Non-isocyanate polyurethanes from renewable bio-polyols via dimethyl carbonate-mediated urethanisation: Synthesis and properties

The growing need for safer and more sustainable polyurethane (PUR) has driven the development of non-isocyanate polyurethane (NIPU) systems that eliminate toxic isocyanates while increasing the use of renewable resources. Among the most promising emerging synthesis strategies is the dimethyl carbonate (DMC)-mediated urethanisation, which enables the direct formation of urethane linkages under relatively mild conditions without the use of either isocyanates or cyclic carbonates. This review critically discusses advances in NIPU synthesis via DMC-mediated urethanisation, with a special focus on its integration into renewable polyols derived from biomass resources. Direct urethane synthesis routes using DMC, including transurethanisation and step-growth polyaddition, are comprehensively reviewed, with particular emphasis on polymer architecture and network formation. Additionally, the molecular structures, curing behavior, thermal stability, hydrolytic resistance, and mechanical properties of NIPU derived from various bio-polyols are critically reviewed to identify the key factors governing material performance. The roles of catalysts, crosslinkers, and polymer modification in DMC-based NIPU are also discussed. These insights provide important guidance for the development of DMC-based NIPU as commercially viable high-performance materials, highlighting future research priorities. Therefore, this paper builds a valuable knowledge base on the utilisation of DMC and bio-polyols in NIPU synthesis, which could serve as a vanguard for future research directions in this fascinating field.