Organosilane self-assembled monolayers formed at the vapour/solid interface
Organosilane self-assembled monolayers formed at the vapour/solid interface
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DOI：
10.1002/sia.1358
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发表时间：
2002-08-01
影响因子：
1.7
通讯作者：
Takai, O
中科院分区：
文献类型：
--
作者：
Sugimura, H;Hozumi, A;Takai, O
研究了常压条件下有机硅烷分子在气/固界面上的自组装，以便在氧化层覆盖的硅衬底上形成单分子膜。使用了三种类型的前体：正十八烷基三甲氧基硅烷(ods：H3C(CH2)(17)Si(OCH3)(3))、n-(6-氨己基)氨丙基三甲氧基硅烷(AHAPS：H2N(CH2)(6)NH(CH2)(3)Si(OCH3)(3))和氟烷基硅烷(Fas：heptadecafluoro-1，1，2，2-tetrahydro-decyl-l-trimethoxysilane，用椭偏仪和X射线光电子能谱研究了在100-150℃温度下形成的自组装单分子膜(SAM)的F3C(CF2)(7)(CH2)(2)Si(OCH3)(3))Characteristics。通过水接触角和Zeta电位测量进一步表征了单分子膜的化学性质。由ODS和FAS形成的自组装膜具有疏水性，与水的接触角为100度，而由AHAPS形成的自组装膜的水接触角接近60度。测量了每种自组装膜覆盖的SiO_2衬底的Zeta电位和等电点(IEP)，并与裸SiO_2衬底进行了比较。根据对SiO_2颗粒的实验结果，覆盖了ODS-SAM或Fas-SAM的SiO_2基板的等电点为pH 3.5-4.0，与聚乙烯和聚四氟乙烯平板的IPEP基本相同，而未涂覆的SiO_2基板的等电点则接近于2.0。在AHAPS-SAM的情况下，由于表面氨基的质子化，其表面在酸性条件下带正电荷。因此，AHAPS-SAM覆盖的底物的等电点为pH 7.5-8.0。版权所有(C)2002 John Wiley Sons，Ltd.
Self-assembly of organosilane molecules at the vapour/solid interface under atmospheric pressure conditions was explored in order to form a monolayer on oxide-covered silicon substrates. Three types of precursors were employed: n-octadecyltrimethoxysilane (ODS: H3C(CH2)(17)Si(OCH3)(3)), n-(6-aminohexyl)aminopropyltrimethoxysilane (AHAPS: H2N(CH2)(6)NH(CH2)(3)Si(OCH3)(3)) and fluoroalkyl-silane (FAS: heptadecafluoro-1,1,2,2-tetrahydro-decyl-l-trimethoxysilane, F3C(CF2)(7)(CH2)(2)Si(OCH3)(3))Characteristics of these self-assembled monolayers (SAMs) formed at a temperature of 100-150degreesC were studied based on ellipsometry and x-ray photoelectron spectroscopy. Chemical properties of the monolayers were characterized further by water contact angle and zeta-potential measurements. The SAMs formed from ODS and FAS were hydrophobic so as to show water contact angles of >100degrees, whereas that of the SAM formed from AHAPS was similar to60degrees. zeta-potentials and isoelectric points (IEPs) Of SiO2 substrates covered with each of the SAMs were measured and compared with a naked SiO2 substrate. The IEPs of the SiO2 substrate covered with the ODS- or FAS-SAM was pH 3.5-4.0, which was almost the same as those of polyethylene and polytetrafluoroethylene plates, whereas that of the naked SiO2 substrate was pH similar to2.0, as predicted from results on silica particles. In the case of the AHAPS-SAM, its surface was positively charged under acidic conditions due to protonation of surface amino groups. Consequently, the AHAPS-SAM-covered substrate showed an IEP of pH 7.5-8.0. Copyright (C) 2002 John Wiley Sons, Ltd.