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Thesis (Ph. D.)--Michigan State University. Dept. of Chemistry, 2006. / Title from PDF t.p. (viewed on June 19, 2009) Includes bibliographical references (p. 187-197). Also issued in print.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 276-287). Also available via the Internet.

Poly(ethylene terephthalate) (PET) is an important commercial polyester and widely used as fibers, packagings, containers and engineering materials. It is believed that the incorporation of a low level of ionic groups into PETs dramatically improves the mechanical performance and compatibility with other substrates. However, polymers containing ionic groups always exhibit complicated behavior due to the presence of ionic aggregates in the organic matrix, and this thesis investigates the effect of backbone architectures on the properties of PET ionomers in detail. Three series of random and telechelic PET ionomers with equivalent molecular weights and ionic contents were synthesized using conventional melt polymerization. Solid state sodium NMR spectroscopy and melt rheological analysis demonstrated that the stability of ionic aggregates of telechelic ionomers decreased dramatically with an increase in temperature. A slightly branched structure resulted in high molecular weight ionomers bearing more than two ionic end groups. However, when the level of the branching reagent was lower than 3 mol%, the ionomers with flexible backbone (poly (ethylene terephthalate-co-ethylene isophthalate)) tended to form a high fraction of intramolecular aggregates at high temperatures. When the level of branching agent was higher than 3 mol%, the compact structures led to strong intermolecular aggregates. PEG endcapped PET and PET random ionomers were synthesized to investigate the effect of PEG end groups on the morphology and rheology of PET and PET ionomers. A small fraction of incorporated PEG end groups increased PET crystallization rate dramatically. Moreover, the PEG endgroups tended to aggregate on the surface of PET to result in a PEG rich layer, which improved the biocompatibility and decreased protein adhesion. The PEG end groups also plasticed the ionic clusters of PET ionomers to decrease melt viscosity, and resulted in a water soluble polyester. Hyperbranched polymers contain a well-defined plurality of peripheral functionalities. These functionalities subsequently serve as sites for further chemical modification or as templates for noncovalent intermolecular association. In most cases, hyperbranched polymers are prepared using a one-step polymerization process involving ABn monomers. A novel AB2 monomer, 4-(fluorophenyl)-4',4"-(bishydroxyphenyl) phosphine oxide, was synthesized. The monomer was successfully polymerized to a modest molecular weight with various catalysts, including K₂CO₃ and Cs₂CO₃/Mg(OH)₂. Moreover, an efficient approach to hyperbranched polyarylates via the polymerization of A2 and B3 monomers without gelation was also developed. A dilute bisphenol A (A2) solution was added slowly to a dilute 1,3,5-benzenetricarbonyl trichloride (B3) solution at 25 °C to prepare hyperbranched polyarylates in the absence of gelation. / Ph. D.

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Oligomers of hard and soft segments of unsaturated polyesters were synthesized in two steps. For the hard segment, isophthalic acid was reacted with 1,2-propanediol first, then maleic anhydride was added for further esterification. For the soft segment, diethylene glycol was used to replace 1,2-propanediol. In the previous study, the excess amount of glycol was 20% in weight. In this study, glycol was 10 and 5 wt% in excess, respectively. Decreasing the excess amount of glycol from 20 to 5 wt%, the number average molecular weight of both hard and soft segments increased about 30-40% from 1000 g/mol, and the degree of isomerization of maleic acid changed from 40.5 to 57.3% for the oligomers of the soft segment. The hard and soft segments synthesized in this study were blended in weight ratios from 0 to 100 % in an interval of 20 %, and then cured with styrene for further mechanical testing. The micro-tensile strength of cured soft and hard segments increased 1.3 and 8 times, respectively, in this study compared with that of specimens prepared under the condition of 20 wt% in excess of glycol. Therefore, the criteria of inhibitors can also be achieved by varying the excess amount of glycols. To evaluate the nitroglycerine migration and the erosion rate, only two (60% hard segment and 40% soft segment) of the formulas which passed the criteria of mechanical properties were investigated by replacing lithophone with magnesium hydroxide. In the case of 10 wt% in excess of glycol, the migration of nitroglycerine at infinite time (M

Reproduction de : Thèse de doctorat : Chimie des Matériaux : Reims : 2004. / Titre provenant de l'écran titre. Bibliogr. p. 201-212.