Preparation of Novel Hybrid Monoliths and Their Application in Separation and Enrichment

Author:Ma Shu Juan

Supervisor:wei yin mao


Degree Year:2019





With an increasing requirement for higher selectivity,sensitivity and throughput,the development of novel chromatographic separation materials has been a hot topic in the field of chromatography.Monoliths were paid more attention as novel chromatographic materials in recent two decades.Inorganic silica-based monoliths had a bicontinuous skeleton structure providing a rigid inorganic skeleton.But they generally showed lower stability under basic condition.Organic monoliths had relatively low surface area,leading to lower efficiencies of small molecules.Particularly,the swelling behavior in several organic solvents would be detrimental to their pore structure although they have good biological compatibility,wide application range of pH value.To balance these limitations,organic-inorganic hybrid monolithic materials emerged,which somewhat inherited the merits of both silica materials and organic materials including low shrinkage,satisfactory mechanical stability,controlling porous structure easily and so on.However,at present,there are many problems in preparation of hybrid monoliths,such as the complex process of synthetic route and limited production type.To address these problems,this dissertation is focused on developing novel methods to prepare hybrid monolithic materials.1.Epoxy-functionalized hierarchically porous hybrid monoliths(HPHMs)with micro/meso/macro-pores structures were prepared in a simple way.Firstly,a bulk monolithic material was formed via free radical polymerization between polyhedral oligomeric vinylsilsesquioxanes(vinylPOSS)and allyl glycidyl ether(AGE)in the presence of polycaprolactone(PCL).Then PCL was degraded with hydrochloric acid solution,and the epoxy-functionalized HPHM with specific surface area(636.7 m~2/g)were obtained.The as-synthesized materials were further modified with penicillamine to be used as hydrophilic interaction chromatography(HILIC)adsorbents for enriching N-glycopeptides in IgG and serum protein tryptic digests.Up to 23 N-glycopeptides were identified from IgG digest,and 385 N-glycopeptides and 283 N-glycosylation sites were identified from human serum digest,indicating better ability of enrichment for glycopeptides.2.A vinyl-functionalized hybrid monolith was fabricated via sol-gel reaction by using tetraethyl orthosilicate(TEOS)and vinyltriethoxysilane(VTES)as precursors.The resulting materials were further modified with glutathione(GSH)to improve their hydrophilicity via thiol-ene click reaction,and then could be used as HILIC adsorbents for enriching N-glycopeptides in IgG and mouse liver protein tryptic digests.Up to 20N-glycopeptides were identified from IgG digest,and 1638 N-glycopeptides and 674N-glycosylation sites were identified from human serum digest.3.A time-saving approach was first adopted to in situ fabricate hybrid monoliths within the confines of UV-transparent fused-silica capillary via photo-initiated thiol-yne polymerizationwithin10min.Asilicon-containingdiyne(1,3-diethynyltetramethyl-disiloxane,DYDS)was firstly copolymerized with three kinds of multithiols,respectively.These monoliths possessed bicontinuous porous structure,which was remarkably different from that via typical free-radical polymerization.The high separation efficiency for small molecules and biological macromolecule BSA digest was obtained in reversed-phase liquid chromatography(RPLC).4.The preparation of chiral columns is tedious and time-consuming.Here,a fast and robust approach was explored to fabricate cinchona-based monolithic hybrid chiral stationary phases(CSPs)via photo-initiated thiol-ene polymerization within 10 min in one step.A self-synthesizedoctakis(3-mercaptopropyl)octasilsesquioxane(POSS-SH)was polymerizedwithphenylisocyanatecinchonidine(PCD)and(+)-N,N’-diallyl-L-tartardiamide(DATDA)or 1,2,4-trivinylcyclohexane(TVCH).It was found that they exhibited different enantioseparation ability due to using different multivinyl crosslinkers.