Laboratoire de Chimie Physique et Microbiologie pour l'Environnement, Unité Mixte de Recherche UMR 7564, CNRS-Université H. Poincaré Nancy I, 405 Rue de Vandoeuvre, F-54600 Villers-les-Nancy, France.
Talanta. 2003 May 1;59(6):1173-88. doi: 10.1016/S0039-9140(03)00024-9.
Various samples of aminopropyl-functionalized silica (APS) have been prepared by grafting an organosilane precursor 3-aminopropyl-triethoxysilane (APTES) onto the surface of silica gel. The amine group content of the materials has been adjusted by varying the amount of APTES in the reaction medium (toluene). The grafted APS solids have been characterized with using several analytical techniques (N(2) adsorption, X-ray photoelectron spectroscopy, infrared spectrometry) to determine their physico-chemical properties. Their reactivity in aqueous solutions was studied by acid-base titration, via protonation of the amine groups, and by way of complexation of these groups by Hg(II) species. APS stability in aqueous medium was investigated at various pH and as a function of time, by the quantitative analysis of soluble Si- or amine-containing species that have been leached in solution upon degradation of APS. The chemical stability was found to increase when decreasing pH below the pK(a) value corresponding to the RNH(3)(+)/RNH(2) couple, but very low pH values were necessary to get long-term stability because of the high local concentration of the amine groups in the APS materials. Adsorption of mercury(II) ions on APS was also performed to confirm the long-term stability of the grafted solid in acidic medium. Relationship between solution pH and APS stability was discussed. For sake of comparison, the stability of APS in ethanol and that of mercaptopropyl-grafted silica (MPS) in water have been briefly considered and discussed with respect to practical applications of silica-based organic-inorganic hybrids, e.g., in separation science or in the field of electrochemical sensors.
已通过将有机硅烷前体 3-氨丙基三乙氧基硅烷 (APTES) 接枝到硅胶表面来制备各种氨基丙基官能化的硅胶 (APS) 样品。通过改变反应介质（甲苯）中 APTES 的量来调整材料的胺基含量。已使用几种分析技术（N2 吸附、X 射线光电子能谱、红外光谱）对接枝 APS 固体进行了表征，以确定其物理化学性质。通过酸碱滴定法、通过胺基的质子化以及通过 Hg(II) 物种与这些基团的络合来研究它们在水溶液中的反应性。通过在 APS 降解时在溶液中浸出的可溶性 Si 或含胺的物质的定量分析，研究了 APS 在不同 pH 值和时间下在水介质中的稳定性。当将 pH 值降低到对应于 RNH3+ / RNH2 偶对的 pKa 值以下时，发现化学稳定性增加，但由于 APS 材料中胺基的局部浓度非常高，因此需要非常低的 pH 值才能获得长期稳定性。还进行了汞(II)离子在 APS 上的吸附，以确认接枝固体在酸性介质中的长期稳定性。讨论了溶液 pH 值与 APS 稳定性之间的关系。为了进行比较，简要考虑并讨论了 APS 在乙醇中的稳定性以及巯丙基接枝硅胶 (MPS) 在水中的稳定性，这与基于硅胶的有机-无机杂化材料的实际应用有关，例如分离科学或电化学传感器领域。
