大孔硅胶的制备及其在多糖衍生物手性固定相上的应用

为制备孔径为100 nm的大孔硅胶，考察了热液法和焙烧法对球形硅胶（粒径5 μm，孔径10 nm）的扩孔效果。采用热液法扩孔时，在水溶液中加入22 g/L氟化钠，可以有效增强扩孔效果，在高压釜内160℃加热48 h便可扩孔至100 nm，但孔径不均匀。采用焙烧法扩孔时，通过调节焙烧温度、时间以及复盐LiCl-NaCl的加入量可以方便地控制扩孔速度与效果；在每10 g硅胶中加入1.125 g LiCl·H₂O和0.75 g NaCl，于500℃焙烧3~5 h，可得到100 nm大孔硅胶；该方法简单、高效，扩孔后的硅胶孔径分布均匀，表面形态与商品化的Fuji-1000硅胶相似。将两种扩孔方式得到的硅胶经氨基修饰后，涂覆纤维素-三（3，5-二甲基苯基氨基甲酸酯）制得了相应的手性固定相。结果表明，采用焙烧法扩孔得到的硅胶制备的固定相明显具有较好的分离选择性及分离度。

Preparation of macroporous silica and its application on polysaccharide derivative based chiral stationary phase

In order to prepare 100-nm macroporous silica, spherical silica (5 μm in particle size, 10 nm in pore diameter) was treated by hydrothermal or baking methods. During hydrothermal treatment, 22 g/L NaF was added, which efficiently promoted the enlargement of pore diameters. By this method, the average pore diameter of silica reached 100 nm after heating for 48 h at 160℃ in an autoclave, but showed a poor size distribution. In the baking method, pore diameter enlargement was controlled by modifying the baking temperature, time, and the amount of double salt LiCl-NaCl added. The addition of 1.125 g LiCl·H₂O and 0.75 g NaCl per 10 g silica and baking at 500℃ for 3-5 h yielded silica with 100-nm pore diameters. This method was more efficient, easier, and better in the product pore diameter distribution than hydrothermal treatment. The obtained silica was very similar to commercial Fuji-1000 gel. The macroporous silicas obtained from the hydrothermal and baking treatments were both modified with aminopropyl silane and coated by cellulose tri(3,5-dimethylphenyl carbamate) to prepare chiral stationary phases (CSPs). The CSP based on the baking-treated silica exhibited much better selectivity and resolution for enantiomers.