Thesis (Ph.D.)--Brown University, 2008. / Vita. Advisor : Brian Moulton. Includes bibliographical references.

No description available.

Commercially important superabsorbent polymers are crosslinked polymers of partially neutralised acrylic acid which can typically absorb and retain up to a hundred times their own weight in water. Superabsorbent polymers are most widely used in the personal hygiene industry where they are found in the core of disposable nappies, external feminine sanitary products and adult incontinence pads as absorbents for bodily fluids. Many other applications have been found through their amazing absorptive properties including artificial snow, artificial muscles and the prevention of water leakage into underground transmission cables. Superabsorbent polymers have many important industrial uses although little investigation into their structure and mechanisms has been done to date. As a result of superabsorbent polymers being totally insoluble in all NMR solvents solid state 13C CP/MAS NMR was used to investigate various structural aspects of the polymer in both dry and hydrated states. The NMR work carried out on the structure of the superabsorbent polymers suggests differences in structure between polymers neutralised before and after polymerisation takes place. It also suggests different tacticity within the polymer, seen as the polymer becomes more hydrated. 23Na relaxational studies have given an insight into the change in the sodium ion environment as the polymer becomes more hydrated. The effect of increasing neutralisation of the polymer was also investigated. Nuclear Magnetic resonance imaging was also used to try and investigate the mechanism of absorption of liquid by the polymer. From the images produced it was seen that the liquid is not absorbed homogeneously throughout the polymer sample and a more intense region is seen at the front of the image suggesting a solvent front. Commercial superabsorbent polymers are usually coated to enhance their absorptive properties. Experiments were carried out using a sodium ion-selective electrode to try and determine whether or not this coating provided the polymer with an osmotic ion-exclusion membrane. The sodium ion-selective electrode allowed differences in [Na+] before and after the addition of polymer to a solution of NaCl to be detected, and consequently allowed the presence of an osmotic ion-exclusion membrane to be determined.

This study is concerned with the synthesis of conjugated polyheterocycles with potential metal binding sites for applications in sensors, catalysis and electronics. The first synthetic approach to polyheterocycles was based on the interfacial polycondensation of a dihydrazide derivative of pyridine with a diacid chloride to produce a precursor polymer. It was shown, however, the starting materials could not be easily prepared in high yield. Model studies confirmed the feasibility of the route but these studies also suggested that the precursor polymers were unlikely to be very soluble. The second precursor route explored began with the preparation of 2,6-diethynylpyridine. The intermolecular Glaser coupling of the ethyne groups afforded the precursor polymer, poly((2,6'-pyridyl)but-l,3-diyne), as a black powder which was insufficiently soluble to allow conversion to the poly heterocycles. A series of dimers and trimers containing various combinations of 2-furyl, 2-thienyl and 2-pyridyl moieties were prepared using two different coupling procedures that yielded compounds with the required 2,2'-heteroatom arrangement as required for metal binding. Some of these monomers were electropolymerised and the metal binding properties of these polymers was investigated by cychc voltammetry. In particular, the two trimers: 2,5-di-(2-thienyl) pyridine; and 2,6-di-(2-thienyl) pyridine showed potential metal coordination despite their hydrophobic nature and impermeability towards metal complexes. Evidence was presented to suggest that these polymers are protonated during the electropolymerisation reaction. X-ray analysis of the 2,5-di-(2-thienyl) pyridine showed that only the 2,2'-linked thiophene was coplanar with the pyridine due to a charge transfer interaction. This interaction insures that S and N atoms have a planar syn arrangement conducive to metal binding. Several oligothiophenes were prepared to investigate methods for enhancing the solubility of polyheterocycles. The knowledge gained from these investigations was used to prepare a series of regiochemically well-defined poly((3-alkyl)thiophenes). The regularity of these polymers was confirmed by NMR analysis. Related monomers were prepared containing the necessary solubilising alkyl groups as well as phenyl groups designed to act as acceptor ligands for the low-valent transition metals such as ruthenium(II). The electrochemistry of these novel thiophene monomers is reported.

The aim of the work carried out for this thesis was to explore way to synthesise and characterise π-conjugated ferrocene containing polymers by using a condensation polymerization technique. Three types of such compounds were investigated: namely polyquinoxalines (pox)s, polyimines (PJ)s and polyketones (PK)s. The work was started by carrying out the same reactions on small molecules, in order to understand the reaction pathway and to establish the reaction conditions and to obtain the benchmark characterisation data. Initially monofunctional ferrocene derivatives were prepared and condensed with mono- and bi-functional organic molecules, and bifunctional ferrocene derivatives were synthesised and condensed with mono functional organic molecules, to yield the small molecular condensation products. When the reaction conditions had been optimised the same reactions were extended to bifunctional ferrocene derivatives and bifunctional organic entities to obtain the co-polymers. After citing the relevant references in chapter one, the synthesis of mono- and bi-functional ferrocene containing diketones (FcCOCOK) by the oxidation of the synthesised mono-ketones is described in chapter 2 and their condensation with unsubstituted and substituted organic di- and tetra-amines to produce ferrocene containing mono-, bis - and poly-quinoxalines is described in chapter 3. The crystal structures of some of the compounds are also determined as definitive proof of characterisation. The attempted oxidation of ferrocenyl monoketones (FcCH2COR) to diketones by using selenium dioxide produced the coupled, dimeric, products (FcCHCOR)2. Electrochemical studies of the synthesised quinoxalines were also carried out. In chapter 4 are described the condensation of ferrocene aldehyde (FcCHO) and dialdehyde [(Fcd(CH0)2] with aromatic amines to yield ferrocene containing mono-, bis-and poly-imines. Chapter 5 deals with the synthesis and characterisation of ferrocene containing mono-, bis- and poly ketones synthesised by Friedel Crafts acytation reactions. The molecular weights of the synthesised ferrocene-containing polymers are also estimated with the help of hi NMR spectra.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2007. / Additional advisors: Houston Boyd, Tracy Hamilton, Christopher Lawson, Charles Watkins. Description based on contents viewed Feb. 8, 2008; title from title screen. Includes bibliographical references.

No description available.

Thesis (Ph.D.)--Baylor University, 2005. / Includes bibliographical references (p. 273-283).

Thesis (Ph. D.)--University of Rhode Island, 2000. / Typescript. Includes bibliographical references (leaves 123-138).

Thesis (Ph. D.)--McMaster University (Canada), 1989. / Source: Dissertation Abstracts International, Volume: 62-13, Section: A, page: 0000.