Polyvinyl alcohol (PVA) has been widely used in fibre and paper industries. Due to its excellent biocompatibility, biodegradability, water solubility and gas permeability, PVA has recently attracted enormous interest in special applications such as biochemical, biomedical and environmental-friendly packaging materials. However, its poor thermal aging resistance, miserable solvent resistance and insufficient mechanical property have greatly restricted PVA’s further applications. / To overcome these drawbacks of PVA, in the present study, silica nanoparticles are introduced into PVA matrix to prepare a polyvinyl alcohol/silica (PVA/SiO²) nanocomposite by incorporating self-assembly and solution compounding techniques. Different from other conventional processes for preparing nanocomposites such as sol-gel process, intercalation and physical blending, the process developed in this study is simple, universal, low cost, yet effective, and easy to be scaled up for industrial exploitation. / Thesis (PhD)--University of South Australia, 2006.

Doctor of Philosophy (PhD) / Oligomeric surfactants, sometimes referred to as gemini surfactants, consist of two or more amphiphilic ‘monomer’ units linked together by spacer groups. The chemical identity of the spacer group is unconstrained, and it joins the individual units at or near the hydrophilic headgroups. Oligomeric surfactants display a range of interesting properties, including very low critical micelle concentrations, high surface activity and unusual rheology and self-assembly. Consequently they have many potential applications, both scientific and industrial. Until now, their use has been limited by the cost of their synthesis, which in some cases involve long and difficult procedures. This project developed from the idea that a synthesis based on polymerization could prove a useful and versatile method for producing these surfactants. The chemical starting point for this project was a series of polymerizable surfactants (‘surfmers’), upon which polymerization was performed. Two families of surfmers were investigated, both cationic and based on methacrylate and vinylpyridinium moieties respectively. The physical behaviour of these surfactants – a number of which are new – was investigated using standard techniques; these included the determination of the critical micelle concentration, characterization of phase behaviour, neutron scattering and surface adsorption. In producing oligomers, the initial focus was on free-radical polymerization, with control of molecular weight to be achieved by chain-transfer techniques. Due largely to analysis problems, this work proved unsuccessful. In its place a new reaction, not based on conventional polymerization methods, has been developed. The vinylpyridinium surfmers mentioned above readily undergo addition across the double bond to produce alkyl ring substituents. Under basic conditions, these alkylpyridiniums undergo an elimination/addition reaction in which they link together to form oligomers. This reaction can be started or stopped by raising or lowering the pH of the reaction solution, and has been performed in both organic and aqueous solutions. It is referred to in this thesis as LELA(Linkage by ELimination/Addition). The LELA reaction was used to produce mixtures of oligomers, the phase behaviour and surface adsorption of which were examined. Small-angle neutron scattering was used to monitor the reaction in real time and identify changes in self-assembly as the average oligomer length increased. Progress was also made towards a chromatographic protocol that would allow mixtures to be separated into their components and the pure oligomers to be studied. Finally, some of the compounds studied display interesting pH-dependent chromophoric properties which were also found to occur with other simple alkylpyridinium species. They are tentatively ascribed to inter- and intramolecular charge-transfer complexes, and evidence towards this conclusion was collected and is presented along with relevant calculations.

[Truncated abstract] An efficient synthesis of the p-phosphonic acid calix[n]arenes, (n = 4, 5, 6 and 8) in five steps and excellent yield has been developed. This includes the key use of an acetyl protecting group, which is straightforward to introduce and remove using acetic anhydride and potassium hydroxide respectively. The synthesized p-phosphonic acid calixarenes are water-soluble and the hydrogen bonding prowess of the acidic groups dominates its selfassembly processes. For p-phosphonic acid calix[4]arene these include the formation of nano-rafts in the gas phase (≤ 20 molecules) and nano-particles (3.0(3) and 20.0(2) nm) of the calixarene in water using spinning disc processing stabilized by acetonitrile. The larger p-phosphonic acid calix[5,6,8]arenes also show nano-raft formation in both solution and the gas phase. An extensive study of the supramolecular chemistry of calix[5]arene has also been undertaken to better understand its rich structural diversity. This includes the formation of chloromethane inclusion complexes of p-tert-butyl-calix[5]arene and p-H-calix[5]arene with dichloromethane, p-phenyl-calix[5]arene with chloroform and their potential application as gas storage materials. Along with these three investigated inclusion complexes are two sublimates of p-H-calix[5]arene (α and β) with only the β-polymorph active for sorption of carbon dioxide at room temperature and 1 atm. The α-polymorph adopts an inverted cone conformation and forms helical stacks in the extended structure whereas the β-polymorph adopts the usual cone conformation and packs in both 'self included' and 'back-to-back' helical arrangements. ... Complementary to this study involved the p-H-calix[5]arene inclusion complexes with fluoro-, chloro-, bromo- and iodobenzene. All but the iodobenzene complexes are isostructural forming columnar arrays in the extended packing comprised of 'tri-calix[5]arene' segments. Iodobenzene is too large to form the respective 'tri-calix[5]arene' segments and instead forms sheets in the extended packing. To better understand the type and nature of the intermolecular interactions present within the supermolecules and extended structures a detailed Hirshfeld surface analysis was performed. A detailed Hirshfeld surface analysis was also performed on O-octadecyl-calix[6]arene, which crystallizes in the inverted double cone conformation. Three alkyl chains on either side interplay to form one side of hexagon in an hexagonal close packed array of interdigitated alkyl chains. This was the first Hirshfeld surface analysis performed at variable temperatures and enhanced the description of such a large supramolecular system. The related compound O-octadecyl-calix[4]arene was found to crystallize from toluene or benzene as supramolecular bilayers, 32.2(4) and 32.7(2) Å thick respectively. The calixarenes adopt the cone conformation and the alkyl chains interplay to form a continuous hexagonal motif similar to that seen for O-octadecyl-calix[6]arene. The formation of stable bilayers using octadecyl chains leads to the possibility of inserting long chain calixarenes with suitable functionalization into biological membranes. Such functionalization could include upper rim phosphorylation as seen for the p-phosphonic acid calixarenes to produce phospholipid mimics.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (leaves 111-116).

Thesis (Ph. D.)--State University of New York at Binghamton, Dept. of Chemistry, 2007. / Includes bibliographical references.

Thesis (Ph. D.)--University of Delaware, 2007. / Principal faculty advisor: Darrin J. Pochan, Dept. of Materials Science & Engineering. Includes bibliographical references.

Thesis (Ph.D.)--University of Delaware, 2007. / Principal faculty advisor: Joel P. Schneider, Dept. of Chemistry & Biochemistry. Includes bibliographical references.

Thesis (doctoral)--University of Helsinki, 2007. / Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--University of Oregon, 2007. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 158-174). Also available for download via the World Wide Web; free to University of Oregon users.