# Sustainable Polyurethane Systems: Integrating Green Synthesis and Closed-Loop Recovery

## TL;DR

This review explores sustainable polyurethane systems by combining eco-friendly synthesis methods with recycling techniques to reduce environmental impact.

## Contribution

The paper integrates green synthesis and closed-loop recovery strategies for polyurethanes into a unified sustainable framework.

## Key findings

- Bio-based polyols and phosgene-free isocyanates from renewable resources reduce reliance on petrochemicals.
- Chemical recycling methods like acidolysis and aminolysis enable recovery of high-purity monomers.
- PU vitrimers and DCPNs offer reprocessable structures with thermoset-like durability.

## Abstract

Polyurethanes (PUs) are indispensable polymeric materials widely employed across diverse industrial sectors due to their excellent thermal stability, chemical resistance, adhesion, and mechanical durability. However, the intrinsic three-dimensional crosslinked network that underpins their performance also presents a fundamental barrier to reprocessing and recycling. Consequently, most end-of-life PU waste is currently managed through landfilling or incineration, resulting in significant resource loss and environmental impact. To address these challenges, this review presents an integrated perspective on sustainable PU systems by unifying green synthesis strategies with closed-loop recovery approaches. First, recent advances in bio-based polyols and phosgene-free isocyanate synthesis derived from renewable resources—such as plant oils, carbohydrates, and lignin—are discussed as viable means to reduce dependence on petrochemical feedstocks and mitigate toxicity concerns. Next, emerging chemical recycling methodologies, including acidolysis and aminolysis, are reviewed with a focus on the selective recovery of high-purity monomers. Finally, PU vitrimers and dynamic covalent polymer networks (DCPNs) based on urethane bond exchange reactions are examined as reprocessable architectures that combine thermoplastic-like processability with the mechanical robustness of thermosets. By integrating synthesis, recovery, and reuse within a unified framework, this review aims to outline a coherent pathway toward establishing a sustainable circular economy for PU materials.