Carbon dioxide-based poly(hydroxyurethane-urea) elastomers: Synthesis, microphase structure, and properties

Compared with isocyanate-based polyurethanes (PUs), poly(hydroxyurethane)s (PHUs) are more likely to form phase mixing structure, inducing poor elastic properties. To avoid this, stronger interaction between hard segments is required. Herein, carbon dioxide-based poly(hydroxyurethane-urea)s (PHUUs) with different hard segment contents were prepared through polyaddition reaction using 5-membered dicyclic carbonate (BADC) as hard segment, poly(propylene glycol) bis(2-aminopropyl ether) (D2000) as soft segment, and amino-terminal polyurea oligomer (HMDA*) chain extender, and several PHUs were prepared by using hexamethylenediamine (HMDA) chain extender or without using chain extender as controls. The interaction between hard segments were strengthened with the introduce of chain extender. Compared with PHUs, PHUUs with HMDA* chain extender were more inclined to form significant microphase separation. For PHUUs, the hard segment T g appeared at around 60°C when hard segment content reached 40 wt%, and the interdomain spacings were in the range of around 14–23 nm with 40–50 wt% hard segment content. In addition, PHUUs exhibited better solvents resistance and mechanical properties than PHUs with the same hard segment content. PHUUs with certain hard segment content showed good elastic recovery, with a residual strain less than 2% after 10 cycles, which comparable with conventional isocyanate-based PUs.