Preparation and characterization of deuterized polymers for neutron scattering studies

Some perdeuterized, partially deuterized, and some analogous undeuterized, low-molecular and macromolecular substances were synthesized and characterized. Oligo(ethylene oxide) with methyl ether or methyl ether/hydroxyl end group can easily be prepared in the range of molecular weight between 103 and 104. Linear and cyclic n-alkanes up to n=384 or 288, respectively, and the corresponding periodically partially deuterized alkanes were obtained on a preparative scalle from poly-, diacetylenes; the corresponding high polymer, partially deuterized polyethylene, is obtainable by deuteration of polyocteneamer. As to segmented polyurethane elastomers, partially and perdeuterized elastomers with monodisperse hard segments were obtained on the basis of 4,4'-diphenyl methane-diisocyanate/butanediol and poly(oxytetramethylene) soft segment, applying novel principles of synthesis. The significant findings and results obtained in connection with the characterization of specimens and by means of the neutron scattering experiments are the following: in n-alkanes, the thermal pretreatment has a determining effect on chain folding, which occurs only above a chain length of 120 CH2 units; with polyurethanes, hard segments show little, if any, tendency to allow chain folding, and at temperatures above their melting temperature re-urethanization reactions set in. (orig.) With 7 refs., 2 figs