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A study of surface modification and anchoring techniques used in the preparation of monolithic microcolumns in fused silica capillaries.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Chemistry.
Umeå University, Faculty of Science and Technology, Department of Physics.
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2006 (English)In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 29, no 1, 14-24 p.Article in journal (Refereed) Published
Abstract [en]

Based on a survey of the literature on pretreatment of fused silica capillaries, 3 etching procedures and 11 silanization protocols based on the vinylic silane 3-((trimethoxysilyl)propyl) methacrylate (gamma-MAPS) were found to be most representative as a means of ensuring attachment of in situ prepared vinylic polymers. These techniques were applied to fused silica capillaries and the success in establishing the intended surface modification was assessed. X-ray photoelectron spectroscopy (XPS) was used to characterize the chemical state of the surface, providing information regarding presence of the reagent bound to the capillary. Wetting angles were measured and correlated with the XPS results. An adherence test was done by photopolymerization of a 2 mm long plug of 1,6-butanediol dimethacrylate in the prepared capillaries and evaluation of its ability to withstand applied hydraulic pressure. SEM was also performed in cases where the plug was released or other irregularities were observed. Finally, the roughness of the etched surface, considered to be of importance, was assessed by atomic force microscopy. Alkaline etching at elevated temperature provided a surface roughness promoting adhesion. The commonly used silanization protocols involving water in the silanization or washing steps gave inadequate surface treatment. The best silanization procedure was based on toluene as a solvent.

Place, publisher, year, edition, pages
Wiley , 2006. Vol. 29, no 1, 14-24 p.
Keyword [en]
Capillary columns, Fused silica capillary, Monoliths, Surface modification
Identifiers
URN: urn:nbn:se:umu:diva-11145DOI: 10.1002/jssc.200500294PubMedID: 16485705OAI: oai:DiVA.org:umu-11145DiVA: diva2:150816
Available from: 2008-03-27 Created: 2008-03-27 Last updated: 2015-09-28Bibliographically approved
In thesis
1. Porous polymeric materials for chromatography: Synthesis, functionalization and characterization
Open this publication in new window or tab >>Porous polymeric materials for chromatography: Synthesis, functionalization and characterization
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background: Separation science is heavily reliant on materials to fulfill ever more complicated demands raised by other areas of science, notably the rapidly expanding molecular biosciences and environmental monitoring. The key to successful separations lies in a combination of physical properties and surface chemistry of stationary phases used in liquid chromatographic separation, and this thesis address both aspects of novel separation materials.

Methods: The thesis accounts for several approaches taken during the course of my graduate studies, and the main approaches have been i) to test a wild-grown variety of published methods for surface treatment of fused silica capillaries, to ascertain firm attachment of polymeric monoliths to the wall of microcolumns prepared in silica conduits; ii) developing a novel porogen scheme for organic monoliths including polymeric porogens and macromonomers; iii) evaluating a mesoporous styrenic monolith for characterization of telomers intended for use in surface modification schemes and; iv) to critically assess the validity of a common shortcut used for estimating the porosity of monoliths prepared in microconduits; and finally v) employing plasma chemistry for activating and subsequently modifying the surface of rigid, monodisperse particles prepared from divinylbenzene.

Results: The efforts accounted for above have resulted in i) better knowledge of the etching and functionalization parameters that determine attachment of organic monoliths prepared by radical polymerization to the surface of silica; ii) polar methacrylic monoliths with a designed macroporosity that approaches the desired "connected rod" macropore morphology; iii) estab¬lishing the usefulness of monoliths prepared via nitroxide mediated polymerization in gradient polymer elution chromatography; iv) proving that scanning electron microscopy images are of limited value for assessing the macroporous properties of organic monoliths, and that pore measurements on externally polymerized monolith cocktails do not represent the porous properties of the same cocktail polymerized in narrow confinements; and v) showing that plasma bromination can be used as an activation step for rigid divinylbenzene particles to act as grafting handles for epoxy-containing telomers, that can be attached in a sufficiently dense layer and converted into carboxylate cation exchange layer that allows protein separations in fully aqueous eluents.

Place, publisher, year, edition, pages
Umeå: Kemiska Institutionen, Umeå universitet, 2009. 45 p.
Keyword
porous polymer monolith, pore size distribution, nitrogen sorptiometry, mercury intrusion porosimetry, scanning and transmission electron microscopy, plasma functionalization
National Category
Analytical Chemistry Analytical Chemistry Polymer Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-30314 (URN)978-91-7264-934-7 (ISBN)
Public defence
2010-01-15, KBC-Huset, KB3A9, Umeå Universitet, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2009-12-18 Created: 2009-12-16 Last updated: 2017-05-18Bibliographically approved
2. Monolithic separation media synthesized in capillaries and their applications for molecularly imprinted networks
Open this publication in new window or tab >>Monolithic separation media synthesized in capillaries and their applications for molecularly imprinted networks
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis describes the synthesis of chromatographic media using several different approaches, their characterizations and applications in liquid chromatography. The steps to achieve a separation column for a specific analyte are presented. The main focus of the study was the design of novel molecularly imprinted polymers.

Attachment of monolithic polymeric substrates to the walls of fused silica capillaries was studied in Paper I. With a broad literature survey, a set of common methods were tested by four techniques and ranked by their ability to improve anchoring of polymers. The best procedure was thus used for all further studies.

Synthesis of monoliths in capillary columns was studied in Paper II. With the goal of separating proteins without denaturation, various monoliths were polymerized in situ using a set of common monomers and cross-linkers mixed with poly(ethylene glycol) as porogen. The resulting network was expected to present “protein-friendly pores”. Chemometrics were used to find and describe a set of co-porogens added to the polymerization cocktails in order to get good porosity and flow-through properties.

Assessment of the macroporous structure of a monolith was described in Paper III. An alternative method to mercury intrusion porosimetry was proposed. The capillaries were embedded in a stained resin and observed under transmission electron microscope. Images were then computed to determine the pore sizes.

Synthesis of molecularly imprinted polymers grafted to a core mono-lith in a capillary was described in Paper IV. The resulting material, imprinted with local anaesthetics, was tested for its chromatographic performance. Similar imprinted polymers were characterized by microcalorimetry in Paper V. Finally, imprinted monoliths were also synthesized in a glass tube and further introduced in a NMR rotor to describe the interactions between stationary phase and template in Paper VI.

Place, publisher, year, edition, pages
Umeå: Kemi, 2006. 50 p.
Keyword
bupivacaine, etching, phosphorylated tyrosine, poly(ethylene glycol), silanization, transmission electron microscopy, fused silica capillaries, isothermal titration calorimetry, local anæsthetic, molecularly imprinted polymer, monolith, nuclear magnetic resonance
National Category
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-923 (URN)91-7264-207-6 (ISBN)
Public defence
2006-12-01, Lilla Hörsallen KB3A9, KBC-Huset, Umeå University, Umeå, Sweden, 10:00
Opponent
Supervisors
Available from: 2006-11-10 Created: 2006-11-10 Last updated: 2011-04-15Bibliographically approved

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Byström, EmilIwasiewicz, AgnieszkaShchukarev, AndreyIrgum, Knut

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