Ye Shibing, Chen Bin, Feng Jiachun
State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, Fudan University, Shanghai 200433, China.
Sci Rep. 2015 Aug 27;5:13102. doi: 10.1038/srep13102.
Combined high strength and toughness of film materials are rather important for their industrial applications. As a new class of films, graphene oxide films (GOFs) attract intense attention in many applications but are frequently divergent, inconsistent, and poorly reproducible in their mechanical properties. In this study, we first demonstrate that different chemical compositions and assembly structures probably are responsible for the difference in elongations between cast GOFs and filtration GOFs. Comprehensive analysis of the morphologies and mechanical properties indicates that the enhanced elongation of the thick cast GOFs is mainly attributed to the presence of a unique skin-wrinkles-skin structure, which more easily forms in cast GOFs than in filtration counterparts. On the basis of this finding, we attempt to optimize the strength-toughness performance of the cast GOFs by adjusting their structures. With an appropriate thickness of 12.5 μm, the GOFs can achieve an ultrahigh toughness up to 4.37 MJ m(-3), which is even comparable to the polymer-toughening graphene/GO-based paper-like materials. Such an optimization of the mechanical properties from the perspective of skin-wrinkles-skin structure appears to be a universal approach that could be extended to a variety of other film materials.
薄膜材料兼具高强度和高韧性对于其工业应用而言相当重要。作为一类新型薄膜，氧化石墨烯薄膜（GOFs）在许多应用中备受关注，但其机械性能往往存在差异、不一致且难以重现。在本研究中，我们首先证明不同的化学组成和组装结构可能是导致浇铸法制备的GOFs与过滤法制备的GOFs伸长率不同的原因。对形态和机械性能的综合分析表明，较厚的浇铸法制备的GOFs伸长率提高主要归因于其独特的“表皮-褶皱-表皮”结构的存在，这种结构在浇铸法制备的GOFs中比在过滤法制备的GOFs中更容易形成。基于这一发现，我们试图通过调整浇铸法制备的GOFs的结构来优化其强度-韧性性能。当厚度为12.5μm时，GOFs可实现高达4.37 MJ m⁻³的超高韧性，这甚至可与聚合物增韧石墨烯/氧化石墨烯基纸状材料相媲美。从“表皮-褶皱-表皮”结构的角度对机械性能进行这样的优化似乎是一种通用方法，可扩展到各种其他薄膜材料。
