Surface modification of cellulose nanocrystals towards new materials development

Abstract

Cellulose nanocrystals (CNCs) are a kind of sustainable nanoparticle from biomass, which are widely used as reinforcing filler and assembly building block for high‐performance composites and function materials including biomaterial, optics, and so forth. Here, their unique advantages in material applications were reviewed based on their rod‐like morphology, crystalline structure, dimension‐related effects, and multi‐level order structure. Then, we focused on the molecular engineering of CNCs, including the structure and physicochemical properties of their surface, along with surface modification methods and steric effects. We further discussed the performance‐improvement and functionalization methods based on multi‐component complex systems, together with the effects of surface molecular engineering on the performance and functions. Meanwhile, methods of optimizing orientation in uniaxial arrays were discussed along with those of enhancing photoluminescence efficiency via surface chemical modification and substance coordination. In the end, we prospected the design, development, and construction methods of new CNCs materials.

Nanocellulose-Based Thermoplastic Polyurethane Biocomposites with Shape Memory Effect

“…The presence of reactive hydroxyl groups on the surface of nanocellulose increases the variety of possible modifications [136,137]. As a result, the stability of dispersions improves, and the thermal stability of polyurethane nanomaterials is increased.…”

Research progress on the correlation between properties of nanoparticles and their dispersion states in polymer matrix

“…Therefore, modifying the surfaces of nanoparticles is necessary to accomplish their stable dispersion in the polymer matrix. 55 Common methods include decomposing the organometallic precursors in solution environment and then highquality nanoparticles can be obtained with the surface covered with small molecular alkane-based ligands, alkyl mercaptans, amines, and so forth. 56 However, simple mixing of these nanoparticles covered with alkane and polymers will cause uneven dispersion or aggregation of particles, resulting in reduced composite properties.…”

“…Nanoparticles are in small size, high‐surface energy and thermodynamically unstable, so inorganic nanoparticles will self‐agglomerate in polymers, which make it difficult to accomplish homogenous dispersion of particles in composite systems; especially if the compatibility between particles and polymers is poor, there will be almost no nanoparticles in the polymer. Therefore, modifying the surfaces of nanoparticles is necessary to accomplish their stable dispersion in the polymer matrix 55 . Common methods include decomposing the organometallic precursors in solution environment and then high‐quality nanoparticles can be obtained with the surface covered with small molecular alkane‐based ligands, alkyl mercaptans, amines, and so forth 56 .…”

Effects of Grafting Structure on 1D One-Component Composites: An Example of Surface-Grafted Cellulose Nanofibers

“…36 Fortunately, the hydroxyl groups on the surface of nanocellulose can perform as reaction points for grafting reactions. 37,38 Several reports about applying surface-grafted cellulose nanocrystals (CNC), a type of nanocellulose with a rod-like structure, for the construction of one-component nanocomposites have been published. 39−41 Due to the diversity of nanocellulose sources, grafting methods, and grafted polymer types, it is improper to compare the results of these studies directly, and the reinforcing mechanism was unclear.…”

“…In addition to these inorganic nanomaterials, a series of biomass-derived nanomaterials, nanocellulose, are gradually coming to the attention of researchers and industries, exhibiting excellent mechanical properties while maintaining their renewable and degradability. − The nanocomposites reinforced with nanocelluloses face the same issue of dispersibility . Fortunately, the hydroxyl groups on the surface of nanocellulose can perform as reaction points for grafting reactions. , Several reports about applying surface-grafted cellulose nanocrystals (CNC), a type of nanocellulose with a rod-like structure, for the construction of one-component nanocomposites have been published. − Due to the diversity of nanocellulose sources, grafting methods, and grafted polymer types, it is improper to compare the results of these studies directly, and the reinforcing mechanism was unclear. Recently, Hansoge et al attempted to explore the relationship between the structure and properties of nanocellulose-reinforced one-component composites through computational approaches.…”