Miscellaneous Click and Click-like Reactions in Polymer Science

Click chemistry approaches have directed the materials research community to access a diverse range of complex polymeric systems. Click chemistry involves exploiting the easy-to-execute chemical reactions that can be performed at ambient conditions while being efficient and rapid. Macromolecular engineering with click chemistry requires the explicit installation of clickable reactive groups on polymer side chains or chain ends. The copper(i)-catalyzed azide–alkyne (CuAAC) cycloaddition is the most prominent click reaction in polymer science. However, the Cu catalyst needs to be removed for many applications (especially in bio-applications), complicating the use of CuAAC. Therefore, several metal-free click reactions, including Diels–Alder, Alder-ene, thiol-X, amine-X, and electrophilic substitution, have been developed for the preparation of functional (bio)polymer materials, many of which were inspired by old organic chemistry literature. Some of these reactions don’t follow all the click criteria, although they are very effective in joining the building blocks. Hence, they are termed click-like reactions. This chapter briefly highlights some less exploited or newly explored click and click-like reactions for polymer science, such as carbonyl-condensation hydrazine and oxime reactions, the boronate–ester exchange reaction, transclick reactions, and supramolecular click chemistry.