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Porous Polyvinylidene Difluoride (PVDF) Monoliths via Thermally Induced Dissolution/Precipitation. Three Strategies to Pore-Tuning: Probing the possibilities of further controlling of the PVDF monolith pore formation process
Umeå University, Faculty of Science and Technology, Department of Chemistry. (Research Group for Reactive Polymers in Analytical Chemistry (RPAC))
Umeå University, Faculty of Science and Technology, Department of Chemistry. (Research Group for Reactive Polymers in Analytical Chemistry (RPAC))
(English)Manuscript (preprint) (Other academic)
Abstract [en]

The porous properties and morphologies of the PVDF monoliths prepared via thermally induced dissolution/precipitation process were proved to be adjustable, by employing several porogenic additives to the PVDF/n-butyl butyrate matrix. PVDF monoliths have been separately precipitated from; only the main diluent (n-butyl butyrate); mixtures of the main diluent and a co-diluent; binary polymer mixtures (including an additional porogenic polymer such as poly ethylene glycol PEG200, PEG400 and poly propylene glycol PPG425); and the main diluent in the presence of a fluoro-surfactant (FSO, FSN). Their meso- and macro-porous properties were characterized by nitrogen cryoption measurements (3-5 repeated runs per sample), and a subsequent single analysis by mercury intrusion porosimetry. The visual assessment of the monoliths morphology differences were carried out using scanning electron microscopy (SEM).

National Category
Chemical Sciences
Research subject
Analytical Chemistry
Identifiers
URN: urn:nbn:se:umu:diva-89313OAI: oai:DiVA.org:umu-89313DiVA: diva2:719791
Available from: 2014-05-27 Created: 2014-05-27 Last updated: 2014-05-28Bibliographically approved
In thesis
1. Porous Polymeric Monoliths by Less Common Pathways: Preparation and Characterization
Open this publication in new window or tab >>Porous Polymeric Monoliths by Less Common Pathways: Preparation and Characterization
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on my endeavors to prepare new porous polymeric monoliths that are viable to use as supports in flow-through processes. Polymer monoliths of various porous properties and different chemical properties have been prepared utilizing the thermally induced phase separation (TIPS) phenomenon and step-growth polymerization reactions. The aim has been to find appropriate synthesis routes to produce separation supports with fully controlled chemical, physical and surface properties. This thesis includes preparation of porous monolithic materials from several non-cross-linked commodity polymers and engineering plastics by dissolution/precipitation process (i.e. TIPS). Elevated temperatures, above the upper critical solution temperature (UCST), were used to dissolve the polymers in appropriate solvents that only dissolve the polymers above this critical temperature. After dissolution, the homogeneous and clear polymer-solvent solution is thermally quenched by cooling. A porous material, of three dimensional structure, is then obtained as the temperature crosses the UCST. More than 20 organic solvents were tested to find the most compatible one that can dissolve the polymer above the UCST and precipitate it back when the temperature is lowered. The effect of using a mixture of two solvents or additives (co-porogenic polymer or surfactant) in the polymer dissolution/precipitation process have been studied more in depth for poly(vinylidine difluoride) (PVDF) polymers of two different molecular weight grades. Monolithic materials showing different pore characteristics could be obtained by varying the composition of the PVDF-solvent mixture during the dissolute­ion/precipitation process. Step-growth polymerization (often called polycondensat­ion reaction) combined with sol-gel process with the aid of porogenic polymer and block copolymer surfactant have also been used as a new route of synthesis for production of porous melamine-formaldehyde (MF) monoliths. In general, the meso- and macro-porous support materials, for which the synthesis/preparation is discussed in this thesis, are useful to a wide variety of applications in separation science and heterogeneous reactions (catalysis).

Place, publisher, year, edition, pages
Umeå: Umeå university, 2014. 63 p.
Keyword
Monolith, commodity polymer, thermally induced phase separation, dissolution-precipitation, polymer solvents, porogenic polymer, step-growth polymerization, separation science, melamine-formaldehyde
National Category
Analytical Chemistry Polymer Chemistry Materials Chemistry
Identifiers
urn:nbn:se:umu:diva-89322 (URN)978-91-7601-088-4 (ISBN)
Public defence
2014-06-13, KB3B1, KBC-huset, Umeå universitet, Umeå, 13:00 (English)
Opponent
Supervisors
Available from: 2014-05-28 Created: 2014-05-27 Last updated: 2014-05-28Bibliographically approved

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