关键词: 纳米纤维素, 导电活性材料, 复合材料, 功能与应用

Abstract: As a natural renewable resource material, cellulose and its derivatives play an important role in the national production. With the development of nano-technology, one-dimensional nano-scale nanocellulose has emerged by chemical, physical and enzymatic methods. As a matrix material, nanocellulose has a rapid development in the field of flexible, transparent terms of screens, sensors and storage devices because of its property of high strength, high surface area, and low thermal expansion coefficient and easily woven into a mesh structure. According to the different preparation methods (mechanical, oxidation and hydrolysis method), it can be got two types of nanocellulose with different physical morphology and chemical modification group, that is cellulose nanofibrils and cellulose nanocrystals. According to different storage mechanisms, the conducting electroactive materials include conductive polymer (polypyrrole, polyaniline, etc.), metal oxide (manganese dioxide, titanium dioxide, zinc oxide, etc.) and carbon materials (carbon nanotubes, graphene, etc.). Because of the morphology differences of nanomaterials, nanocellulose and the conducting electroactive materials can be formed of electroconductive composites with different micro-scale and structural characteristics. In the research field, the conducting polymer/nanocellulose electroconductive composites are mainly used for electrochromic devices, electrochemical sensors, drive, and supercapacitors, especially for the pseudo-capacitance supercapacitors with better capacitance. Electroconductive composites combined nanocellulose with carbon nanotubes and graphene can be used as a flexible electrode for flexible batteries, and flexible supercapacitors. Metal oxide nanoparticles have unique magnetic, optical and piezoelectric properties, thus the metal oxide nanoparticles/nanocellulose electroconductive composites can be used for photovoltaic materials and solar cells. As the carrier material or skeleton supporting material with excellent structural stability and mechanical properties, nanocellulose could combine with a variety of inorganic or organic conductive nanomaterial to produce special functional materials with a high conductivity, photoelectric conversion and the electrochemical oxidation-reduction characteristics. This is because nanocellulose is liable to form film and gel and has good characteristics of high water absorption, swelling and biocompatibility. From the progress of the preparation method, conductive polymer not only can be used to form a conductive film material by dispersing it into the solution of nanocellulose, but also to obtain the conductive polymer/nanocellulose electroconductive composites by in-situ polymerization methods. Carbon nanotubes, graphene sheet and a particulate metal oxide can be mainly formed to a stable dispersion or hydrogel by dispersing them into the solution of nanocellulose, and further to obtain a film or aerogel material with good conductivity by solvent evaporation, filtration and freeze-drying or supercritical drying. They can also form a transparent conductive film material by the layer-by-layer self-assembly technology. There are large development potential of nanocellulose in the flexible electronic storage devices. In the future, the complex way, uniformity of dispersion, microstructure control, interface compatibility and interaction mechanism between nanocellulose and conducting electroactive materials will be studied deeply and play the role of nanocellulose platform for conducting electroactive materials further. Hope this review could provide some research ideas for further function and application research of nanocellulose.

Key words: nanocellulose, conducting electroactive materials, composites, function and application