Green and Sustainable Chemistry Approaches on Azide-Based Click Reactions in Polymer Science.

Click Chemistry, particularly the azide-alkyne cycloaddition (AAC) reaction, has revolutionized polymer chemistry, enabling precise and efficient synthesis of advanced functional materials. With its high regioselectivity, mild reaction conditions, and versatility, AAC reactions align closely with the principles of Green and Sustainable Chemistry. However, the core principles of Click Chemistry, particularly its compatibility with Green Chemistry ideals-such as reduced waste, high atom economy, and mild reaction conditions-remain insufficiently emphasized in the context of polymer chemistry. The review evaluates current limitations in AAC-particularly the challenges associated with hazardous azide reagents and reliance on non-renewable resources-and explores innovative solutions, including greener catalysts, solvent-free systems, and the incorporation of renewable feedstocks. Additionally, the review presents a comparison of activation methods, spanning thermal, catalytic, metal-free, and strain-promoted pathways, to highlight their respective advantages and trade-offs in sustainability. Practical applications of AAC in polymer design are discussed, showcasing its role in creating materials with tailored properties such as thermal stability, bioactivity, and electronic functionality. This analysis provides a roadmap for future research to optimize AAC for sustainability without compromising its effectiveness in materials design.