Saarland University, Inorganic Solid State Chemistry, Am Markt Zeile 3, D-66125 Saarbrücken, Germany.
J Colloid Interface Sci. 2012 May 15;374(1):77-82. doi: 10.1016/j.jcis.2012.01.015. Epub 2012 Jan 17.
The surface hydroxyl content and surface structure of silica and other oxides with and without surface modification were systematically studied by solid state (29)Si NMR, thermogravimetric analysis, and the lithium alanate method. Aerosil 90 as a well described reference system and functionalized zirconia-silica particles were used in the validation of the lithium alanate method. 3-Methacryloxypropyltrimethoxysilane and dodecylphosphonic acid were applied as surface modifiers. The determination of silanol content of Aerosil 90 by (29)Si NMR and TGA confirms the results obtained by the lithium alanate method, which also allows for the determination of the remaining surface hydroxyl content after surface modification. For both silane coupling agents, the residual hydroxyl content of modified zirconia-silica is decreased by a factor of approximately 2 compared with that of the unmodified mixed oxide, whereas after modification with dodecylphosphonic acid, the hydroxyl content is slightly higher. These results are again in good agreement with those by (29)Si NMR confirming that the lithium alanate method is a reliable and easily practicable method for surface hydroxyl determination.
通过固态（29）Si NMR、热重分析和锂铝酸盐法系统研究了具有和不具有表面改性的二氧化硅和其他氧化物的表面羟基含量和表面结构。Aerosil 90 作为一个经过良好描述的参考体系和官能化的氧化锆-硅粒子被用于锂铝酸盐法的验证。3-甲基丙烯酰氧基丙基三甲氧基硅烷和十二烷基磷酸被用作表面改性剂。（29）Si NMR 和 TGA 对 Aerosil 90 的硅醇含量的测定证实了锂铝酸盐法的结果，该方法还可以测定表面改性后剩余的表面羟基含量。对于两种硅烷偶联剂，与未改性的混合氧化物相比，改性氧化锆-硅的残留羟基含量降低了约 2 倍，而用十二烷基磷酸改性后，羟基含量略高。这些结果与（29）Si NMR 的结果再次一致，证实锂铝酸盐法是一种可靠且易于实施的表面羟基测定方法。
