| 1. |
- Chen, Xiao-Jia, et al.
(author)
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Effect of ion adsorption on CEC separation of small molecules using hypercrosslinked porous polymer monolithic capillary columns
- 2012
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In: Journal of Separation Science. - : Wiley-VCH Verlagsgesellschaft. - 1615-9306 .- 1615-9314. ; 35:12, s. 1502-1505
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Journal article (peer-reviewed)abstract
- Both poly(styrene-co-vinylbenzyl chloride-co-divinylbenzene) and poly(4-methylstyrene-co-vinylbenzyl chloride-co-divinylbenzene) monolithic columns have been hypercrosslinked and for the first time used to achieve capillary electrochromatographic separations. Although these columns do not contain ionizable functionalities, electroosmotic flow was observed due to adsorption of ions from a buffer solution contained in the mobile phase on the surface of the hydrophobic polymer. An increase of more than one order of magnitude was observed with the use of both monolithic polymers. The hypercrosslinking reaction creates a large surface area thus enabling adsorption of a much larger number of ions. Alkylbenzenes were successfully separated using the hypercrosslinked monolithic columns.
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| 2. |
- Hemström, Petrus, et al.
(author)
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Polymer-based monolithic microcolumns for hydrophobic interaction chromatography of proteins.
- 2006
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In: Journal of Separation Science. - : Wiley. - 1615-9306 .- 1615-9314. ; 29:1, s. 25-32
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Journal article (peer-reviewed)abstract
- Monolithic capillary columns for hydrophobic interaction chromatography (HIC) have been prepared by thermally initiated, single-step in situ polymerization of mixtures of monovinyl monomers including butyl methacrylate and/or 2-hydroxyethyl methacrylate, with a divinyl crosslinker glycerol dimethacrylate or 1,4-butanediol dimethacrylate using two different porogen systems. Two porogenic solvent mixtures were used; one "hydrophilic", consisting of water, butanediol, and propanol, and one "hydrophobic," comprising dodecanol and cyclohexanol. The porous structures of the monoliths were characterized and their performance was demonstrated with a separation of a mixture of myoglobin, ribonuclease A, and lysozyme under conditions typical of HIC.
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| 3. |
- Nordborg, Anna, et al.
(author)
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Extending the array of crosslinkers suitable for the preparation of polymethacrylate-based monoliths
- 2005
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In: Journal of Separation Science. - : Wiley. - 1615-9306 .- 1615-9314. ; 28:17, s. 2401-2406
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Journal article (peer-reviewed)abstract
- The in situ preparation of monolithic capillary columns comprising copolymers of butyl methacrylate with ethylene dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, and pentaerythritol tetraacrylate using thermal polymerization within 250 mu m ID capillaries and their application for mu-HPLC separations of proteins has been studied. For all crosslinkers, optimization of the porogenic mixture consisting of 1-propanol and 1,4-butanediol yielded monoliths with pore sizes above 1 mu m suitable for rapid separations at low back pressure. Very good separations were achieved for a protein mixture consisting of ribonuclease A, cytochrome c, myoglobin, and ovalbumin with all tested columns.
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| 4. |
- Viklund, Camilla, et al.
(author)
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Preparation of Porous Poly(styrene-co-divinylbenzene) Monoliths with Controlled Pore Size Distributions Initiated by Stable Free Radicals and Their Pore Surface Functionalization by Grafting
- 2001
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In: Macromolecules. - : American Chemical Society (ACS). - 0024-9297 .- 1520-5835. ; 34:13, s. 4361-9
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Journal article (peer-reviewed)abstract
- A stable free radical (SFR) mediated preparation of porous poly(styrene-co-divinylbenzene) monoliths using new types of SFRs and a novel binary porogenic solvent consisting of poly(ethylene glycol) and 1-decanol has been studied. Polymerizations carried out in the presence of 3-carboxy-2,2,5,5-tetramethylpyrrolidinyl-1-oxy (3-carboxy-PROXYL) or 4-carboxy-2,2,6,6-tetramethylpiperidinyl-1-oxy (4-carboxy-TEMPO) were faster, and higher degrees of monomer conversions were achieved in a shorter period of time compared to the corresponding reactions mediated by 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO). The effect of the type of SFR (TEMPO, 3-carboxy-PROXYL, 4-carboxy-TEMPO, 4-amino-TEMPO, 4-acetamido-TEMPO, and 4-trimethylammonio-TEMPO iodide) on the pore size distribution was also investigated. The use of carboxy functional SFRs simultaneously accelerated the reaction kinetics, improved the permeability of the prepared monoliths, and enabled control of the porous properties of the monolithic polymers over a wide range simply by modifying the ratio of poly(ethylene glycol) 400 and 1-decanol in the porogenic mixture. The reinitiation capability of poly(styrene-co-divinylbenzene) monoliths capped with 3-carboxy-PROXYL or 4-carboxy-TEMPO moieties was utilized to perform in situ grafting of 2-hydroxyethyl methacrylate and 3-sulfopropyl methacrylate, resulting in monoliths with altered surface polarities.
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