LIONS, NIMBE, CEA, CNRS, Université Paris-Saclay, CEA-Saclay , 91191 Gif-sur-Yvette , France.
Sorbonne Universités, UPMC Univ. Paris 06, CNRS, Collège de France, Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP) , 4 place Jussieu , 75005 Paris , France.
Langmuir. 2018 Nov 6;34(44):13225-13234. doi: 10.1021/acs.langmuir.8b01075. Epub 2018 Oct 23.
Hybrid imogolite aluminosilicate nanotubes with methylated internal surface can be obtained by introduction of the corresponding organosilane during their synthesis. However, similarly to pristine imogolite, a number of side products, including proto-imogolite (open-imoLS), allophanes, and aluminum hydroxides, are formed, which ultimately impact on the properties of the dispersions. In order to minimize the proportion of these side products, we have here systematically explored the impact of the initial Si/Al ratio on the content of hybrid imogolite dispersions before and after dialysis. By combining cryo-transmission electron microscopy, inductively coupled plasma mass spectrometry, infrared spectroscopy, and small-angle X-ray scattering, we evidenced that the Si/Al ratio has a large impact on the formation of aluminum hydroxides that can be minimized with a slight excess of Si precursor. However, a large excess of Si is detrimental to the reaction yield leading to an important proportion of proto-imogolite. We propose that the optimal Si/Al ratio of ca. 0.6 can both minimize the proportion of aluminum hydroxides and proto-imogolite. These results suggest that the dynamic and therefore reactive character of imogolite dispersions may have been so far underlooked.
通过在合成过程中引入相应的有机硅烷，可以得到具有甲基化内部表面的杂化埃洛石纳米管。然而，与原始埃洛石类似，会形成许多副产物，包括原埃洛石（开环埃洛石）、无定形层状硅铝酸盐和氢氧化铝，这些副产物最终会影响分散体的性质。为了尽量减少这些副产物的比例，我们在这里系统地研究了初始 Si/Al 比对于透析前后杂化埃洛石分散体含量的影响。通过结合低温透射电子显微镜、电感耦合等离子体质谱、红外光谱和小角 X 射线散射，我们证明 Si/Al 比对形成氢氧化铝有很大的影响，通过稍微过量的 Si 前体可以将其最小化。然而，过量的 Si 不利于反应产率，导致原埃洛石的比例很大。我们提出，最佳的 Si/Al 比约为 0.6，既可以最小化氢氧化铝和原埃洛石的比例。这些结果表明，埃洛石分散体的动态特性，因此也包括其反应性，迄今为止可能被忽视了。
