Wu H, Chen L X, Zeng X Q, Ren T H, Briscoe Wuge H
School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, PR China.
Soft Matter. 2014 Aug 7;10(29):5243-8. doi: 10.1039/c4sm00887a. Epub 2014 Jun 19.
Upon evaporation, ZnO nanorods in a nanofluid droplet undergo rapid and spontaneous chemical and morphological transformation into centimetre-long Zn(OH)2 fibres, via a mechanism very different from that for coffee rings. We show that the detailed nanostructure and micromorphology in the residual thin film depend intricately on the ambient moisture, nanofluid solvent composition and substrate surface chemistry. Upon thermal annealing, these Zn(OH)2 fibres readily undergo further chemical and morphological transformation, forming nanoporous fibres with the pore size tuneable by temperature. Our results point to a simple route for generating a self-assembled 3D structure with ultralong and nanoporous ZnO/Zn(OH)2 fibres/belts, and may also be of interest to the fields of evaporation controlled dynamic self-assembly, non-equilibrium crystallisation, and flow and fingering instabilities in nanofluids.
蒸发时，纳米流体液滴中的氧化锌纳米棒会通过一种与咖啡环形成机制截然不同的过程，迅速且自发地发生化学和形态转变，形成厘米长的氢氧化锌纤维。我们表明，残余薄膜中的详细纳米结构和微观形态与环境湿度、纳米流体溶剂组成以及基底表面化学密切相关。热退火后，这些氢氧化锌纤维很容易进一步发生化学和形态转变，形成孔径可通过温度调节的纳米多孔纤维。我们的结果指出了一条生成具有超长且纳米多孔的氧化锌/氢氧化锌纤维/带的自组装三维结构的简单途径，并且可能在蒸发控制的动态自组装、非平衡结晶以及纳米流体中的流动和指进不稳定性等领域也具有重要意义。
