Self- blowing non-isocyanate polyurethane foam: Synthesis, characterization and properties

Polyurethane (PU) foams are inevitable for many applications from comfort materials or energy saving to aerospace. Today, greener routes for their production have gained thoughtful attention among the scientific community by avoiding mainly the use of toxic isocyanates. An easily scalable process for the realization of self-blown isocyanate-free PU (poly (hydroxy urethane)-PHU) foams by exploiting suitable amines and cyclic carbonates is demonstrated in this work. The foaming is attributed to the release of CO₂, from the reaction of cyclic carbonate of resorcinol diglycidyl ether (RDGCC) with amine terminated oligomeric phenyl hydroxy amine (AOPHA), where a parallel reaction of the hydroxyl groups and amino groups with the cyclic carbonate groups are competing during polymerization and culminate in poly (hydroxy urethane) foam. The released gas was confirmed as CO₂ from GC–MS and temperature dependent FTIR. The realized flexible PHU foam is thermally stable (>250 ℃) with adhesive strength between Al-Al as 1.5 to 2.0 MPa, and with a closed cell structure possessing a density of 480 kg/m³.