Sustainable Polyurethanes: From Renewable Building Blocks to Circular Materials

Abstract

The year 2026 marks a significant milestone in the history of polymer science: the 90th anniversary of the pioneering experiments conducted by Otto Bayer in 1936, which laid the foundation for polyurethane chemistry and led to the first polyurethane patent in 1937. Few polymer families have experienced such remarkable scientific and industrial development over nine decades. From their initial conception as versatile synthetic materials, polyurethanes have evolved into one of the most important classes of polymers worldwide, with applications spanning flexible and rigid foams, coatings, adhesives, sealants, elastomers, composites, textiles, electronics, transportation, construction, and biomedical devices. Polyurethanes now represent the sixth largest family of commercial polymers, and the timing is right to enhance their sustainability and circularity for broader impact.

Today, global polyurethane production exceeds 25Mt/y, and the market continues to expand, driven by increasing demand for energy-efficient buildings, lightweight transportation systems, advanced consumer products, and emerging healthcare technologies. Market analysts predict sustained growth over the coming decade, particularly in Asia-Pacific regions, where rapid industrialization and urbanization continue to stimulate demand. At the same time, environmental concerns, regulatory pressure, and societal expectations are profoundly reshaping the future of polyurethane materials. Opportunities for non-isocyanate-based synthetic methods, together with strategies to tackle end-of-life (EOL) are showcased in this special issue. Jin et al. have demonstrated an energy efficient extrusion process to depolymerize crosslinked polyurethane foams in the melt state, thus eliminating the need for organic solvents (https://doi.org/10.1002/macp.202500494). Korley et al. highlights the potential for lignin derived polyurethanes (https://doi.org/10.1002/macp.202500433), and Epps et al. further define potential for lignin derived polyurethanes in the absence of isocyanates (https://doi.org/10.1002/macp.202500230). As polyurethane science and engineering enter its tenth decade, the challenge is no longer simply to produce materials with outstanding performance, but to ensure that these materials are designed, manufactured, used, and recycled in a sustainable manner. This transition is driving one of the most significant transformations in the history of polyurethane research and development.

Looking ahead, the future of polyurethane materials appears both promising and challenging. Global demand is expected to continue growing across sectors such as insulation, mobility, electronics, healthcare, and renewable energy. Polyurethane foams will remain indispensable for improving building energy efficiency and reducing greenhouse gas emissions through thermal insulation. Emerging applications in batteries, electronics, additive manufacturing, and biomedical engineering are also expected to create new opportunities for innovation. Dong et al. describe emerging applications in health sciences with the discovery of vascular grafts (https://doi.org/10.1002/macp.202500490). However, future growth must be reconciled with increasingly ambitious sustainability objectives. The next generation of polyurethane technologies will likely be characterized by greater reliance on renewable carbon sources, reduced dependence on toxic intermediates, improved recyclability, and lower life-cycle environmental impacts. Non-isocyanate polyurethanes, dynamic covalent networks, recyclable thermosets, and carbon-neutral feedstocks are expected to play increasingly important roles in this transition. For example, Wang et al. describe recent advances in alternative isocyanate-free synthetic methods combined with bio-sourced isoprene, leading to a more sustainable synthetic method (https://doi.org/10.1002/macp.202500448). This special issue presents two comprehensive reviews on the latest directions for polyurethanes; Zhang et al. review the development of polyurethane foams in biomedical devices (https://doi.org/10.1002/macp.202500449) and Mazurek–Budzyńska et al. envision the polyurethane field from amino acids to nature-inspired compositions with enabling structure-property relationships (https://doi.org/10.1002/macp.70295). Bakkali–Hassani et al. examine poly(hydroxy urethanes) (PHUs) utilizing ester-containing six-membered cyclic carbonates to yield dual dynamic networks that improve covalent adaptable network (CAN) reprocessing efficiencies. CANs represent an exciting new direction in network design that aims to enable sustainability and more versatile processing. Meier et al. continue the emphasis on more sustainable reaction pathways, and thermally initiated thiol-ene polyaddition is promising for the synthesis of high-performance, isocyanate-free polyurethane materials with potential applications in coatings, adhesives, and thermoplastics.

Artificial intelligence, high-throughput experimentation, and advanced molecular modelling will further accelerate the discovery of sustainable polyurethane formulations, enabling more efficient optimization of material performance while minimizing environmental burdens. In parallel, life-cycle assessment (LCA), technoeconomic analysis (TEA), and circular-design methodologies will become essential tools for evaluating and guiding innovation.

Ninety years after Otto Bayer's pioneering work, polyurethane science stands at another turning point. The remarkable versatility that enabled the success of polyurethane materials throughout the twentieth century now provides the foundation for their reinvention in the twenty-first. The contributions gathered in this special issue demonstrate that sustainability is no longer a peripheral consideration but a central driver of innovation. They collectively illustrate how polyurethane chemistry is evolving toward safer, renewable, circular, and high-performance materials capable of meeting the demands of future generations.

If the first 90 years of polyurethane science were devoted to maximizing performance, the next 90 years will likely be defined by the ability to combine performance with sustainability.