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Insights into the Role of Structural Modification on the Surface Molecular Interactions Probed Using Sum Frequency Generation Spectroscopy

Premadasa, Uvinduni I
http://orcid.org/0000-0003-0289-2965
http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1578394424376667

Abstract Details

2020, Doctor of Philosophy (PhD), Ohio University, Chemistry and Biochemistry (Arts and Sciences).
Investigating the specific local environment and molecular interactions at liquid surfaces is crucial in comprehending physical, chemical, and biological processes. Probing the interfacial molecular conformations will provide an insight into the relationship between surface structure and the governing interactions at the surface. Herein, this dissertation used the approach of the effect of substituents on the interfacial conformation of a methacrylate backbone, to observe such surface structure interaction relationships. The ethyl end of the methacrylate monomer was substituted with bulky groups and electron-withdrawing groups. These substituted monomers were synthesized via nucleophilic addition elimination reaction and characterized using sum frequency generation (SFG) spectroscopy at the air-liquid interface. The spectroscopic results were correlated with surface tension measurements and the overall dipole moment of the molecules. The presence of bulky substituents affected the orientation distribution of the interfacial molecules. On the other hand, in the presence of electron-withdrawing groups, the intensity of vibrational modes was affected, suggesting the changes in interfacial molecular conformations and existing intermolecular interactions. In another project, quaternary ammonium surfactants were utilized to assess their conformation and orientation at the air-water interface using SFG spectroscopy. Herein, the approach of solvent isotopic substitution was used to investigate the surfactant water interactions. The results showed the addition of deuterated water rearranges its head group parallel to the interface and straightens its chain with reduced gauche defects. The change in the conformation of the surfactant molecules at the air-liquid interface showcased the difference in intermolecular interactions for water and deuterated water. In summary, these studies revealed the importance of SFG spectroscopy as a tool to probe surface structures in gauging molecular interactions and physiochemical properties at the air-liquid interface.
Katherine Cimatu (Advisor)
273 p.
Chemistry; Molecules; Optics; Physical Chemistry; Polymers
Sum frequency generation spectroscopy; Air liquid interface; Methacrylate monomers; Substitution effect; Cationic surfactants; Molecularly imprinted polymers; Interfacial conformations; Surface Molecular Interactions

Recommended Citations

Citations

  • Premadasa, U. I. (2020). Insights into the Role of Structural Modification on the Surface Molecular Interactions Probed Using Sum Frequency Generation Spectroscopy [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1578394424376667

    APA Style (7th edition)

  • Premadasa, Uvinduni. Insights into the Role of Structural Modification on the Surface Molecular Interactions Probed Using Sum Frequency Generation Spectroscopy. 2020. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1578394424376667.

    MLA Style (8th edition)

  • Premadasa, Uvinduni. "Insights into the Role of Structural Modification on the Surface Molecular Interactions Probed Using Sum Frequency Generation Spectroscopy." Doctoral dissertation, Ohio University, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1578394424376667

    Chicago Manual of Style (17th edition)

ohiou1578394424376667
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This open access ETD is published by Ohio University and OhioLINK.
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