Huang Jiankun, Zeng Jingbin, Wang Hongbin, Etim Ubong J, Liang Baoqiang, Meteku Edem B, Li Honglin, Wang Yiyan, Qiu Zhiwei, Rood Mark J, Yan Zifeng
College of Science, China University of Petroleum (east), Qingdao, 266580, China.
Nanoscale. 2020 Apr 28;12(16):8982-8990. doi: 10.1039/c9nr10593j. Epub 2020 Apr 9.
Light-weight metallic aero-sponges are highly desirable for electronics, energy storage, catalysis and environmental remediation. Although several fabrication methods have been developed, the mechanical strength and the structural fatigue resistance of the metallic aero-sponges remain unsatisfactory. Loofah sponge is known for its mechanical strength and grease absorption due to its highly ordered hierarchical laminae-trestle-laminae (L-T-L) microstructure. Inspired by this structure-function relationship, we engineered a highly ordered L-T-L structured copper aero-sponge by unidirectional freeze-casting of copper nanowires (CuNWs) and polyvinyl alcohols (PVA). By this approach, water-to-ice crystallization shaped the building blocks into vertically distributed microchannels and horizontally arranged hollow pores. The copper aero-sponge exhibits anisotropic mechanical elasticity with a maximum tolerable compressive stress of 57 kPa, sustainable resilience at a strain of 75% and structure-induced hydrophobicity with a water contact angle more than 130°. The elasticity and hydrophobicity of the copper aero-sponge are also superior to those of the mimicked loofah sponge and copper aero-sponge with disordered pore structure made by the conventional freeze-casting. This work can be extended to manufacture novel bioinspired aero-sponges/aero-gels with hierarchical ordered microstructures.
轻质金属气凝胶在电子、储能、催化和环境修复等领域具有很高的应用价值。尽管已经开发了几种制造方法，但金属气凝胶的机械强度和结构抗疲劳性仍不尽人意。丝瓜海绵因其高度有序的分层叶片 - 支架 - 叶片（L-T-L）微观结构而以其机械强度和吸油性而闻名。受这种结构 - 功能关系的启发，我们通过对铜纳米线（CuNWs）和聚乙烯醇（PVA）进行单向冷冻铸造，设计了一种高度有序的L-T-L结构铜气凝胶。通过这种方法，水 - 冰结晶将构建块塑造成垂直分布的微通道和水平排列的中空孔隙。铜气凝胶表现出各向异性的机械弹性，最大可承受压缩应力为57 kPa，在75%的应变下具有可持续的弹性，并且具有结构诱导的疏水性，水接触角大于130°。铜气凝胶的弹性和疏水性也优于通过传统冷冻铸造制成的具有无序孔结构的模拟丝瓜海绵和铜气凝胶。这项工作可以扩展到制造具有分层有序微结构的新型仿生气凝胶/气凝胶。
