Exfoliated zeolite sheets and block copolymers as building blocks for composite membranes.
2009-08
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Exfoliated zeolite sheets and block copolymers as building blocks for composite membranes.
Authors
Published Date
2009-08
Publisher
Type
Thesis or Dissertation
Abstract
Mixed matrix materials, comprising of zeolites incorporated in suitable matrix (polymeric or inorganic), are promising as future membrane materials with high permselectivity. However, they suffer from the drawback of low productivity due to increase in the membrane thickness by incorporation of micron-sized zeolites crystals as well as the low-permeability matrices employed currently. Nanocomposite membranes, consisting of thin zeolite sheets (~2 nm) embedded in an appropriate matrix, can provide a solution to this problem. This thesis addresses some of the material challenges to make such nanocomposite membranes.
A high permeability polymer was synthesized by combining the glassy polystyrene (PS) with the rubbery polydimethylsiloxane (PDMS) in a block copolymer architecture. The mechanical toughness of the material was optimized to facilitate the fabrication of thin free standing films and its gas transport properties were evaluated. The PS-PDMS-PS triblock copolymers were successfully hydrogenated for the first time to obtain the PCHE-PDMS-PCHE triblock copolymers (PCHE stands for polycyclohexylethylene). The hydrogenation reaction proceeded without any polymer chain breaking and the resultant polymer showed some interesting, rather unexpected thermodynamic properties. These polymeric materials are potentially useful as the matrix of nanocomposite membranes.
Highly crystalline zeolite sheets were obtained by exfoliation of zeolite lamellae. Preservation of crystal morphology and pore structure, which presents a major challenge during the exfoliation process, was successfully addressed in this work by judicious choice of operating conditions. Lamellae were exfoliated by surfactant intercalation and subsequently melt processing with polymers, resulting in polymer nanocomposites containing thin zeolite sheets (~2.5 nm) with well preserved pore structure. A method to obtain polymer-free exfoliated sheets was also developed to facilitate the fabrication of inorganic composite membranes. These zeolite sheets can be used as the selectivity-enhancement additive in composite membranes.
Description
University of Minnesota Ph.D. dissertation. August 2009. Major: Chemical Engineering. Advisors: Frank S. Bates and Michael Tsapatsis. 1 computer file (PDF); xi, 114 pages.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Maheshwari, Sudeep. (2009). Exfoliated zeolite sheets and block copolymers as building blocks for composite membranes.. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/55574.
Content distributed via the University Digital Conservancy may be subject to additional license and use restrictions applied by the depositor. By using these files, users agree to the Terms of Use. Materials in the UDC may contain content that is disturbing and/or harmful. For more information, please see our statement on harmful content in digital repositories.