Study On Preparation Andcharacterization Of Periodic Mesoporous Organosilicas

Research on chromatographic stationary phase has always been the focus in chromatography sphere. Periodic mesoporous organosilicas (PMOs) is characteristic of high specific surface area, ordered arrangement of the pore structure and uniform and adjustable pore size. Thus, it will show shows good prospects in chromatography sphere. Phenylene-bridged,ethane-bridged and biphenylene-bridged PMOs materials were prepared in this paper, respectively. Then three types of PMOs were characterized by a variety of physical and chemical methods. And chromatographic performance and retention mechanism were also studies.1. The spherical phenylene-bridged,ethane-bridged and biphenylene-bridged PMOs were synthesized with triblock copolymers and ionic surfactant as template under the acid medium (phenylene-PMOs, ethane-PMOs,biphenylene-PMOs). These materials were packed and their chromatographic performance was evaluated. The results showed three kinds of stationary phases have reversed phase chromatographic performance.Phenylene-PMOs has good stereoselective and remarkably planarity recognition ability which performed clear advantage in separation of position isomer.2. The porosities and pore size distributions of phenylene-PMOs and ethane-PMOs were determinated by size-exclusion chromatography. The result was consistent with that of nitrogen adsorption-desorption test. This method reflected a more realistic pore size distribution of packings in the water-phase system.3. The thermodynamic property of spherical phenylene-PMOs and biphenylene-PMOs as HPLC stationary phase was investigated and compared with commercial grafted C18 and phenyl stationary phases for polycyclic aromatic hydrocarbons(PAHs). The result showed that enthalpy-entropy compensation effect does not exist for homemade PMOs. The retention mechanism of solutes on the prepared stationary phases involves synergistic interaction of hydrophobic,π-πand inclusion interactions, which is different with that on the commerical stationary phases.