On the Hydrolytic Depolymerization of Polyurethane Foam Wastes by Ionic Liquids

Flexible polyurethane foams (PUFs) are widely used materials whose crosslinked chemical structure hinders conventional recycling, leading to significant environmental challenges. This study presents a selective and scalable depolymerization strategy for polyurethane foam waste (PUFW), utilizing a combination of 1-butyl-3-methylimidazolium chloride ([Bmim][Cl]) as water-miscible ionic liquid (IL) and a strong organic base to enable hydrolytic cleavage of urethane bonds under mild reaction conditions (98 °C, atmospheric pressure). The approach was evaluated across different PUFW formulations and successfully scaled up to a 1 kg reaction mass, maintaining high efficiency in both the depolymerization and separation steps. The recovered polyols exhibited high purity and structural fidelity, comparable to those of virgin polyols. The recycled products were integrated into a new foam formulation, resulting in a PUF with mechanical and morphological properties, as revelated by scanning electron microscopy (SEM), which closely resemble those of virgin polyol-based references and surpass those of foams produced using commercially recycled polyols. These findings support the feasibility of closed-loop polyurethane recycling and represent the transition towards circular polymer economy strategies.