Chemistry Commons^™

The Influence Of Ion-Ion Correlations On Conductivity In Concentrated Ionic Systems, Md Dipu Ahmed

Masters Theses

This study delves into the fascinating realm of concentrated ionic systems, such as ionic liquids, superionic materials, organic ionic plastic crystals, and polyelectrolytes, which hold immense potential for energy storage applications. The focus is on understanding the intricate role of ionic correlations in shaping their ionic conductivity behavior. These correlations can either boost or impede conductivity, yet their underlying mechanisms remain elusive. Through extensive investigation of various materials, including ionic liquids with differing anionic masses, pure organic ionic plastic crystals, and doped systems, this research employs advanced techniques like dielectric spectroscopy and innovative momentum conservation models to quantify these correlations. …

A Conductivity Analysis Of A Newly Synthesized Poly(Ethylene Glycol) Methyl Ether Hydroxide Electrolyte, Sarah Marie Peterson

Honors Theses

This thesis investigates the synthesis and conductive properties of a Poly (ethylene glycol) methyl ether-based polymer electrolyte. The goal of the synthesis is to enhance the hydroxide ion conduction properties of the polymer with its cationic groups attached. The MePEG backbone contained seven ethylene glycol groups and was modified to substitute the hydroxide group in the MePEG with trimethylamine. In addition, the bromide added in the synthesis was exchanged for hydroxide ions to allow for the transportation of hydroxide ions in polymeric electrolytes that can be used in Anion Exchange Membrane Fuel Cells. The newly synthesized polymer was compared to …

Effect Of Precise Control Of Crosslink Density On The Thermal, Mechanical, And Conductive Properties Of Covalently Crosslinked Ionene Networks, Alexander Thome

Honors College Theses

Ionic liquids (ILs), besides being well known as environmentally friendly solvents, have attracted attention for a wide variety of other applications, including gas separation, 3D-printing and electrochemical actuators. However, for many such applications, incorporation of the IL moiety into a polymeric material eliminates the use of mechanically unstable free ILs while maintaining many of their electrochemical benefits. Such polymers can take two basic forms: poly(ionic liquid)s are ion-containing polymers in which the IL group is attached pendant to the polymeric backbone, while ionenes are ion-containing polymers in which the IL group is anchored directly into the backbone of the repeating …

Properties And Applications Of Tetraalkylphosphonium Alkylsulfate Ionic Liquids And 3d Printed Polymerized Ionic Liquids, Mustafa Mohammed Alhussain

Murray State Theses and Dissertations

Ionic liquids (ILs) are defined as pure salts with a melting temperature below 100 °C with a subset called room-temperature ILs (RTILs) with melting temperatures at or below room temperature. The sizes of the cation and anion play a critical role in determining the properties, with smaller ions forming stronger ionic forces and packing better, raising viscosity and lowering conductivity of the IL. At the same time, intermolecular forces such as van der Waals and hydrogen bonding can play a role in IL properties as well. Our research described herein is focused on three tetraalkylphosphonium-based cations coupled with three alkylsulfate …

Electropolymerization Of Polyaniline In The Presence Of Ferricyanide: Electrochemical, Spectroscopic And Gravimetric Studies, Lucas Marinelli

Master's Theses

In this work, ferricyanide-doped polyaniline (PANI) is electropolymerized by constant current and cyclic voltammetry (CV) measurements with simultaneous monitoring of mass changes using electrochemical quartz crystal microbalance (eQCM). Raman spectroscopy, Fourier transform infrared spectroscopy and CV measurements confirm the incorporation of the ferricyanide into the film and indicate modified electrical conductivity. UV-Vis absorbance spectroscopy and Raman spectroscopy confirm the conducting ‘emeraldine-salt’ state and confirm the presence of polarons, i.e. charge carriers.

The addition of ferricyanide during electropolymerization of the PANI film results in an increase of polymerization rate as confirmed using eQCM. A decrease in counter ion ingress/egress and an …

Synthesis And Characterization Of Polymeric Anion Exchange Membranes, Wenxu Zhang

Doctoral Dissertations

As alkaline anion exchange membrane fuel cells (AAEMFC) are regarded as promising and important energy devices, the development of high performance anion exchange membranes are in urgent need, as well as fundamental investigation on the structure-property relationship, which are the motivation of this dissertation. Three different polymer systems are presented and focused on polymer synthesis, material morphology, and ion transport phenomena. Crosslinked membranes are promising as practical materials, however, the understanding and further improvement of its performance is hindered by the lack of an ordered morphology or well-defined chemical structure. In Chapter 2, a series of crosslinked membranes were design …

Correlating Morphology To Performance In Conjugated Polymer Nanocomposite Thin Films, Siddharth Pradhan

Masters Theses

The morphology and performance of thin films that consist of conjugated polymers and nanoparticles are investigated in this thesis. In the first system, the morphology of the nanocomposite that consists of low band gap alternating copolymers with a methano-fullerene are determined by neutron scattering and correlated to their photovoltaic performance as polymer solar cells. These results show that the conjugated alternating copolymers have high miscibility relative to other conjugated polymers. The analysis of the scattering data shows that the morphology of the conjugated polymer-fullerene bulk heterojunction can be described as the formation of aggregates on two length scales. Important parameters …

Computational Studies Of Ion Transport In Polymer Electrolytes, Hui Wu

Doctoral Dissertations

Improving ionic conductivity and lithium mobility in polymer electrolytes is important for their practical use for battery electrolytes. In this study, a combination of molecular dynamics and Monte Carlo simulations was used to bring insight into lithium ion transport in poly(ethylene oxide) (PEO) with plasticizers and also next to alumina solid surface doped with lithium salt. The simulations were performed using a moderately high molecular weight polymer (Mn = 10,000 g/mol) at an EO:Li ratio of 15. For the plasticized system, the PEO with LiN(CF3SO 2)2 (LiTFSI) was mixed with 10 wt% plasticizers that included either cyclic ethylene carbonate …