Self-Blowing Non-isocyanate Polyurethane Foams from Cyclic Carbonate Linseed Oil

Non-isocyanate polyurethane (NIPU) foams prepared from renewable resources have attracted much attention as benign alternatives to polyurethane (PU) foams due to their advantages for sustainable development and green production. However, the current synthesis of the NIPU foams mainly relies on external foaming agents. In this study, bio-based NIPU foams were developed by a simple self-foaming method composed of two simultaneous processes: S-alkylation of multifunctional thiol compounds and carbonated linseed oil (CLSO) and ring-opening reaction between diamines and CLSO. The effects of curing conditions, thiol functionality, and the types of diamines on the chemical structure, morphology, and properties of the NIPU foams were systematically investigated. The cell diameter of the resulting NIPU foams could be tuned in the range 0.17–1.34 mm, and the compression strength could be tailored in the range 6.7–21.0 kPa. The solvent-free strategy for the synthesis of self-blowing plant oil-based NIPU foams offers a new and simple route for constructing next-generation NIPU foams that are environmentally friendly and have performance advantages.