High Molar Mass Non‐Isocyanate Polyurethanes by Transurethanization of Diols with Isophorone‐Based Bismethylcarbamate

The synthesis of thermoplastic polyurethanes (TPU) has been associated with sustainability issues, prompting the development of alternative synthesis routes avoiding the use of isocyanates. One approach deals with non-isocyanate polyurethanes (NIPUs), which are obtained by transurethanization of bismethylcarbamates and diols. However, this reaction exhibits reactivity penalties in comparison to the polyaddition of isocyanates with diols, and the optimization of the reaction conditions is required to achieve high molar mass polyurethanes. In this report, a series of NIPUs is synthesized via transurethanization using methyl((5-((methoxycarbonyl) amino)-1,3,3-trimethylcyclohexyl) methyl)carbamate and various diols. The reaction is first optimized using 1,12-dodecanediol and different catalysts are investigated. High molar mass polyurethanes (Mn up to 30 kDa) are achieved using potassium carbonate (K2CO3) as a catalyst, confirming that the polytransurethanization route is a good alternative to the isocyanate route. The optimized conditions are then applied to different diols. The thermal properties of the resulting polymers are analyzed by differential scanning calorimetry (DSC), in which all investigated NIPUs exhibited an amorphous character with a glass transition temperature (Tg) varying from −68 to 128 °C.