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New approaches to preparation of macroporous monoliths for use in liquid chromatography
Umeå University, Faculty of Science and Technology, Department of Chemistry.
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

High performance liquid chromatography (HPLC) is one of the major techniques in separat-ion sciences. Faster separation and higher efficiency are required to meet ever-growing demands. Despite numerous studies and achievements on improving mass transfer in particulate packings discontinuity seems to be the cornerstone drawback in their development. Macroporous continuous beds or monoliths are therefore a promising alternative to the particle medium. This thesis deals with preparation of new monoliths used as carrier for HPLC. Two different approaches were developed for two polymer systems. One was based on polycondensation of epoxy resins and polyamines which were components of an oil-in-water emulsion. An epoxy resin mixture was dispersed in aqueous polyamine phase with the aid of a surfactant. The other involved a traverse of a ready-made polymer solution around its upper critical solution temperature (UCST). In other words, linear polyamides, non-covalently crosslinked polymers, dissolved in a solvent at temperature higher than their UCST followed by slow cooling to below the critical temperature to precipitate the polymers. Partly re-established hydrogen bonds resulted in the formation of crystallites that interconnected into a network structure. Factors controlling morphology and porosity of final products were investigated. The study also deals with surface modifying for chromatographic applications. Functionalization pathways attempted in the thesis were quaterization of inherent amine of the epoxy-based monoliths and grafting tentacle ion groups via glycidyl methacrylate by atom transfer radical polymerization (ATRP) for ion exchange chromatography (IEC).

Place, publisher, year, edition, pages
Umeå: Umeå University, Department of Chemistry , 2009. , 53 p.
Keyword [en]
monolith, polycondensation, dissolution-precipitation, epoxy-amine, poly-amide, nylon, emulsion polymerization, characterization, protein separation, liquid chromatography
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
URN: urn:nbn:se:umu:diva-20890ISBN: 978-91-7264-772-5 (print)OAI: oai:DiVA.org:umu-20890DiVA: diva2:209822
Distributor:
Kemiska institutionen, 90187, Umeå
Public defence
2009-04-17, KB3A9, Umeå University, Chemistry, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2009-03-30 Created: 2009-03-27 Last updated: 2014-03-10Bibliographically approved
List of papers
1. Epoxy-Based Monoliths. A Novel Hydrophilic Separation Material for Liquid Chromatography of Biomolecules
Open this publication in new window or tab >>Epoxy-Based Monoliths. A Novel Hydrophilic Separation Material for Liquid Chromatography of Biomolecules
2006 (English)In: Chemistry of Materials, Vol. 18, no 26, 6308-15 p.Article in journal (Refereed) Published
Abstract [en]

In our efforts to develop novel hydrophilic monolithic porous materials for use as supports in liquid chromatographic separation of proteins, polymers based on epoxy monomers and diamines as curing agents were synthesized. The epoxy dispersed phase was emulsified in an aqueous phase containing the amine with the aid of a nonionic polymeric surfactant, and the resulting emulsions were thermally polymerized. Various factors, namely, the type of epoxy component, levels of reactants, type and concentration of diluents, and curing procedures, were studied to obtain suitable morphology and adequate mechanical properties for their intended use. Characterization of their morphologies and porous properties was done using scanning electron microscopy, nitrogen adsorption/desorption measurement (BET method), mercury intrusion porosimetry, and X-ray photoelectron spectroscopy.

Identifiers
urn:nbn:se:umu:diva-12507 (URN)doi:10.1021/cm060645j (DOI)
Available from: 2007-04-10 Created: 2007-04-10 Last updated: 2011-01-11Bibliographically approved
2. Sizeable Macroporous Monolithic Polyamide Entities Prepared in Closed Molds by Thermally Mediated Dissolution and Phase Segregation
Open this publication in new window or tab >>Sizeable Macroporous Monolithic Polyamide Entities Prepared in Closed Molds by Thermally Mediated Dissolution and Phase Segregation
2008 (English)In: Chemistry of Materials, Vol. 20, no 19, 6244-7 p.Article in journal (Refereed) Published
Abstract [en]

A simple method is presented for the preparation of macroporous monoliths from an aliphatic polyamide in closed molds, based on swelling/dissolution in benzyl alcohol at elevated temperature, followed by precipitation into a continuous monolithic structure by cooling the solution below the upper critical solution temperature. Subsequent removal of the solvent led to the formation of rigid macroporous nylon monoliths with a continuous and evenly spaced macropore system. The intended use is as supports for flow-through systems, where efficient mass transport at low flow resistance is the key optimization criterion.

Identifiers
urn:nbn:se:umu:diva-10615 (URN)doi:10.1021/cm800088a (DOI)
Available from: 2008-10-07 Created: 2008-10-07 Last updated: 2011-01-10Bibliographically approved
3. Preparation and characterization of sizable macroporous epoxy resin-based monolithic supports for flow-through systems
Open this publication in new window or tab >>Preparation and characterization of sizable macroporous epoxy resin-based monolithic supports for flow-through systems
Show others...
2009 (English)In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 32, no 15-16, 2608-2618 p.Article in journal (Refereed) Published
Abstract [en]

This paper presents further results from our efforts to prepare sizable macroporous monolithic materials from epoxy resins and polyamines by emulsion polymerization. For their uses as supports in flow systems, the study aimed at developing materials possessing maximum fluid permeability, high mechanical stability, and a controlled porosity and surface area. Characterization of the materials has been carried out using different techniques, focusing on morphological and mechanical features, and on the surface chemistry. Morphology and porosity were studied with SEM, nitrogen adsorption/desorption, mercury intrusion porosimetry (MIP), and (2)H NMR cryoporosimetry. The chemical composition of the bulk structures and their surfaces was studied by means of bulk elemental analysis and X-ray photoelectron spectroscopy, and potentiometric titration was used to assess the relative amounts of amines and epoxy groups. Essentially, the morphological features were a high fluid permeability, but rather low specific surface area. Convective flow was facilitated by large, interconnected, and evenly spaced macropores which were formed by nonporous skeletons of the connected-rod type. Despite the interfacial nature of the polymerization, the bulk and the surface of the fully cured materials showed similar elemental compositions. All materials were found to have a high surface density of hydroxyl groups, which facilitates functionalization reactions.

