Abstract

The reaction of trimethylolpropane (TMP) and diphenyl carbonate gives three types of TMP-based six-membered cyclic carbonates (TMPCs) via phosgene-free route. TMPC having one hydroxyl group (TMPC-OH) reacted with terephthaloyl chloride or trimesoyl chloride to give bifunctional (Ph-TMPC₂) or trifunctional cyclic carbonate monomers (Ph-TMPC₃), respectively. The ring-opening polyaddition of Ph-TMPC₂ and conventional diamines efficiently proceeded without the cleavage of ester bonds to afford linear polyhydroxyurethanes (PHUs) with well-controlled molecular weights and polydispersities via isocyanate-free route. Moreover, the polyaddition of Ph-TMPC₂ and diamine at TMPC₂/diamine feed ratio of 1.1 afforded PHUs having cyclic carbonate terminals, the hydroxyl side chains of which were easily reacted with acetic anhydride to give acetylated PHUs with cyclic carbonate terminals. On the other hand, the polyaddition at Ph-TMPC₂/diamine feed ratio of 0.91 gave PHUs with amine terminals. The copolymerization of Ph-TMPC₂, Ph-TMPC₃ and diamine gives PHUs comprising covalently-bridged networked structures. After DMF solutions of Ph-TMPC₂, Ph-TMPC₃ and diamines were simply kept at 60 °C overnight, networked PHU films with well transparency were successfully fabricated. The PHU films prepared at different diamines showed similar transparency and thermal stability, while the mechanical properties were significantly affected by the methylene spacers of diamines.

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