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Techniques to improve the graphitization of lignin, the second most abundant natural polymer, are in great demand as a viable means to obtain cost- effective and less energy-intensive graphite for various applications. In this work, we report the effects of two-dimensional nanomaterials, graphene oxide (GO) and its derivative, reduced graphene oxide (RGO), used as templating agents for the graphitization of alkali-derived lignin. The hypothesis is that during heat temperature treatment, the GO additives act as a template that allows the lignin matrix to align on its basal planes through π−π interactions. In addition, possible chemical bonding between the GO additives and lignin may extend the two planar frameworks. Results from X-ray diffraction and Raman spectroscopy showed improved graphitic quality in the lignin-GO and lignin-RGO samples compared to pure lignin at 2500 °C. Transmission electron microscopy images and selected area electron diffraction patterns also revealed ordered nanostructures and defined polycrystalline patterns in the lignin-GO and lignin-RGO samples. This work presents a method to synthesize graphitic-like materials using carbon-based templates with the advantage that there is no need for further purification of the final material as in the case of transition metal catalysts.
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The Role of Reduced Graphene Oxide toward the Self-Assembly of Lignin-Based Biocomposites Fabricated from Ionic Liquids
Lignin’s immiscibility with most polymers along with its unknown association behaviors are major factors that contribute to its disposal and processability for the production of materials. To fully utilize lignin, an improved understanding of its interaction with other materials is needed. In this study, we investigate the morphological and physicochemical properties upon the addition of reduced graphene oxide (rGO) as a function of material composition in a tertiary system comprised of lignin, cellulose and xylan. The main motivation for this work is to understand how the lignin molecule associates and behaves in the presence of other natural macromolecules, as well as with the addition of reduced graphene oxide. The fabricated biocomposites with and without rGO were investigated using Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), Scanning Electron Microscope (SEM) techniques, Thermogravimetric Analysis (TGA), and Differential Scanning Calorimetry (DSC). The results demonstrated that the regenerated films’ structural, morphological and thermal character changed as a function of lignin-xylan concentration and upon the addition of rGO. We also observed a dramatic change in the glass transition temperature and topography. Final analysis showed that the addition of rGO prevented the macromolecules to self-assemble through a reduction of π-π aggregations and changes in the cellulose crystallinity.
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- Award ID(s):
- 1809354
- PAR ID:
- 10092368
- Date Published:
- Journal Name:
- International Journal of Molecular Sciences
- Volume:
- 19
- Issue:
- 11
- ISSN:
- 1422-0067
- Page Range / eLocation ID:
- 3518
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/ijms19113518
