Organic-Inorganic Polyureas with POSS Cages in the Main Chains via Polycondensation of Diamines with Carbon Dioxide

Linear organic-inorganic polyureas (PUreas) with polyhedral oligomeric silsesquioxane (POSS) cages in the main chains were synthesized via polycondensation of diamines with carbon dioxide (CO2). First, 3,13-dianilino double decker silsesquioxane (denoted 3,13-dianilino DDSQ) was synthesized. An alpha, omega-diamino-terminated poly(propylene oxide) as well as the POSS diamine was exploited for polycondensation with CO2; PUrea and PUrea-DDSQ with sufficiently high molecular weights were obtained with various contents of POSS. The morphological investigation shows that the linear PUreas with POSS cages in the main chains were microphase-separated; the POSS cages were aggregated into spherical microdomains with the size of 50-120 nm in diameter. Owing to the introduction of POSS cages, PUrea was transformed from a viscous liquid into elastic solids in the ranges of composition investigated. At room temperature, linear organic-inorganic PUreas behaved as cross-linked elastomers. This behavior is ascribed to the generation of physical cross-linking with POSS microdomains as the cross-linking sites. In addition, the organic-inorganic PUreas displayed self-healing properties via the dynamic exchange of multiple hydrogen bonds. It was found that the self-healing properties were significantly affected by the content of 3,13-dianilino DDSQ.

Automated summary

Linear organic-inorganic polyureas (PUreas) with polyhedral oligomeric silsesquioxane (POSS) cages in the main chains were synthesized via polycondensation of diamines with carbon dioxide (CO2). The PUreas exhibited microphase separation with aggregated POSS cages forming spherical microdomains. The introduction of POSS transformed PUrea from a liquid to an elastic solid, behaving as a cross-linked elastomer at room temperature. Additionally, the PUreas displayed self-healing properties through the dynamic exchange of multiple hydrogen bonds.