Thiol-Epoxy Click Chemistry and Its Applications in Macromolecular Materials

As one kind of "click chemistry", thiol-epoxy reaction has drawn intensive attention in recent years due to its outstanding advantages, such as fast reaction rate, high selectivity, and mild reaction conditions. This review illustrates the base-catalyzed mechanism of thiol-epoxy reaction in details. The influences of base catalysts, substituent groups and solvents on the thiol-epoxy reaction rate are summarized. The inorganic base such as lithium hydrate and organic base such as tetrabutylammonium fluoride are excellent catalytic activity. The advantages and disadvantages of inorganic and organic base catalysts are compared as well. Thiols with electron donating groups and epoxy with electron-withdrawing groups are more active, which are also influenced by steric effect. The reactions in bulk system usually have higher yield than the reactions in solution. Moreover, the applications of thiol-epoxy reaction in macromolecular materials are also demonstrated and classified into two types according to their different focuses; one is synthesis of structure-controllable macromolecules in the solvents, including the synthesis of macromolecules with linear or complicated structures and the modifications of macromolecules or surfaces; and the other one is preparation of crosslinking polymeric networks with excellent properties and practical potential in the bulk condition. Furthermore, the trends of thiol-epoxy reaction are prospected in brief.