Cyclic carbonate opening with simultaneous trapping of hydroxyl groups: A novel strategy for NIPU synthesis

Aminolysis of cyclic carbonates is one of the most promising routes for synthesizing non-isocyanate polyurethanes (NIPUs), yielding polyhydroxyurethanes (PHU). However, extensive hydrogen bonding from vicinal hydroxyl groups has been reported to hinder polymerization, limiting achievable high molar mass PHUs. In this study, we investigated the role of hydrogen bonding by designing a multifunctional monomer that suppress hydroxyl groups via silane chemistry. This approach, validated in a model system, was applied to polymerization and yielded a functionalized polymer with properties markedly different from the control polymer. Molecular weight comparison was performed using size exclusion chromatography (SEC), and thermal properties were subsequently evaluated. This manuscript highlights the negative effect of hydrogen bonding during the cyclocarbonate amine addition on NIPHU final molecular weight. This is directly highlighted by using designed bicyclocarbonates containing silane groups that will trap the formed hydroxyl groups by cyclosiloxane formation and lead to a novel class of NIPU. This last exhibit better thermal properties and higher molecular weight compared to their NIPHU homologs. This novel strategy opens to a new class of NIPU obtained via the cyclocabonate amine addition and confirm that of OH groups absence in NIPU structures positively impact Mw.