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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Development of Structure in Hexadecyltrimethoxysilane Adsorbed on Silica
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Development of Structure in Hexadecyltrimethoxysilane Adsorbed on Silica

机译：在二氧化硅上吸附的十六烷基三甲氧基硅烷结构的研制

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The structural assemblies of hexadecyltrimethoxysilane (HDTMS) on silica particles were determined using temperature-modulated differential scanning calorimetry, thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), and powder X-ray spectroscopy. At very small adsorbed amounts (<0.6 mg/m(2)), HDTMS molecules decomposed at a slightly higher temperature than bulk, exhibited symmetric and asymmetric FTIR resonances similar to those of liquid alkanes, showed a broad powder X-ray peak, and had a very small enthalpy of melting. These observations are consistent with poorly organized, disordered alkyl chains of directly attached molecules. At larger adsorbed amounts (>0.6 mg/m(2) or more) in the "multilayer region", the chains adopted more trans(anti) conformations, their decomposition temperatures approached those of the bulk condensed HDTMS, and a sharper primary powder X-ray peak was observed. Also, both melting and crystallization enthalpies for the bound HDTMS were found to exponentially approach the bulk enthalpy. In particular, the enthalpy changes were fitted with a linear dependence for the "sub-monolayer" and then an exponential approach to bulk with an exponential constant of about 1.6 mg/m(2). Together, these changes provide insight into how adsorbed HDTMS molecules underwent structural changes, from directly bonded on the surface to bulklike material.
机译：使用温度调制的差分扫描量热法，热重分析，傅里叶变换红外光谱（FTIR）和粉末X射线光谱法测定二氧化硅颗粒上的六烷基三甲氧基硅烷（HDTMS）的结构组件。在非常小的吸附量（<0.6mg / m（2））中，在稍高的温度下分解的HDTMS分子比体积略高，表现出与液体烷烃类似的对称和不对称的FTIR共振，显示出宽的粉末X射线峰，和融化了非常小的焓。这些观察结果与直接附着的分子的良好组织，无序的烷基链一致。在“多层区域”中的较大吸附量（> 0.6mg / m（2）或更多）中，链条采用更多的反式（抗）构象，它们的分解温度接近散装浓缩的HDTMS的那些，以及更清晰的初级粉末x -Ray峰被观察到。而且，发现结合HDTMS的熔融和结晶焓被呈指数呈散装焓。特别地，焓变化适用于“亚单层”的线性依赖性，然后是指数稳定的指数方法，其指数常数为约1.6mg / m（2）。这些变化在一起，深入了解吸附的HDTMS分子如何接受结构变化，从表面上直接粘合到散装材料上。

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