Copper-based ionic liquid-catalyzed click polymerization of diazides and diynes toward functional polytriazoles for sensing applications

Click polymerizations of azides and alkynes catalyzed by Cu(I) species have been widely studied and play a significant role in polymer synthesis. In these approaches, long reaction time and/or elevated temperature are generally required. Fabrication of new catalytic systems with higher efficiency and an energy saving feature is still a key challenge. In this work, an efficient copper-based ionic liquid (Cu-IL) is facilely prepared and used to catalyze the azide–alkyne click polymerization under mild reaction conditions. Soluble and thermally stable 1,4-regioregular polytriazoles (PTAs) with satisfactory molecular weights (up to 56 100) are readily synthesized in high yields (up to 95%). Thanks to its intense blue fluorescence and excellent water-solubility, the resultant ionic PTA could be applied for sensitive explosive detection, selective Fe³⁺ ion recognition and specific bioimaging in its aqueous solution. Thus, this work not only establishes a powerful Cu-IL-catalyzed azide–alkyne click polymerization but also provides PTAs with versatile properties.