Organic and inorganic polyamides: Studies of their synthesis and reactivity.

摘要

This thesis research examines the chemistry of two polymer families, aromatic polyamides and polyphosphazanes. These compounds were used to model chain extension and a variety of oxidation reactions. The thesis work is divided into four distinct efforts carried out in order to understand selected aspects of the chemistry of polyphosphazanes and aromatic polyamides.; Linear phosphazanes were used to model the stereochemistry of phosphazane polymer chain extension reactions. Tri- and dichlorophosphazanes that are similar to logical intermediates in the condensation polymerization of skeletally stabilized polyphosphazanes were allowed to react with amines of varying steric bulk. Increasing stereoselectivity was observed with increasing steric bulk of the incoming amine.; Sulfur oxidation of linear phosphazanes was studied in order to gain insight into the mechanism of regioselectivity in phosphorus-site oxidation. Di- and triphosphazane oxidation was monitored by 31P NMR spectral analysis. Oxidation reactions were analyzed using a computer program to obtain relative rate constants for the pseudo first-order reactions. A similar deactivation occurs in the oxidation of diphosphazanes. It is proposed that the mechanism of deactivation is steric; oxidation of a phosphorus atom leads to changes in conformational populations that result in deactivation of the adjacent phosphorus-sites.; Oxidations of aromatic amides were studied as models of the chlorine oxidation reactions that are observed in aromatic polyamide reverse osmosis (RO) membrane degradation. An attempt has been made to correlate the available chlorine concentration, pH and exposure time to observed chemical changes in the model compounds. From these reactivity trends, insights are obtained into the mechanism of RO membrane performance loss upon chlorine exposure.; There is currently no established correlation between the chemical changes that occur in a polyamide barrier layer as a result of aqueous chlorine exposure and subsequent physical changes in the film. A novel analytical technique, pendant drop mechanical analysis (PDMA), was used to detect changes in the water transport and mechanical properties of the polyamide barrier in a situation where it is free of the microporus support. (Abstract shortened by UMI.)