PhD Defence Ege Hosgor | Chemical recycling of polyurethane foam using organic carbonates: A journey towards circularity

Chemical recycling of polyurethane foam using organic carbonates: A journey towards circularity

Ege Hosgor is a PhD student in the Department of Molecular Nanofabrication. (Co)Promotors are prof.dr.ir. J. Huskens, prof.dr. J. Lange and dr. W. Verboom from the Faculty of Science & Technology.

Polyurethanes (PU) are among the most versatile classes of synthetic polymers in material science. Their chemistry allows control over mechanical, thermal and structural properties by reacting polyols with diisocyanates. Among these materials, flexible polyurethane foams (PUFs) are widely used in everyday applications such as mattresses, furniture, and car seats. However, they are extremely challenging to recycle because of their crosslinked structure. As global PU production continues to grow, conventional disposal routes such as landfilling and incineration conflict with sustainability goals. Chemical recycling has emerged as a promising strategy to depolymerize these materials into smaller molecular building blocks. The majority of the methods focus primarily on recovering the polyol fraction, while the aromatic fraction is often lost as low-value residues. From circular economy perspectives, this limitation represents a fundamental barrier to achieving truly closed-loop recycling of PUF materials.

In this thesis, our goal is to develop chemical recycling strategies that enable the recovery of both PU building blocks in a phosgene-free and potentially circular manner. The research focused on carbonate-assisted carbonyl exchange reactions as a pathway to depolymerize flexible PUFs into alkoxycarbonyl-functionalized intermediates, which result in new opportunities for separation. Beyond depolymerization, this work explores the potential of the conversion of these intermediates back to reactive monomers or their direct use in non-isocyanate PUs. In doing so, the research aims to bridge PU waste depolymerization with future polymer synthesis, addressing a central question in sustainable polymer chemistry: how can PU materials be chemically designed and recycled in ways that enable truly circular material lifecycles?