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Zwitterionic Copolymers for Fouling Resistant and Responsive Membranes
Başlık:
Zwitterionic Copolymers for Fouling Resistant and Responsive Membranes
Yazar:
Kaner, Papatya, author.
ISBN:
9780438020856
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (227 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 79-10(E), Section: B.
Advisors: Ayse Asatekin Committee members: Scott M. Husson; Matthew J. Panzer; Samuel W. Thomas III.
Özet:
Fouling is likely the most important obstacle to the use of membranes in many applications, especially in those that the feed contains high concentrations of organics such as oil and biomacromolecules. This thesis focuses on the use of zwitterionic copolymers, which are known to show excellent fouling resistance and hydrophilicity, to enhance the fouling resistance of ultrafiltration (UF) membranes and/or incorporate responsive features into these systems that can enable self-cleaning mechanisms.
One approach to incorporate these features into UF membranes is during their manufacture, by blending a commodity polymer with a zwitterion containing copolymer. We synthesized random copolymers incorporating two different zwitterionic groups, sulfobetaine methacrylate (SBMA) and sulfobetaine-2-vinylpyridine (SB2VP). We showed that, with the appropriate choice of parameters, zwitterionic additive content as low as 10 wt.% can lead to membranes with high flux and complete fouling resistance to oil suspensions and protein solutions.
We also studied the effect of the skeletal architecture of zwitterionic additives in membrane properties, by comparing zwitterionic copolymers with two different architectural structures, random and comb-shaped. We showed that both additives lead to a water permeance five times that of the additive free membrane. However, comb additive containing membrane exhibits a more prominent ionic strength responsive change in its surface nanostructure and permeance, in addition to its better resistance to oil fouling and protein adhesion.
As another approach, we developed a novel self-cleaning, photoresponsive membrane that is capable of removing pre-deposited foulant layers upon changes in surface morphology in response to UV or visible light irradiation. This membrane was prepared by coating a porous support membrane with a thin layer of a comb-shaped graft copolymer with photoreactive side-chains. Before any photo-treatment, the as-coated membrane allows the adsorption of organic solutes on its surface, reducing flow rate. Once exposed to UV light, conversion of hydrophobic spiropyran groups to hydrophilic merocyanine groups leads to the release of adsorbed molecules and full recovery of the initial water flux.
Lastly, we developed selective thin films whose morphology and function arise from the self-assembled nanostructure of the zwitterionic comb copolymers. Thin film morphology showed hierarchical features including 17 +/- 5 nm spherical micelles along with larger nanopores of 85 +/- 45 nm, which arose from the self-assembly of the copolymer in this bilayer system. In addition, the film proved ionic strength responsive permeation in ultrafiltration range with a pore density as high as 1013 pores/m2.
Notlar:
School code: 0234
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(680884.1) | 680884-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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