Properties and morphology of segmented copoly(ether urea)s with uniform hard segments

Block copoly(ether urea)s with uniform hard blocks consisting of two urea groups possess appealing elastomeric properties. The crystal structure of a model bisurea illustrates the formation of long stacks of hydrogen-bonded urea groups. Thermal anal. of these polymers demonstrates the reversible melting of the hard blocks, causing the material to flow. The low glass transition temp. ensures excellent low-temp. flexibility. The morphol. of the material consists of long stacks of assocd. hard blocks embedded in the soft phase. Elongation of the materials demonstrates their highly elastic behavior, with a strain at break ranging from 1000 to 2100%. During tensile testing, irreversible deformation and reorganization of the hard blocks occur, resulting in a significant amt. of tensile set. These well-defined polymers proved to be superior compared to a less-defined analog having a polydisperse hard block.