Eeltink Sebastiaan, Herrero-Martinez José Manuel, Rozing Gerard P, Schoenmakers Peter J, Kok Wim Th
Polymer-Analysis Group, Van't Hoff Institute for Molecular Sciences, University of Amsterdam, The Netherlands.
Anal Chem. 2005 Nov 15;77(22):7342-7. doi: 10.1021/ac051093b.
Methacrylate ester-based monolithic stationary phases were prepared in situ in fused-silica capillaries and simultaneously in vials. The influence of the composition of the polymerization mixture on the morphology was studied with mercury intrusion porosimetry, scanning electron microscopy, and nitrogen adsorption measurements. A high-density porous polymeric material with a unimodal pore-size distribution was prepared with 40 wt % monomers and 60 wt % solvent in the mixture. A low-density material, prepared with a 20:80 ratio of monomers versus pore-forming solvent, showed a bimodal pore-size distribution and a much finer structure than the high-density monolith. The characteristic pore size could be controlled by changing the ratio of pore-forming solvents. With increasing solvent polarity, both the pore size and the dimension of the globules increased. The best efficiency in the CEC mode was obtained with an average pore size of 600 nm. Low-density monoliths exhibited lower A- and C-terms than high-density monoliths. With the optimal monolithic material, a minimum plate height of 5 mum could be obtained. The low-density monolith also performed better in the HPLC mode, giving a minimum plate height of 15 mum and a much higher flow permeability than that of the high-density material.
甲基丙烯酸酯基整体固定相在熔融石英毛细管中以及同时在小瓶中进行原位制备。采用压汞法、扫描电子显微镜和氮吸附测量研究了聚合混合物组成对形态的影响。在混合物中使用40 wt%的单体和60 wt%的溶剂制备了具有单峰孔径分布的高密度多孔聚合物材料。以单体与致孔溶剂20:80的比例制备的低密度材料显示出双峰孔径分布，并且结构比高密度整体材料精细得多。特征孔径可通过改变致孔溶剂的比例来控制。随着溶剂极性的增加，孔径和小球尺寸均增大。在CEC模式下，平均孔径为600 nm时效率最佳。低密度整体材料的A项和C项比高密度整体材料低。使用最佳的整体材料，可获得最小板高为5 µm。低密度整体材料在HPLC模式下也表现更好，最小板高为15 µm，且流动渗透率比高密度材料高得多。
