Preparation of Polyurethane-Urea Elastomers Using Low Molecular Weight Aliphatic Diamines Enabled by Reversible CO2 Chemistry

The use of low molecular weight (LMw) aliphatic diamines for the synthesis of polyurethane-urea elastomers (PUUEs) is an effective method for introducing abundant, strong hydrogen bonds with the aim of improving the thermal and mechanical properties of PUUEs. However, the reaction between isocyanates and LMw aliphatic diamines is too rapid to produce PUUEs. In this study, PUUEs incorporating LMw aliphatic diamines as chain extenders are prepared via the reversible reaction of CO 2 with diamines. The phase separation, thermal properties, and thermomechanical and mechanical properties of polyurethane materials are investigated as the chain extender changed from diol to diamine. Replacing the diol chain extenders with diamine results in the formation of more abundant and stronger hydrogen bonds in PUUEs, which enables the assembly of long range ordered structures and improved microphase separation. The tensile strengths of PUUEs, from 8.4 to 13 MPa, are much higher than their corresponding polyurethanes, owing to the physical crosslinks formed by the more and stronger hydrogen bonds in the PUUEs.