木质纳米纤维素与金属氧化物纳米晶的界面结构与复合机理

Nano-(lingo)cellulose is one of the nanoscale biopolymer materials. Nanocellulose is an ideal substrate for metal oxide nanocrystals due to its abundant surface functional groups. The novel metal oxide nanocrystal-nanocellulose composite materials have many unique new functions, such as mechanical, optical, electromagnetic properties et al. As a developing composite material, the metal oxide nanocrystal-nanocellulose becomes a hot spot for frontier research. However, the interface structure and the interaction mechanism between nano-(lingo)cellulose substrates and metal oxide nanocrystals are indefinite, which limit the development of the advanced composite materials. In this project, we plan to prepare composite materials by using hydrothermal, sol-gel, and wet chemical methods to in-situ growing metal oxide nanocrystals onto the surface of nano-(lingo)cellulose with different morphologies and surface functional groups, which is collected from moso bamboo (Phyllostachys pubescens Maxel Exh. De Lehaie). We will investigate the effects of the nanocellulose in the growth of metal oxide nanocrystals at every stage by using XAFS (X-ray Absorption Fine Structure) technology, thus to determine the interactions and the combination of the covalent/non-covalent bonding between the metal oxide nanocrystals and the nano-(lingo)cellulose substrates. Besides that, we need to determine the interface structure between metal oxide nanocrystals and nano-(lingo)cellulose by HRTEM (High Resolution Transmission Electron Microscope) and HAADF (High-Angle Annular Detector Dark Field) technologies. This work will illuminate the relationship of the interface structure and the composite materials porperties. This project can reveal new scientific basis for the functional research and high-value utilization of nano-(lingo)cellulose, also provide theoretical support for the development of nanocellulose-based functional composite materials.

木质纳米纤维素是纳米级的天然高分子材料，表面丰富的官能团使其成为金属氧化物纳米晶的理想载体，两者复合后的新材料具有独特力学、光学、电磁等新型功能，是前沿研究的热点。然而，纳米纤维素基质与金属氧化物纳米晶之间的界面结构和相互作用机理尚未明确，限制了新型复合材料的设计与合成。本课题基于毛竹中提取的具不同形貌与表面官能团的木质纳米纤维素，以水热法、溶胶凝胶法和湿化学法在其表面沉积生长金属氧化物纳米晶，制备成复合材料。采用X射线吸收精细结构(XAFS)等方法分析纳米纤维素在金属氧化物纳米晶生长各阶段中的作用，揭示金属氧化物纳米晶与纳米纤维素基质间相互作用和共价键/弱键结合规律；并通过高分辨透射电镜(HRTEM)和高角度环形暗场(HAADF)等技术获得复合材料界面的精细结构，阐明界面结构与复合材料性能的关系；本项目为木质纳米纤维素的高值利用提供科学依据，对设计开发功能化的新型复合材料具有重要意义。

木质纳米纤维素作为纳米级的天然高分子材料是复合材料的理想载体。为了揭示木质纳米纤维素基体与金属氧化物纳米晶或有机物之间的界面结构和相互作用机理，项目以毛竹、桉木浆、麦秸秆中提取的具不同形貌与表面官能团的木质纳米纤维素为基体，采用水热法、湿化学法、双重交联法、仿生界面构筑法，在其表面沉积生长金属氧化物纳米晶及有机分子，并将其应用于轻木、棉织物等生物质基体材料上。制备出疏水亲油、放射性碘高效吸附剂、光催化剂、氧还原电催化剂、析氢电催化剂、锂电池电极等系列功能复合材料。上述研究通过光电子能谱（XPS）、固体核磁（NMR）、高分辨透射电镜(HRTEM)和高角度环形暗场(HAADF)等技术，获得复合材料界面的精细结构，揭示了金属氧化物纳米晶与不同纳米纤维素基质间可形成共格晶面、螯合、氢键、化学键结合等相互作用，建立了双重交联法、仿生界面构筑法和化学沉积法等系列复合方法。从分子水平及晶格层面阐明了纳米纤维素基复合材料的界面结构与复合机理，为木质纳米纤维素及生物质基体的高值利用提供了科学依据及科学途径，将复合后的新材料应用拓展到环境处理与能源转化等新领域。