Moisture Curable Hybrid Polyhydroxyurethanes from Sugar-Derived Dicarbonates

A new set of polyhydroxyurethanes (PHUs) is synthesized from bio-based sorbitol bicarbonate (SBC) and mannitol bicarbonate (MBC). The synthesized dicarbonates are polymerized with two long chain diamines, telelechelic amine terminated poly(propylene glycol) (PPG), and poly(dimethylsiloxane) (PDMS). Despite the high melting points of SBC and MBC, PHU prepolymers are prepared in bulk at moderate temperatures of 60–100 °C. The structural and thermal properties of the resulting PHUs are qualitatively and quantitatively characterized in order to evaluate them as potential sealants and adhesives, and they are end-capped with moisture curing agents and left to cure at ambient conditions (22 °C and 20–30% humidity) with the curing processes monitored rheologically. The chemical stability of the novel partially sustainable hybrid PHUs (HPHUs) in pure water is investigated to check the viability of applying them outdoors. Only SBC or MBC-PDMS HPHUs are found to be hydrophobic with water contact angles of 105° and 109°, respectively, but they are brittle. Small and wide-angle X-ray scattering of these water-resistant films show that they are potentially composed of three different phases due to microphase separation: the PDMS matrix, a hard segments phase, and a third phase mixing the PDMS diamine end-segments and some dissolved hard segments.