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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Thermally Changing Lattice Distance of Lamella in the Hydrated Solid of Octadecyltrimethylammonium Chloride
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Thermally Changing Lattice Distance of Lamella in the Hydrated Solid of Octadecyltrimethylammonium Chloride

机译：十八烷基三甲基氯化铵水合固体中薄片的晶格距离热变化

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A temperature scanning small-angle X-ray scattering measurement was carried out for the hydrated solids of octadecyltrimethylammonium chloride (OTAC). A gradual change of the lattice spacing of lamella-like structure from 40 nm at 5 °C to 20 nm at 18 °C was observed in the melting process of the hydrated solid that was incubated at 4 °C for a period of 24 h in the aqueous solution, while little change of the lattice spacing of about 20 nm was observed in the same process of the hydrated solid that was incubated at 4 °C for a period about 10 min. This indicates structural changes of the hydrated solid during the incubation at 4 °C and in the melting process. Corresponding to the nanostructure changes, broad endothermic peaks were observed at temperatures from 13 to 22 °C for the former hydrated solid and at temperatures from 15 to 21 °C for the latter hydrated solid in difference scanning calorimetry measurements. The structure change at temperatures below 13 °C is considered to be athermal from the fact that no endothermic peak is observed there. Large dielectric dispersions at frequencies at about 10 kHz were observed for the suspensions of hydrated solids but not for the solutions of dissolved solids. It was found that the electric conductance of the hydrated solid suspensions was much lower than that of the solutions of dissolved solids. The observed electric properties indicate that an amount of the free chloride ion is very small and that the chloride ions binding to the ammonium groups are movable in the hydrated solids by responding to an applied electric field. The electric conductance of suspension of the hydrated solid being incubated at 4 °C for 10 min was 4 times as large as that of a suspension of the hydrated solid being incubated at the same temperature for 24 h. This indicates that the structural change of the OTAC hydrated solid at 4 °C is related to the chloride ion binding to the hydrated solid. The experimental results described above suggest that the lamella in the hydrated solid of OTAC is undulated and that the wavelength of undulation increases with the incubation at a temperature much lower than the melting temperature.
机译：对十八烷基三甲基氯化铵（OTAC）的水合固体进行温度扫描小角X射线散射测量。在4°C下孵育24 h的水合固体熔融过程中，观察到片状结构的晶格间距从5°C的40 nm逐渐变至18°C的20 nm。在水溶液中，在与水化固体在4°C下孵育约10分钟的相同过程中，观察到约20 nm的晶格间距几乎没有变化。这表明水合固体在4°C保温过程中和融化过程中的结构变化。对应于纳米结构的变化，在差示扫描量热法测量中，对于前一种水合固体，在13至22℃的温度下观察到宽的吸热峰，对于后一种水合固体，在15至21℃的温度下观察到宽的吸热峰。由于在该温度下未观察到吸热峰，因此在低于13°C的温度下，结构变化被认为是无热的。对于水合固体的悬浮液，在约10 kHz的频率处观察到较大的介电色散，但对于溶解的固体溶液则未观察到。发现水合固体悬浮液的电导率远低于溶解固体溶液的电导率。观察到的电性能表明，游离氯离子的量非常小，并且与铵基结合的氯离子可通过响应施加的电场在水合固体中移动。在4°C下孵育10分钟的水合固体悬浮液的电导率是在相同温度下孵育24小时的水合固体悬浮液的电导率的4倍。这表明OTAC水合固体在4°C下的结构变化与氯离子与水合固体的结合有关。上述实验结果表明，OTAC的水合固体中的薄片是起伏的，并且起伏的波长随着在比熔融温度低得多的温度下孵育而增加。

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