Green polyurethanes from bio-based building blocks: recent advances and applications

Polyurethanes (PUs) are among the most studied, manufactured, and employed polymers thanks to their versatility and wide range of applications. However, their synthesis generally relies on toxic, non-renewable and harmful petroleum-based chemicals. In recent decades, driven by urgent environmental needs, research activities for the development of alternative synthetic routes for their production have grown enormously, especially to find more sustainable raw materials and procedures that, for example, no longer require dangerous solvents. Given these premises, the main purpose of this review is to highlight the most recent advances in the production of bio-derived polyurethanes. After briefly discussing the chemistry of polyurethanes, we focused on the generation of bio-polyols and bio-isocyanates from plant oils and lignocellulosic biomass (e.g. lignin and sugars), as well as on the most recent trends in nonisocyanates polyurethanes (NIPUs) production. Discussions on their fields of application will be key to giving readers an overview of the actual capabilities of these materials. This review aims to cover and discuss the most recent contributions appearing in the literature up to the beginning of 2023.