Polyurethanes and polyurethane-ureas, particularly their water-based dispersions, have gained relevance as an extremely versatile area based on environmentally friendly approaches. The evolution of their synthesis methods, and the nature of the reactants (or compounds involved in the process) towards increasingly sustainable pathways, has positioned these dispersions as a relevant and essential product for diverse application frameworks. Therefore, in this work, it is intended to show the progress in the field of polyurethane and polyurethane-urea dispersions over decades, since their initial synthesis approaches. Thus, the review covers from the basic concepts of polyure-thane chemistry to the evolution of the dispersion’s preparation strategies. Moreover, an analysis of the recent trends of using renewable reactants and enhanced green strategies, including the current legislation, directed to limit the toxicity and potentiate the sustainability of dispersions, is described. The review also highlights the strengths of the dispersions added with diverse renewable additives, namely, cellulose, starch or chitosan, providing some noteworthy results. Similarly, dispersion’s potential to be processed by diverse methods is shown, evidencing, with different examples, their suitability in a variety of scenarios, outstanding their versatility even for high requirement applications.This research was funded by the University of the Basque Country (UPV/EHU) (GIU18/216
Research Group), the Spanish Ministry of Science, Innovation and Universities and European Union
(MICINN/EU/FEDER) (MAT2016-76294-R and PID2019-105090RB-I00). Also, the Foundation for
Science and Technology (FCT, Portugal) funded by financial support by national funds FCT/MCTES
to CIMO (UIDB/00690/2020). National funding by FCT- Foundation for Science and Technology,
through the institutional scientific employment program-contract with I.F.info:eu-repo/semantics/publishedVersio
