Recyclable non-isocyanate polyurethanes containing a dynamic covalent network derived from epoxy soybean oil and CO2

Abstract

As one of the important reasons for the greenhouse effect, CO₂ can be effectively fixed by reacting with epoxides to synthesize the raw material cyclic carbonate of non-isocyanate polyurethanes (NIPUs). Thus, the environmental problems caused by CO₂ and toxic isocyanates can be alleviated. Hence, we reported a strategy to use CO₂ by preparing bio-based NIPUs using cyclic carbonated soybean oil with amines. The effect of the structure of the NIPUs on their mechanical properties, thermal properties, and dynamic thermomechanical properties was explored. More importantly, stress relaxation was performed to confirm the bond exchange behavior of hydroxyl with carbamate. The mechanical properties of NIPUs after physical hot pressing and chemical degradation recycling can be restored to at least 85% of their original values, indicating excellent reprocessing. The shape of the NIPUs is almost completely recovered, confirming the attractive shape memory. This work reveals an effective method for preparing bio-based NIPUs using the cyclic carbonate obtained by fixing CO₂ with epoxy soybean oil; as expected, they exhibit interesting reprocessing and shape memory performance.