Triazolinediones enable ultrafast and reversible click chemistry for the design of dynamic polymer systems

Stijn Billiet, Kevin De Bruycker, Frank Driessen, Hannelore Goossens, Veronique Van Speybroeck, Johan M. Winne, Filip E. Du Prez

With its focus on synthetic reactions that are highly specific and reliable, 'click' chemistry has become a valuable tool for many scientific research areas and applications. Combining the modular, covalently bonded nature of click-chemistry linkages with an ability to reverse these linkages and reuse the constituent reactants in another click reaction, however, is a feature that is not found in most click reactions. Here we show that triazolinedione compounds can be used in click-chemistry applications. We present examples of simple and ultrafast macromolecular functionalization, polymer-polymer linking and polymer crosslinking under ambient conditions without the need for a catalyst. Moreover, when triazolinediones are combined with indole reaction partners, the reverse reaction can also be induced at elevated temperatures, and the triazolinedione reacted with a different reaction partner, reversibly or irreversibly dependent on its exact nature. We have used this 'transclick' reaction to introduce thermoreversible links into polyurethane and polymethacrylate materials, which allows dynamic polymer-network healing, reshaping and recycling.