Preparation of monolithic silica HPLC columns with truss-structured skeletons and embedded surfactant-templated mesopores

Abstract Monolithic macro/mesoporous silica gels have been prepared via a sol-gel process using triblock copolymer Pluronic P123 (EO 20 PO 70 EO 20 ) as a structure-directing agent. In this synthesis, P123 not only induces phase separation to form macroporous structure but also acts as a supramolecular template to form mesopores with precisely controlled shape and size. Obtained was a monolithic silica composed of continuous truss-like columnar skeletons in which cylindrical mesopores are arranged in a 2D-hexagonal symmetry. These monolithic silica gels have extremely high porosity approaching 90% and exhibited high specific surface area and sharp pore size distribution as revealed by N 2 sorption measurements. Combinations of the initial composition and the post-gelation treatment on wet gels allowed the control of physical properties of meso- and macropore structures. The monolithic HPLC columns prepared using these silica gels surface-modified by ODS (octadecylsilyl) ligands gave as many as 140,000 theoretical plates/m for the separation of alkylbenzenes in a reversed-phase mode. Very weak dependence of height equivalent to theoretical plate, H, on the mobile phase velocity was also recognized in comparison with conventional particle-packed columns. Graphical Abstract