Self-assembled monolayers of alkylphosphonic acids on metal oxides
Self-assembled monolayers of alkylphosphonic acids on metal oxides
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DOI：
10.1021/la9607621
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发表时间：
1996-12-25
期刊：
影响因子：
3.9
通讯作者：
Reven, L
中科院分区：
文献类型：
--
作者：
Gao, W;Dickinson, L;Reven, L
通过将十八烷基膦酸（ODPA）吸附在无孔ZrO2、TiO2和锆化二氧化硅粉末上，可以制备致密、高度有序的单层膜。ODPA与Al2O3发生强烈反应，形成大块（烷基铝）膦酸盐。ODPA单层膜的红外光谱表明其构象有序程度可与平面基底上的自组装单层膜相媲美。从固态P-31和C-13核磁共振谱来看，表面相互作用的强度和构象有序程度依次递减为：锆化二氧化硅> ZrO2 > TiO2。虽然内亚甲基主要呈全反式构象，但链末端高度无序。在锆化二氧化硅的情况下，有证据表明形成了一些大块的烷基膦酸锆。2D WISE NMR实验的质子线宽测量显示，与大块晶体相相比，ZrO2和TiO2上的ODPA单层中存在相当大的链迁移率。
Dense, highly ordered monolayers can be prepared by the adsorption of octadecylphosphonic acid (ODPA) onto nonporous ZrO2, TiO2, and zirconated silica powders. ODPA reacts strongly with Al2O3 to form a bulk (aluminoalkyl)phosphonate. The infrared spectra of the ODPA monolayers indicate a degree of conformational order comparable to self-assembled monolayers on planar substrates. From the solid-state P-31 and C-13 NMR spectra, the strength of the surface interaction and the degree of conformational order decrease in the following order: zirconated silica > ZrO2 > TiO2. Although the inner methylenes are primarily in an all-trans conformation, the chain termina are highly disordered. In the case of zirconated silica, there is evidence for the formation of some bulk zirconium alkylphosphonate. Proton line width measurements from 2D WISE NMR experiments reveal that considerable chain mobility is present in the ODPA monolayers on ZrO2 and TiO2, in contrast to bulk crystalline phases.