Laboratoire de Physique des Solides, UMR 8502 CNRS, Université Paris-Sud, Université Paris-Saclay. Bat 510, 91405 Orsay Cedex, France.
Nanoscale. 2017 Nov 16;9(44):17371-17377. doi: 10.1039/c7nr05723g.
We designed a nanocomposite consisting of CdSe nanoplatelets dispersed in the form of short stacks in the polybutadiene domains of a polystyrene-polybutadiene-polystyrene (SBS) thermoplastic elastomer matrix. Under strain, the material displays reversible, macroscopic anisotropic properties, e.g. the fluorescence signal. We present here a structural study of the composite under stretching, by in situ high-resolution X-ray scattering using synchrotron radiation. Modelling the scattering signal allows us to monitor the evolution of both the matrix and the platelets under strain. In particular, we show that the strain "reshuffles" the platelet stacks, which tilt their long axis from parallel to the plane of the microstructure lamellae at rest to perpendicular to this plane at high strain, at the same time breaking into smaller pieces, more easily accommodated in the soft butadiene domains. This reshuffling is fully reversed after strain relaxation. Moreover, it can be prevented by adding free oleic acid, which reinforces the interactions between the platelets in the stacks.
我们设计了一种由 CdSe 纳米板组成的纳米复合材料，这些纳米板以短堆的形式分散在聚苯乙烯-聚丁二烯-聚苯乙烯（SBS）热塑性弹性体基质的聚丁二烯域中。在应变下，该材料表现出可逆的宏观各向异性性质，例如荧光信号。我们在这里通过使用同步辐射的原位高分辨率 X 射线散射对复合材料在拉伸下的结构进行了研究。对散射信号进行建模可使我们能够监测应变下基质和板的演变。特别是，我们表明应变“重新排列”了板层堆，使它们的长轴从静止时的微结构层片平面平行变为高应变时的垂直，同时分裂成更小的碎片，更易于容纳在柔软的丁二烯域中。在应变松弛后，这种重新排列完全反转。此外，通过添加游离油酸可以防止这种重新排列，油酸增强了堆叠中板之间的相互作用。
