Polyhedral Oligomeric Silsesquioxane（POSS） Modified SiO₂ Core-shell Chromatographic Stationary Phase: Preparation And Its Separation Performence

Polyhedral oligomeric silsesquioxane（POSS）is a kind of organic-inorganic hybrid material with stable three-dimensional structure,which has been approved to be with the merits of excellent thermal stability and mechanical strength,oxidation and wear resistance,as well as good pH tolerance.In this work,we focus on the research about the preparation of polyhedral oligomeric silsesquioxane methacryl-substituted（POSS-MA）modified SiO₂core-shell chromatographic stationary phase and its separation performance.The full text is divided into four chapters:In the first chapter,four parts are included.The first part gives a brief review of the high performance liquid chromatography stationary phase.The second part briefly describes the research progress and related applications of polyhedral oligomeric silsesquioxane.The third part briefly describes the excellent properties of ionic liquids and its related applications.In the last part,the conception of this paper is introduced.In the second chapter,a novel type of POSS-MA modified silica（POSS@SiO₂）core-shell microsphere was developed as stationary phase for HPLC separation by using POSS-MA as the monomer via thiol-ene click reaction.The composition,morphology and stability of the prepared POSS@SiO₂ stationary phase were characterized by Fourier transform infrared experiments,scanning electron microscopy,thermogravimetric analysis and elemental analysis,respectively.The results showed that the POSS@SiO₂ stationary phase has been successfully prepared with high thermal and chemical stability.In addition,the residual methacrylate groups on the surface of the POSS@SiO₂ core-shell microsphere can be further functionalized so as to facilitate the fabrication of versatile stationary phases with variousseparationmechanisms.Forexample,azwitterionicionicliquid1-vinyl-3-carboxymethylimidazolium bromide（VCI?Br）was further used to functionalize the POSS@SiO₂ core-shell materials and the new VCI-POSS@SiO₂ core-shell microspheres were further verified via FT-IR and thermogravimetric analysis.These results approved the successful fabrication of the VCI-POSS@SiO₂ core-shell microspheres with high thermal and chemical stability.In the third chapter,the prepared POSS@SiO₂ and VCI-POSS@SiO₂ stationary phases were further used for high performance liquid chromatography.The retention mechanisms of POSS@SiO₂ column was investigated by alkylbenzenes and the new POSS@SiO₂ column exhibited reversed phase liquid chromatography retention mechanism.Compared with the commercial C8 column,the POSS@SiO₂ column exhibited with high separation efficiency and different separation selectivity when it was used for separation of alkylbenzenes,basic anilines and polycyclic aromatic hydrocarbons.At the same time,the retention mechanism of VCI-POSS@SiO₂ stationary phase was also investigated by using alkylbenzenes and nucleoside and nucleobase compounds.Both RPLC and hydrophilic interaction liquid chromatography（HILIC）retention mechanisms can be observed from the VCI-POSS@SiO₂column.Thus,the successful separation of hydrophilic uracil,adenosine,uridine and inosine can be achieved.In the fourth chapter:the last chapter summarizes the paper and illustrates the study results and reality significance.In this paper,POSS@SiO₂ core-shell chromatography stationary phase was prepared with a typical reversed phase liquid chromatography retention mechanism,and can be successfully applied to the separation and detection of hormones6-BA and KT in bean sprout extract.In addition,the residual methacrylate groups on the surface of the POSS@SiO₂ core-shell microsphere can be further functionalized to prepare versatile stationary phases with various separation mechanisms.