Konstitutionsisomerie in Polykondensaten. Teil VI. Synthese und Eigenschaften von voellig geordneten und ungeordneten Bipolymaiden aus cis-2,6-Dimethylpiperazin und 1,2,5-Thiadiazol-3,4-dicarbonyl-dichlorid

Article abstract of DOI:10.1002/hlca.19900730409

The synthesis of constitutionally perfectly regular and random alternating copolyamides from the 'symmetric' monomer 1,2,5-thiadiazol-3,5-dicarbonyl dichloride (4) and the 'non-symmetric' monomer cis-2,6-dimethylpiperazine (7) by solution and interfacial polycondensation methods is described.Their constitutional regularities (s values) were determined by high-resolution 13C-NMR spectroscopy in CDCl3 solutions.Ordered and random copolyamides were amorphous with T_g values of ca. 200 deg C.However, the regular head/tail and the random copolyamides with low molecular weights could be partially crystallized by annealing and showed large differences in their melting points (54 deg C).Beside other physical properties, the membrane properties of the copolyamides were carefully investigated.In H2O desalination by reverse osmosis, no difference in salt rejections and permeabilities between constitutionally regular and random copolyamides were found (within experimental error).In contrast, the regular head/head/tail/tail- and head/tail-type copolyamides showed considerably larger seperation factors in the gas seperation (methane/hydrogen) than the random ones.