Porous Non‐Isocyanate Polyurethane by Stepwise Polymerization‐Induced Micron Phase Separation between Evolving Polymer Network and Solvent

Abstract Porous polyurethane accounts for half the global polymer foam market. However, the synthesis of polyurethanes (PUs) heavily relies on the use of highly toxic isocyanates, raising significant health and environmental concerns. Non‐isocyanate polyurethane (NIPU), as a safer alternative, has emerged via the polymerization of multifunctional cyclic carbonates and amines. Nevertheless, NIPUs are seldom explored as porous materials compared to conventional PUs primarily because their synthesis is based on isocyanate‐free cyclic carbonate‐amine chemistry, making it challenging to replicate the foaming process of traditional PUs, which relies on in situ CO ₂ production through isocyanate hydrolysis. In this study, the highly efficient preparation of porous NIPU through step‐growth polymerization‐induced micron phase separation between the evolving polymer network and the solvent is reported. A series of NIPUs with unconventional porous structures are facilely prepared via a convenient one‐pot method in the absence of catalysts and any in situ generated or additional blowing agents at room temperature and atmospheric pressure. Furthermore, this strategy can be successfully extended to the production of flexible NIPU/cellulose fabric hybrid porous materials. This strategy provides a facile approach to accessing porous NIPU and NIPU hybrid materials, which is beneficial to the wide applications of NIPUs in different fields.