Place, publisher, year, edition, pages
Wiley InterScience, 2009
Keyword
Characterization, Chromatography, Condensation polymerization, Epoxy-amine, Macroporous, Monolithic sorbents
National Category
Chemical Sciences
Identifiers
urn:nbn:se:umu:diva-25954 (URN)10.1002/jssc.200900242 (DOI)19670275 (PubMedID)
Available from: 2009-09-15 Created: 2009-09-15 Last updated: 2017-12-13Bibliographically approved
4. Thermally induced dissolution/precipitation: A simple approach for the preparation of Macroporous Monoliths from Linear Aliphatic Polyamides
Open this publication in new window or tab >>Thermally induced dissolution/precipitation: A simple approach for the preparation of Macroporous Monoliths from Linear Aliphatic Polyamides
2009 (English)In: Journal of Separation Science, ISSN 1615-9306, E-ISSN 1615-9314, Vol. 32, no 15-16, 2619-2628 p.Article in journal (Refereed) Published
Abstract [en]

A versatile way of preparing macroporous monolithic materials from linear aliphatic polyamides is presented. Simply, polyamide pellets were treated in benzyl alcohol (BA) at elevated temperature, causing dissolution by interchain hydrogen bond disruption. Subsequent cooling below the upper critical solution temperature (UCST) resulted in precipitation and partial restoration of the semicrystalline polymer, which is organized into network structures. The final steps were a solvent exchange of BA for methanol, followed by drying to form monolithic entities. A number of polyamides ranging from hydrophilic to hydrophobic were tested and under the experimental conditions, poly(1-aza-2-cycloheptanone (PA6) and (poly-[imino-1,6-hexanediylimino{1,10-dioxo-1,10-decanediyl}] (PA610) yielded entities with macroporous properties that were deemed useful for liquid chromatography. The morphological features and porous properties of the monoliths produced by this dissolution-precipitation procedure were studied by scanning electron microscopy, adsorption/desorption of N2(g) according to the Brunauer-Emmett-Teller (BET) principle, and mercury intrusion porosimetry. Degradation of the polymer backbone was noticeable when the dissolution time was extended and shortening of the polymer chains was confirmed by MALDI-MS, viscosity measurements, X-ray photoelectron spectroscopy (XPS), and potentiometric titration. When the heating was limited to the time it took to dissolve the polymers, mechanically stable monoliths could be obtained. The dissolution/heat treatment time further seemed to be useful for controlling the macroporous morphology.

Place, publisher, year, edition, pages
Wiley InterScience, 2009
Keyword
Dissolution, Non-acidic solvent, Nylon, Polyamides, Polymer degradation, Porous monoliths, Precipitation, Upper critical solution temperature (UCST)
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-20888 (URN)10.1002/jssc.200900241 (DOI)
Available from: 2009-03-27 Created: 2009-03-27 Last updated: 2017-12-13Bibliographically approved
5. Functionalization of epoxy-based monoliths for ion exchange chromatography of proteins
Open this publication in new window or tab >>Functionalization of epoxy-based monoliths for ion exchange chromatography of proteins
Show others...
2009 (English)In: Journal of Separation Science, Vol. 32, no 15-16, 2556-2564 p.Article in journal (Refereed) Published
Abstract [en]

Macroporous epoxy-based monoliths prepared by emulsion polymerization have been modified for use in ion exchange chromatography (IEC) of proteins. Strong anion exchange functionality was established by iodomethane quaternization of tertiary amine present on the monolith surface as a part of the polymer backbone. The modification pathway to cation exchange materials was via incorporation of glycidyl methacrylate (GMA) brushes which were coated using atom transfer radical polymerization (ATRP). Strong (SO3-) and weak (COO-) cation exchange groups were thereafter introduced onto the GMA-grafted monoliths by reactions with sodium hydrogen sulfite and iminodiacetic acid, respectively. Grafting was confirmed by XPS, gravimetric measurement, and chromatographic behavior of the modified materials toward model proteins. In incubation experiments the proteins were recovered quantitatively with no obvious signs of unfolding after contact with the stationary phase for >2 h. Chromatographic assessments on the functionalized columns as well as problems associated with flow-through modification by ATRP are discussed.

Place, publisher, year, edition, pages
Wiley InterScience, 2009
Keyword
ATRP, Epoxy-amine, Ion exchange chromatography, Monolithic sorbents, Protein separation
National Category
Analytical Chemistry
Research subject
Analytical Chemistry
Identifiers
urn:nbn:se:umu:diva-20889 (URN)10.1002/jssc.200900243 (DOI)
Available from: 2009-03-27 Created: 2009-03-27 Last updated: 2012-05-10Bibliographically approved

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