Ethynyl-Capped Hyperbranched Conjugated Polytriazole: Click Polymerization, Clickable Modification, and Aggregation-Enhanced Emission

Cu(I)-catalyzed azide-alkyne click polymerization, developed based on the click reaction, has become a powerful tool for the construction of functional polytriazoles with linear and hyperbranched structures. This method has, however, rarely been used for the preparation of functional hyperbranched conjugated polytriazoles (hb-CPTA). In this paper, soluble ethynyl-capped hb-CPTA with weight-averaged molecular weight of 39 500 was synthesized in high yield (84.4%) by the Cu(I)-catalyzed azide-alkyne click polymerization of tetraphenylethene containing diazide [1,2-bis(4-azidophenyl)-1,2-diphenylethene] and tetrayne [1,1,2,2-tetrakis(4-ethynylphenyl)ethane] in equal concentration. By taking advantage of the ethynyl groups on its periphery, the polymer could be efficiently postfunctionalized by azide-alkyne and thiol-yne click reactions. The polymers are thermally stable and loss 5% of their weights at temperatures higher than 340.0 degrees C. hb-CPTA also possesses high char yield (74.8%) at 800 degrees C. The polymers feature the unique characteristics of aggregation-enhanced emission. Furthermore, the PL intensities of the hb-CPT A and thiol-yne postfunctionalized polytriazoles increase linearly with water fraction in THF/water mixtures. Thanks to their rigid structures, the polymers could be fabricated into unimolecular nanoparticles with sizes of ca. 100 nm. Thus, this paper provides a powerful method to synthesize soluble ethynyl-capped hyperbranched polymers, which could be a useful platform for preparation of versatile functional polymers via postreactions.