CHAPTER 3: Facile Synthesis of Multicomponent Star Copolymers via Controlled Polymerization and Click Chemistry

This chapter summarizes the latest progress in the precise synthesis of miktoarm stars via living/controlled polymerization techniques and click reactions. Thus far, living anionic polymerization-based iterative methodologies are the most mature methods to generate multicomponent stars, by which miktoarm stars with five to nine chemical compositions have been achieved. Other synthetic approaches involving ‘arm first’, ‘core first’, ‘coupling onto’, and ‘in–out’ methods have been developed to prepare a wide range of star polymers, and the modular click strategy has allowed the facile construction of well-defined ABCDE star quintopolymers. The introduction of click/click-like reactions, such as copper(i)-catalyzed azide–alkyne cycloaddition, strain promoted azide–alkyne cycloaddition, normal and hetero Diels–Alder cycloaddition, thiol-bearing linking, aldehyde–aminoxy linking, Glaser coupling, and nitroxy radical coupling reactions, has drastically expanded the scope and potential of star copolymers in materials science. Some contents are discussed in this review, including a rough classification, the development of general synthetic strategies, and the potential of each method in tuning the parameters and architectures of star polymers. Based on the selected number of literature examples, it appears that combinatorial methods involving click reactions are a versatile and powerful approach to prepare various miktoarm stars with rich compositions and on-demand functions.