Polyurethane elastomers through multi-hydrogen-bonded association of dendritic structures

A series of hydrogen bonding-rich polyurea/malonamide dendrons have been utilized as building blocks for the synthesis of novel dendritic polyurethane elastomers. Based on the resulting microstructure of soft segments reinforced by the rigid dendritic domains, the hydrogen bonding enforced phase separation of segmented polyurethanes was explored. DSC and FT-IR results indicate that a certain degree of phase separation between dendritic and poly(tetramethylene oxide) (PTMO) domains. The domain size of phase separation are less than 100 nm based on the results obtained from the atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS). The analysis of tensile measurements indicates that the incorporation of various contents of different dendrons as the hard segments allows these polymers to exhibit drastically different mechanical properties. Furthermore, low complex viscosity is observed at medium temperatures (above 130 °C) via the rheological analysis. With good mechanical properties at room temperature and low melt viscosity at medium temperatures, these thermoplastic elastomeric polyurethanes are suitable for applying in hot-melt process.