# Closing the Loop on Polyurethane Foam Waste: Challenges, Emerging Technologies, and the Road to Sustainable Circularity

## TL;DR

This paper reviews chemical recycling methods for polyurethane foam waste, focusing on glycolysis and acidolysis, and highlights their progress toward sustainable circular economy solutions.

## Contribution

The paper provides a critical overview of chemical recycling technologies for polyurethane foam waste and identifies pathways for industrial implementation.

## Key findings

- Glycolysis is a mature technology for recovering high-purity polyols from PUF waste.
- Acidolysis offers milder conditions and faster kinetics with reduced toxic byproducts.
- Hybrid processes and biotechnological approaches are emerging but remain at low technology readiness levels.

## Abstract

The increasing production of polyurethane foams (PUFs)
and their
inherently cross-linked, recalcitrant structure pose major challenges
for waste management and circular economy implementation. While mechanical
recycling remains the preferred option for thermoplastics, its applicability
to thermoset materials such as PUFs is severely limited. Chemical
depolymerization has therefore emerged as a key strategy for closing
the loop on PUF waste (PUFW). This review provides a critical overview
of the chemistry, mechanisms, and technological readiness of the main
chemical recycling pathwaysparticularly glycolysis and acidolysishighlighting
their reaction dynamics, process parameters, and environmental implications.
Glycolysis stands out as a mature and versatile technology capable
of recovering high-purity polyols under optimized catalytic conditions,
whereas acidolysis using (di)­carboxylic acids offers milder operation,
faster kinetics, and reduced release of toxic aromatic amines. Hybrid
processes that combine both approaches are now entering industrial
deployment, as demonstrated by large-scale consortia, such as Renuva,
Circufoam, and Recpur, which collectively illustrate the progression
from laboratory research to pilot-scale or commercial implementation.
Additionally, emerging biotechnological routesencompassing
enzymatic depolymerization and nonisocyanate polyurethane synthesisand
Dynamic Covalent Polymer Networks (DCPNs) approaches are discussed
as complementary long-term solutions, though they remain at low technology
readiness levels (TRL < 4). Overall, this review identifies the
current advances, limitations, and prospects of PUF chemical recycling
technologies and provides a roadmap for integrating these strategies
into sustainable polymer value chains within a truly circular economy
framework.