Unusual Interfacial Freezing Phenomena in Hexacontane/Silica Composites
Unusual Interfacial Freezing Phenomena in Hexacontane/Silica Composites
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六烷/二氧化硅复合材料中异常的界面冻结现象
DOI：
10.1021/acs.jpcb.7b00603
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发表时间：
2017
影响因子：
3.3
通讯作者：
Wang Dujin
中科院分区：
文献类型：
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作者：
Gao Xia;Su Yunlan;Zhao Weiwei;Qian Qingyun;Chen Xin;Wittenbrink Robert;Wang Dujin
采用差示扫描量热法（DSC）、固体13 C核磁共振（13 C NMR）和质子NMR弛豫实验研究了不同组成的正十六烷（C60 H122）/二氧化硅（SiO2）复合材料的结晶行为。通过DSC分析，发现C60 H122/SiO2复合材料中的C60 H122分子参与了自由体相C60 H122中不存在的界面冻结过程。用掠入射X射线衍射法对吸附在硅表面的SiO2薄膜进行了表征，证实了C60 H122分子的取向为垂直于硅表面.固体~（13）C NMR数据表明，界面单层膜为正交相，存在一定的链无序。据推测，在二氧化硅颗粒的存在下形成的C60 H122的“界面冻结”是由分子之间的强吸引力和二氧化硅表面上的界面分子数量增加的组合驱动的。
The crystallization behaviors ofn-hexacontane (C60H122)/Stöber silica (SiO2) composites with various compositions were investigated by a combination of differential scanning calorimetry (DSC), solid-state13C nuclear magnetic resonance (solid-state13C NMR), and proton NMR relaxation experiments. By means of DSC, C60H122molecules in C60H122/silica composites were observed to be involved in the interfacial freezing not present in the free bulk C60H122. The orientation of C60H122molecules, being preferentially normal to silica surface, was confirmed by grazing incidence X-ray diffraction experiments on thinn-hexacontane film adsorbed on the silicon wafer with a native SiO2layer. Inferred from the solid13C NMR data, the interfacial monolayer is in orthorhombic phase with certain chain disorders. It is speculated that the “interfacial freezing” of C60H122formed in the presence of silica particles is driven by the combination of the strong attraction between the molecules and the enhanced number of interfacial molecules on the silica surface.