化学修饰石墨烯膜（CMG膜）作为由二维石墨烯纳米片层构筑而成的新型宏观组装体材料，拓展了纳米尺度石墨烯在宏观层面的实际应用。得益于优异的性能与独特的层状结构，该材料在诸多领域均展现出潜在的应用价值。其力学性能作为保障膜材料在特定领域稳定应用的关键性能，受到了广泛的关注与研究。虽然近十几年相关研究的发展已经取得了许多重要成果，但膜材料的力学性能与其构筑基元相比，仍存在巨大差异。掌握材料微观结构与性能的关系，是指导设计新材料的关键。本论文旨在通过对CMG膜材料微观结构与力学性能两者间重要关系的研究，丰富从微观结构角度对膜材料力学特征的理解，为设计制备力学性能优异的CMG膜材料提供新思路，主要结果如下： 揭示了膜材料微观褶皱结构与泊松比行为的关系。基于荧光数据图像散斑相关的测试方法，首次观测出CMG膜材料的负泊松比行为，并通过实验表征和理论模型证明该行为来源于膜内部的微观褶皱结构，且调控膜的褶皱结构可调节其负泊松比效应。该工作也为CMG膜材料的高韧性特征提供了另一角度的力学理解，即膜材料韧性的提高得益于负泊松比效应带来的力学增强。 提出了褶皱互锁微结构对膜材料的增强增韧机制。通过向低缺陷氧化石墨烯（GO0）分散液中引入具有一维纳米结构的纳米纤维素（CNC），诱导其发生凝胶化，利用凝胶浇筑技术成功制备片层具有多种褶皱拓扑结构的rGO0/CNC复合膜材料。该CMG膜材料表现出优异的力学、电学性能（强度：765 ± 43 MPa，韧性：15.64 ± 2.20 MJ m3，电导率：1105 ± 17 S cm1）。证明由CNC诱导GO0片层产生的褶皱互锁结构在材料抵抗外力时起到了积极作用，实现了膜材料的协同增强增韧。从微观结构设计的角度，为制备综合性能优异的CMG膜材料提供新策略。 利用片层面上无机质互锁凸起结构实现高模量CMG膜材料的制备。通过溶液加工方法，设计表面具有无机质互锁凸起结构的GO复合片层，利用材料复合技术和热压处理方法，制备得到模量高达76.1 ± 6.2 GPa的CMG膜材料。提出片层表面互锁的硬质凸起结构在材料受到外加载荷时可起到防止片层发生相互滑移的作用，从而提高了膜材料的抗形变能力。开发的具有机械互锁作用的界面微观结构设计方法，为制备高模量CMG膜材料提供了新的设计理念。

Chemically modified graphene (CMG) films are macrostructural assemblies of two dimensional graphene-derived nanosheets, which largely extend applications of the nanostructure graphene. Benefiting from their fascinating mechanical, electrical and thermal properties and unique inner layered microstructure, CMG films demonstrate potential applications in plentiful fields. The mechanical property of CMG films is one of essential performances which enables their long-time stability during application. Although decades of intensive works have achieved sufficient development on improving their mechanical properties, the best relevant performances of CMG films are still several orders of magnitude lower than those of the monolayer graphene. Grasping the relationship between properties and microstructures of materials is an important part of designing advanced materials. In this dissertation, we focus on the research of mechanics and microstructures of CMG films, aim to reveal the mechanism of mechanical enhancement from microstructure point and put forward new strategies for constructing CMG films with decent performances. The results of our works are summarized below. The relationship of microstructural wrinkle texture and Poisson’s ratio behavior of CMG films is revealed. Fluorescent digital image correlation was used to measured the in-plane deformation of CMG films during the loading process and results show that CMG films possess remarkable negative Poisson’s behaviors which have never been reported before. Experimental characterization and theoretical analysis jointly demonstrate this unique mechanical property of CMG films is originated from their microstructural wrinkle textures. In addition, Modulating these textures of the inter-connected network of close-packed laminates in CMG films yields finely-tuned negative Poisson’s ratios. This work promotes a supplementary understanding of high toughness of CMG films in microstructural point, that is the enhancement on toughness of films is profiting from their obvious auxetic behaviors, and thus presents a design for advanced materials with enhanced toughness. The strengthening and toughening mechanism of interlocked wrinkle microstructure in CMG composite films is proposed. Cellulose nanocrystal with one dimensional nanostructure was introduced to GO0 (GO sheets with almost intact structure) dispersion and triggered the gelation of GO0 dispersion. Followed by gel-film transforming process and reduction treatment, rGO0/CNC composite films delivering an ultrahigh tensile strength of 765 ± 43 MPa, a superior toughness of 15.64 ± 2.20 MJ m?3, as well as a high electrical conductivity of 1105 ± 17 S cm?1, were successfully prepared. CNC as an reinforcement element of composite film, interacts with flexible nanosheets and introduces nacre-like interlocked wrinkle textures in microstructure of materials, which is mainly responsible for synergistic enhancements of strength and toughness of composite films. The mechanism proposed here suggests a feasible strategy for the fabrication of CMG films with superior mechanical performances by topology design. The preparation of CMG films with high modulus was realized by rationally decorating inorganic nanoasperities structure on lamellas. The composite nanosheets in which GO nanosheets are sandwiched by inorganic layers with nanoasperities on their surface, were synthesized by solution processing method, and assembled into graphene-based macroscopic architectures by vacuum-assisted filtration. After hot-pressing procedure, as-prepared CMG films show high modulus up to 76.1 ± 6.2 GPa. The interlocked inorganic nanoasperities on the surface of nanosheets controlling the frictional resistance to the sliding of platelets while CMG film bearing applied load, significantly improve the deformation resistance of material. A novel design principle is raised here to improve modulus of CMG films by strengthening of relevant interfaces.