Non-isocyanate polyurethanes derived from carbonated soybean oil: Synthesis, characterization and comparison with traditional vegetable oil-based polyurethanes

The polyaddition between carbonated vegetable oils and diamines to form non-isocyanate polyurethanes (NIPUs) has been highlighted as a safer and more sustainable alternative to traditional polyurethanes (PUs) synthesis. Although NIPUs exhibit a broad range of properties, research so far has been more focused on exploring their synthetic routes rather than on the evaluation of their performance versus traditional PUs in a given application making complicate to determine if NIPUs can be considered an efficient and plausible, in terms of performance, alternative to their fossil fuel-bases PUs counterparts. In this work, a series of carbonate soybean oil-based NIPUs (CSBO-NIPUs) have been prepared by polyaddition of CSBO with three different diamines (MBCHA, DAO and Primaine1074) yielding CSBO-NIPUs with bio-base content well above 73 %. The obtained CBSO-NIPUs exhibited glass transition temperatures between −29 °C and 21 °C, decomposition temperatures in the range of 261 °C to 304 °C, excellent impact resistance (>100 kg/cm²), soft pencil hardness (6B) and a polymeric network with up to 74 % cross-linking degree. The performance of the prepared CSBO-NIPUs was compared with PUs (found in the scientific literature) synthesized from vegetable oil-based polyols and diisocyanates by the traditional synthetic route. The comparison revealed that CSBO-NIPUs show comparable or superior potential than the vegetable oil-based traditional PUs in terms of thermal stability, impact resistance and cross-linking degree. In conclusion, the polyaddition process sustainability in line with Green Chemistry principles along with CBSO-NIPUs excellent thermal and impact resistance place these materials in a promising position a viable alternative to traditional PUs in the near future.