Strong Inorganic Acid Initiated Polymerization Strategy For Room Temperature Preparation Of Monolithic Capillary Columns: Methodology And Applications

Monolithic materials with a porous "single particle" structure have been extensively evolved as separation media because of their large surface area, excellent permeability, fast mass transfer and enhanced efficiency. Compared with conventional packed columns, the monolithic capillary columns overcome the difficulties in the fabrication of retaining frits and the packing of small diameter particles into narrow-bore tubes, giving improved separation performance. Previous preparation of organic polymer-based monoliths usually requires additional conditions, such as elevated temperature, UV radiation,γ-irradiation, or even electro-beam irradiation. Furthermore, some polymerizations have to be performed with the use of catalyst that is toxic and difficult to remove. The purpose of this dissertation was to explore a novel methodology based on a room temperature strong inorganic acid initiated polymerization without the need for heating, UV-radiation, y-irradiation, or even electro-beam irradiation. New applications of the strategy to the preparation of different types of monolithic columns were also demonstrated. The main contents are summarized as follows:(1) Strong inorganic acid initiated polymerization was explored as a novel method for facile, room temperature, robust and rapid fabrication of monolith for capillary electrochromatography. Compared with conventional polymerizations, the present strong inorganic acid initiated polymerization avoided the involvement of heating, UV- andγ-irradiation, and strong inorganic acid was easier to be available than the initiator used in UV and thermally initiated polymerizations, offering the possibility for the facile fabrication of methacrylate-based monoliths at room temperature. It also had wide tolerance to the amount and variety of initiator, and reaction time. As separation media for capillary electrochromatography, the prepared monolithic columns not only provided good separation and reproducibility for neutral compounds with the number of theoretical plates even higher than 230000 plates m-1 for thiourea, but also were applicable for the separation of different types of analytes including nitrophenol isomers, non-steroidal anti-inflammatory drugs, and anilines. Column-to-column and batch-to-batch reproducibility for the prepared monoliths was acceptable and similar to the results obtained by thermal- and photo-initiation.(2) Graphene oxide sheets were first incorporated into an organic polymer monolith based on the room temperature strong inorganic acid initiated polymerization to form a novel monolithic stationary phase for capillary electrochromatography. Compared with the column without graphene oxide sheets, graphene oxide sheets incorporated polymer-based monolithic column where graphene oxide facilitated the separation of the selected neutral analytes, and led to different chromatographic retention. Furthermore, the proposed monolith also provided good reproducibility.(3) The room temperature polymerization protocol was explored for the inorganic monomer of y-methacryloxypropyltrimethoxysilane. A room temperature simultaneous hydrolysis and polymerization process was established as a novel method for the incorporation of y-methacryloxypropyltrimethoxysilane into the monolithic column for capillary electrochromatography. Hydrochloric acid was used to catalyst the hydrolysis reaction and to initiate the polymerization of the monomer. The proposed approach avoided the pretreatment of the capillary and the reaction was achieved at room temperature, providing great convenience for the operation. The prepared monolith exhibited distinct continuous porous structure and gave good performance for the separation of alkyl benzenes.