Graphene Oxide - Towards A Comprehensive Characterization Scheme
2015-09
Loading...
View/Download File
Persistent link to this item
Statistics
View StatisticsJournal Title
Journal ISSN
Volume Title
Title
Graphene Oxide - Towards A Comprehensive Characterization Scheme
Authors
Published Date
2015-09
Publisher
Type
Thesis or Dissertation
Abstract
Graphene oxide (GO) is a near-2D material derived via oxidation of graphite and exploited in nanocomposites and optoelectronics. Following a literature review, the modified Tour-Dimiev (MTD) method was singled out for making GO, with the introduction of modifications tailored towards producing large sheets by starting with a large graphite size, tuning the oxidation conditions, employing temperature control and a modified wash routine. The product was characterized using wide-angle x-ray diffraction, x-ray photoelectron and Raman spectroscopy, revealing near completeness of graphite conversion, high oxygen content of GO and a comparable degree of defects to literature reports on the same. We imaged MTD-GO via fluorescence quenching microscopy (FQM) and atomic force microscopy (AFM). We compared the analytical capabilities of the image analysis software ImageJ with MATLAB, introducing several MATLAB subroutines to mitigate image analysis issues. We image-analyzed MTD-GO, concluding that GO size and thickness are statistically uncorrelated and described by lognormal and normal distributions respectively. We demonstrated that AFM captures small particles better than FQM, and that these two techniques can be combined to obtain a complete picture of polydisperse sample size distributions. Next, we modeled polydisperse dilute dispersions of oblate spheroids and discs in shear, uniaxial and biaxial extension using microhydrodynamic models found in the literature. We used the shear model to fit experimental shear data on a number of serially diluted sheet dispersions to obtain the dimensions and distributions thereof. The systems analyzed were MTD-GO, commercial GO before and after sonication, and a literature dataset on aqueous layered double hydroxides. Finally, we conducted novel Langmuir trough experiments with MTD-GO to understand the mechanisms surrounding the air-water interfacial assembly of GO. We were able to successfully transfer our films from the air-water interface onto a simple and versatile substrate such as surface-treated glass. We correlated film morphology in situ using Brewster Angle Microscopy and ex situ through FQM imaging of Langmuir-Blodgett-coated glass slides, to the pressure-area isotherm. We established that film packing occurs at low surface pressures. Finally, we showed that GO shows weak, pH-dependent intrinsic surface activity.
Description
University of Minnesota Ph.D. dissertation. September 2015. Major: Chemical Engineering. Advisor: Christopher Macosko. 1 computer file (PDF); xiv, 193 pages.
Related to
Replaces
License
Collections
Series/Report Number
Funding information
Isbn identifier
Doi identifier
Previously Published Citation
Suggested citation
Ismail, Issam. (2015). Graphene Oxide - Towards A Comprehensive Characterization Scheme. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/183367.
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.