Morphology of block copolyurethanes: V. The effect of -CH2CH2- vs -CH2- spacers between aromatic rings

Copolyether-urethane-ureas based on 1,2-ethylene bis(4-phenylisocyanate), polypropylene glycol and ethylene diamine were synthesized by both the standard two-step and a multi-step procedure and their properties compared with analogous copolyurethanes based on methylene bis(4-phenylisocyanate). The infrared and dynamic mechanical properties indicate differences in the packing structure of the hard domains between these two copolymer systems. The infrared data suggest that the introduction of a -CH2CH2- spacer between the two aromatic rings of the diisocyanate results in a coplanar packing in the hard domains for these copolyurethanes.