Preparation And Application Of Three Novel Organic-Silica Hybrid Monolithic Columns

The capillary monolithic column is a new type of column prepared by in-situ polymerization.It has the advantages of simple preparation,fast mass transfer rate,homogeneous structure and good permeability.Monoliths can be divided into organic monolithic column and silica monolithic column according to the preparation of the materials.The organic monolithic columns have poor stability while the silica monolithic columns have less silane types and complicated surface.Although the application of monolithic columns is increasing,the stability of monolithic materials and the diversity of functional groups greatly limit the sustainable development of monolithic columns.In recent years,the combination of organic monolithic column and silica monolithic column with great stability and diversity is widely used in researches.So it is necessary to look for more effective and simple method to prepare hybrid monolithic columns.In this paper,three novel organic-silica hybrid monolithic columns were synthesized by photoinduced thiol-ene radical polymerization,thermal-induced click reaction and sol-gel reaction.1.One-pot synthesis of porous polymer monolith decorated with itaconic acid in a capillary is described.The TMTVS was used as the siloxane backbone monomer,with tetrakis(3-mercaptopropanol)pentaerythritol(PETMP)as the organic crosslinking agent,and the functional monomer is modified to the surface of the porous monolithic material.At the same time,the preparation process of the monolithic column was optimized and the whole column structure with uniform pore size distribution and good permeability was obtained.The chromatographic characterization showed that the monolith exhibited good hydrophilic separation performance under high ratio of organic phase.The column showed high separation efficiency for amides,phenols and other strong hydrophilic polar small moleculars.The column efficiency of this monolith could be as high as 112560 N/m.At the same time,it can detect four phenols in water samples in the environment and has a good practical application prospect.2.In this sector,the hybrid monolithic column was in-situ fabricated by using polyhedral oligomeric silsesquioxanes(POSS-MA)with cage structure.The prepared monolithic material had good acid and alkali corrosion resistance as well as stable physical and mechanical properties.At the same time,the influencing factors including amount of cross-linkers,composition of porogenic solvents and polymerization temperature on the formation of the monolithic column were investigated.Further Nano-liquid chromatographic characterization revealed that the monolithic column had a good chromatographic separation effect on polar small molecules such as nucleosides,phenols,amides and bases,indicating good hydrophilic performance in the high organic phase.The effects of the concentrations of the triethylamine on the separation of several polar small molecules were also investigated.3.A new kind of organic-inorganic hybrid silica monolithic column possessing N-isopropylacrylamide has been developed for capillary liquid chromatography.The(TMOS)and vinyl silane(TMVS)were used as the backbone monomer while N-isopropylacrylamide was treated as the functional monomer through conventional sol-gol reaction.Two silane precursors were polymerized to form a stable inorganic skeleton.Then the monomer and the thermal initiator were added to the polymer to modify the surface of the hybrid column with the specific functional group.The prepared monolithic column had a uniform pore structure and good mechanical stability.Further chromatographic characterization revealed that the reverse phase separation mechanism was shown under high water phase conditions.The reversed-phase monolithic column has a good separation effect on anilines,phenols,benzoic acids as well as benzenes.The hybrid monolith can separate a series of water pollutants like polycyclic aromatic hydrocarbons,chlorophenols and perfluorinated compounds at the same time.The monolith also has good separation effects on macromolecule protein.