attention and has been given more importance in the development of advanced materials.

Nanocellulose has been profoundly studied and widely applied in the development of high‐performance and functional materials. In this book, Nanocellulose: From Fundamentals to Advanced Materials, we have tried to provide a full overview of the structure and preparation of nanocellulose and its applications.

We first introduce the structure and strategies for the extraction of CNC, CNF, and BC, including physical and chemical approaches. Then, as a fundamental step for the preparation of nanocellulose‐based composites, a variety of approaches for the surface modification of nanocellulose are exposed. The following chapters focus on the current status of nanocellulose‐based nanocomposites and the mechanisms involved in their reinforcing capability; we discuss the applications of these high‐performance nanocomposites. The application of the colloidal characteristics and self‐assembling behavior of CNC for the development of functional nanomaterials is highlighted for their huge potential to make promising optical materials, and so on. Finally, in the last three chapters, the use of nanocellulose for biomedical applications, energy materials and devices, and other high‐value use is introduced.

We are thankful for the contribution of all writers of this book, especially the chief editors Jin Huang, Alain Dufresne, and Ning Lin, who did a lot of work to ensure the high quality of this book. The first and corresponding authors of every chapter, i.e. Xiaozhou Ma, Chunyu Chang, Peter R. Chang, Pei Huang, Min Wu, Muhammad Wajid Ullah, Guang Yang, Ge Zhu, Yuhuan Wang, Yaoyao Chen, Thiago Henrique Silveira Maia, Alessandra de Almeida Lucas, Lin Gan, Shiyu Fu, Yanjie Zhang, Gang Chen, Zhiqiang Fang, Ruitao Cha, and Xingyu Jiang (according to the order of the chapters), and all the other coauthors have also provided their input in different areas to successfully complete this book. We also thank Muhammad Wajid Ullah for his great proofreading work during the preparation of this book.

Lastly, we thank the grant of the National Natural Science Foundation of China (51373131, 51873164, 51603171, 31570569, 51733009, 21574050, 31700508, 21774039, and 21875050), and the Talent Project of Southwest University (SWU115034).