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Sum Frequency Generation Vibrational Spectroscopic Study of Methacrylate-based Monomers at the Solid-Liquid Interface and Polymer Thin Films at Air-Polymer and Polymer-Liquid Interfaces.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Sum Frequency Generation Vibrational Spectroscopic Study of Methacrylate-based Monomers at the Solid-Liquid Interface and Polymer Thin Films at Air-Polymer and Polymer-Liquid Interfaces./
Author:	Adhikari, Narendra M.
Description:	1 online resource (196 pages)
Notes:	Source: Dissertations Abstracts International, Volume: 84-01, Section: B.
Contained By:	Dissertations Abstracts International84-01B.
Subject:	Chemistry. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=29282644click for full text (PQDT)
ISBN:	9798802758892

Sum Frequency Generation Vibrational Spectroscopic Study of Methacrylate-based Monomers at the Solid-Liquid Interface and Polymer Thin Films at Air-Polymer and Polymer-Liquid Interfaces.
Adhikari, Narendra M.

Sum Frequency Generation Vibrational Spectroscopic Study of Methacrylate-based Monomers at the Solid-Liquid Interface and Polymer Thin Films at Air-Polymer and Polymer-Liquid Interfaces. - 1 online resource (196 pages)

Source: Dissertations Abstracts International, Volume: 84-01, Section: B.

Thesis (Ph.D.)--Ohio University, 2019.

Includes bibliographical references

The research work presented here utilizes the second order non-linear optical sum frequency generation (SFG) vibrational spectroscopy to study interfacial molecular organization. This spectroscopic technique is intrinsically selective to the anisotropic dipoles present at the interface. The main objective of this study is to investigate the molecular organization of the methacrylate-based monomers at both the hydrophilic and hydrophilic solid-liquid interface and thin films of the polymers at air-solid and air-liquid interfaces. The ethyl methacrylate monomers used in the study presented here have varied substituent groups at the ethyl group. Different types of substituents are introduced to study for example the effect of size or electronegativity of the substituents on the conformation of the monomers at the interface.This dissertation explores the effect of the bulky and the electronegative substituent groups on the organization of monomers at both the hydrophilic and hydrophobic solid-monomer interface. When the results of the monomers are compared to the results at the air-monomer interface, we found that the monomer conformation is different at the hydrophilic solid-interface. This difference can be due to a change of the environment and the existence of hydrogen bonding between carbonyl groups of the monomers and the silanol groups of the hydrophilic silica. The SFG signal from carbonyl groups of the monomer was found to be affected by the size and the electronegativity of the substituents. In general, the smaller the size or the weaker the electronegativity of the substituent group, the stronger is the carbonyl signal. Also, in the hydrophobic solid-monomer interface study, regardless of the nature of the substituents, no appreciable carbonyl signal was observed. This observation indicates that the surface silanol group provides hydrogen bonding avenues to the carbonyl groups of the monomers and hence, there is the net orientation of the carbonyl group at the interface. The strength of the hydrogen bonding is affected by the nature of the substituent groups.As an extension of the monomer studies, we also studied the organization of the polymer thin films at the air-thin film and thin film-liquid interfaces. The effect of sample preparation, as well as the exposure of the thin films with the liquids, were investigated. The solvents chosen for the spin coating polymer solution, as well as annealing time, was found to affect the organization of the polymer thin films. In addition, because of the structural complexity and convoluted spectra we also utilized the polarization mapping method (PMM) which provides ways to better assign the vibrational modes because the peak intensity in the SFG spectra is sensitive to the change in the polarization of the beams. The results were also compared with the results from the conventional polarization spectra. It is found out that the PMM not only help to assign the convoluted features in the spectra, this technique also complemented the orientational analysis using polarization intensity ratio (PIR) method.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798802758892Subjects--Topical Terms:

516420
Chemistry.
Subjects--Index Terms:

Sum Frequency GenerationIndex Terms--Genre/Form:

542853
Electronic books.

Sum Frequency Generation Vibrational Spectroscopic Study of Methacrylate-based Monomers at the Solid-Liquid Interface and Polymer Thin Films at Air-Polymer and Polymer-Liquid Interfaces.
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504 $a Includes bibliographical references
520 $a The research work presented here utilizes the second order non-linear optical sum frequency generation (SFG) vibrational spectroscopy to study interfacial molecular organization. This spectroscopic technique is intrinsically selective to the anisotropic dipoles present at the interface. The main objective of this study is to investigate the molecular organization of the methacrylate-based monomers at both the hydrophilic and hydrophilic solid-liquid interface and thin films of the polymers at air-solid and air-liquid interfaces. The ethyl methacrylate monomers used in the study presented here have varied substituent groups at the ethyl group. Different types of substituents are introduced to study for example the effect of size or electronegativity of the substituents on the conformation of the monomers at the interface.This dissertation explores the effect of the bulky and the electronegative substituent groups on the organization of monomers at both the hydrophilic and hydrophobic solid-monomer interface. When the results of the monomers are compared to the results at the air-monomer interface, we found that the monomer conformation is different at the hydrophilic solid-interface. This difference can be due to a change of the environment and the existence of hydrogen bonding between carbonyl groups of the monomers and the silanol groups of the hydrophilic silica. The SFG signal from carbonyl groups of the monomer was found to be affected by the size and the electronegativity of the substituents. In general, the smaller the size or the weaker the electronegativity of the substituent group, the stronger is the carbonyl signal. Also, in the hydrophobic solid-monomer interface study, regardless of the nature of the substituents, no appreciable carbonyl signal was observed. This observation indicates that the surface silanol group provides hydrogen bonding avenues to the carbonyl groups of the monomers and hence, there is the net orientation of the carbonyl group at the interface. The strength of the hydrogen bonding is affected by the nature of the substituent groups.As an extension of the monomer studies, we also studied the organization of the polymer thin films at the air-thin film and thin film-liquid interfaces. The effect of sample preparation, as well as the exposure of the thin films with the liquids, were investigated. The solvents chosen for the spin coating polymer solution, as well as annealing time, was found to affect the organization of the polymer thin films. In addition, because of the structural complexity and convoluted spectra we also utilized the polarization mapping method (PMM) which provides ways to better assign the vibrational modes because the peak intensity in the SFG spectra is sensitive to the change in the polarization of the beams. The results were also compared with the results from the conventional polarization spectra. It is found out that the PMM not only help to assign the convoluted features in the spectra, this technique also complemented the orientational analysis using polarization intensity ratio (PIR) method.
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