Non-isocyanate polyurethane foams derived from 1,1’-carbonyldiimidazole functionalized precursors

Polyurethanes are some of the most prevalent materials in the industrial sphere because of their versatility. They exhibit exceptional hardness, strength, and flexibility based on chemical structure, affording diverse applications such as coatings, adhesives, foams, elastomers, and fibers. Academia and industry are working towards phasing out isocyanates, which are well known for being toxic, hazardous, and highly reactive. Since isocyanates are one of the two-component polyurethane systems, it is imperative to investigate new routes to polyurethane thermoplastics and foams. There are four major pathways towards non-isocyanate polyurethanes (NIPUs). These include carbonates and carbamates reacting with amines or alcohols, respectively. The Long research group recently discovered a novel method of reacting imidazole-activated diols with amines to produce NIPUs. The products range from thermoplastics to thermoset polyurethane foams based on the reagent functionality and chemical structure. The glass transition temperatures are tunable from below 0 °C to above 130 °C based on differential scanning calorimetry, dynamic mechanical analysis, and thermomechanical analysis. The reaction is highly versatile and is sustainable because it is catalyst-, solvent-, and isocyanate-free.

Isocyanate-free polyurethane foam with scanning electron microscopy image.