Date of Completion

January 1984


Chemistry, Polymer




Fluorescent probes have been used in synthetic polymers to study molecular orientation, motion, and structure; however, most of the research has been conducted on polymer melts and solutions. Of the few studies made with solid polymers and polymer blends, none has investigated phase-segregated systems. This research examined the fluorescence behavior of polyurethanes, which are phase-segregated, elastomeric polymers.^ Two fluorescent dyes, 2-diphenylacetyl-1,3-indanedione-1-p-dimethylaminobenzaldazine (3) and its functionalized analogue 2-diphenylacetyl-1,3-indanedione-1-p-bis((beta)-hydroxyethyl)aminobenzaldazine (7), were used to study the chemical, physical, and morphological properties of polyurethane block copolymers. The fluorescent molecules were either dispersed (dye 3) within the polyurethane matrix or covalently bonded (dye 7) to the polyurethane.^ The first phase of this research involved the synthesis of 3, according to the procedure of Braun and Mosher, and its functionalized derivative, 7, a novel compound, heretofore not reported in the scientific literature. The second phase of the research involved the incorporation of these dyes into amorphous polyurethane matrices. An amorphous polymer was selected because of its inherent transparent nature.^ These dyes permitted the successful use of fluorescence spectroscopy in following phenomena resulting from decreases in free volume. This technique can be used to detect thermal transitions by monitoring changes in fluorescence intensity. The nature of the transition can also be identified. The course of the polymerization reaction and the process of physical aging were monitored using the same technique. Data obtained from fluorescence measurements strongly correlated with those obtained by conventional techniques. Compatibility between the hard and soft segment domains could also be evaluated because fluorescence is highly sensitive to the local environment. A technique capable of analyzing interdomain compatibility in phase-segregated polyurethanes has not been previously reported. ^