Dependence of the molecular aggregation state of octadecylsiloxane monolayers on preparation methods.
Dependence of the molecular aggregation state of octadecylsiloxane monolayers on preparation methods.
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DOI：
10.1021/la048544s
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发表时间：
2005-02
期刊：
影响因子：
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通讯作者：
T. Koga;M. Morita;H. Ishida;Hirohiko Yakabe;S. Sasaki;O. Sakata;H. Otsuka;A. Takahara
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文献类型：
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作者：
T. Koga;M. Morita;H. Ishida;Hirohiko Yakabe;S. Sasaki;O. Sakata;H. Otsuka;A. Takahara
采用掠入射X射线衍射(GIXD)、傅立叶变换红外光谱(FT-IR)、接触角测量、场发射扫描电子显微镜(FE-SEM)和扫描力显微镜(SFM)研究了十八烷基三甲氧基硅烷(OTMS)和十八烷基三氯硅烷(OTS)硅片衬底表面十八烷基硅氧烷单层的分子聚集状态。采用化学气相吸附法制备了OTMS单分子膜，并以化学吸附法(OTS-S)和水铸法(OTSW)制备了OTS单分子膜作为参比样品。GIXD、FT-IR、侧向力显微镜(LFM)和FE-SEM观察表明，室温下CVA法制备的OTMS单分子膜中的烷基链处于无定形状态。线性调频测量表明，化学吸附法制备的OTS-S单层膜从六方晶相到非晶相的转变温度约为333K。然而，用CVA法制备的OTMS单分子膜没有观察到相变。原子力显微镜(AFM)观察和接触角测量表明，CVA法制备的OTMS单分子膜与OTS单分子膜相比表面均匀。这些结果表明，CVA法制备的硅单层中的有机硅烷化合物以无定形状态固定在硅片衬底表面，这与化学吸附和注水法制备的六方晶态有很大不同。
The molecular aggregation state of octadecylsiloxane monolayers on Si-wafer substrate surfaces prepared from octadecyltrimethoxysilane (OTMS) or octadecyltrichlorosilane (OTS) was investigated on the basis of grazing incidence X-ray diffraction (GIXD), Fourier transform infrared spectroscopy (FT-IR), contact angle measurement, field emission scanning electron microscopy (FE-SEM), and scanning force microscopy (SFM). The OTMS monolayer was prepared by using the chemical vapor adsorption (CVA) method, and the OTS monolayers, which were used as reference samples, were prepared either by chemisorption (OTS-S) or by the water-cast method (OTS-W). The GIXD, FT-IR, lateral force microscopic (LFM) measurements, and FE-SEM observation revealed that the alkyl chains in the OTMS monolayers prepared using the CVA method are in an amorphous state at room temperature. According to the LFM measurement, the transition temperature from the hexagonal crystalline phase to the amorphous phase was found to be ca. 333 K for the OTS-S monolayer prepared by the chemisorption method. However, the phase transition was not observed in the OTMS monolayer prepared by the CVA method. Also, the atomic force microscopic (AFM) observation and the contact angle measurement showed that the OTMS monolayer prepared by the CVA method has a uniform surface when compared to the OTS monolayers. These results indicated that organosilane compounds in the monolayer prepared by the CVA method were immobilized on the Si-wafer substrate surface in an amorphous state, which was quite different from the hexagonal crystalline state obtained by the chemisorption and water-cast methods.