Chemical Studies of Coulombic Complexations in Polymers
Yau, Hwei-Ling
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https://hdl.handle.net/2142/71829
Description
Title
Chemical Studies of Coulombic Complexations in Polymers
Author(s)
Yau, Hwei-Ling
Issue Date
1986
Department of Study
Metallurgy and Mining Engineering
Discipline
Metallurgical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Metallurgy
Abstract
This research has involved chemical studies of complexes produced from coulombic interaction between a polymer and a monomeric ion (monoion) as well as between two polyions. For the polymer-monoion complexation, a poly(crown ether) (PCE), is studied in the form of an ion-doped polymer. The experimental work was aimed at understanding the significant changes brough about by ion-doping including not only the molecular conformations of polymer chains but also the solution properties and physical properties of polymer films.
Results suggest that chains form helical tunnels by ion-doping. The glass transition temperature of films cast from solution were found to increase with the concentration of barium triflate, and their electrical conduction was found dependent not only on the concentration of barium salt but possibly on the concentration of chemical defects in PCE chains as well. The conductivity was observed to have a maximum at low concentration of salt which is also observed in other ion-polymer complex systems. However, it was observed for the first time that conductivity can increase again at high concentration of salt and in some cases exceed the value in the previous maximum. The polyion complexes were studied through the novel system of interpolymer coulombic association between an electronically doped conductive polymer (either n- or p-doped) and a polyelectrolyte. The experimental concept has been the electronic doping of a conductive polymer stabilized by an organic polymer as the counterion (poly-counterion) in media leading to coulombic complexation. Several chemical systems were specially designed for the study, using poly(p-phenylene) (PPP) as the precursor of a conductive polymer. Research indicates the chemical characterization and physical properties of materials produced from complexations a well as conduction measurements of solid complexes. The PCE solution in toluene was found to be effectively doped by the electron-donor based on electron paramagnetic resonance measurements. In the system of potassium metal (K(DEGREES)) doping of PPP in PCE solution, PPP seemed to behave as a solid catalyst for the electron transfer reaction from K(DEGREES) to PCE solution. The system of doping PPP with K(DEGREES) in ethylenediamine followed by the complexation with an ionene was found to disperse, swell or partially dissolve PPP. The ionic conductivity of the coulombic complex produced from this chemical system was enhanced by two orders of magnitude presumably due to the presence of electronically conductive structure of PPP. During the course of this research, two new doping techniques for PPP were developed in the laboratory. (Abstract shortened with permission of author.)
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