Metal-free polycycloaddition of aldehyde-activated internal diynes and diazides toward post-functionalizable poly(formyl-1,2,3-triazole)s

Azide–alkyne click polymerization has become a powerful and popular technique for the preparation of polytriazoles with diverse topological structures and versatile properties. However, the synthesis of post-functionalizable 1,4,5-trisubstituted polytriazoles (1,4,5-PTAs) is still a challenge. In this work, a metal-free polycycloaddition of aldehyde-activated internal diynes and diazides is developed, and a series of soluble and thermally stable poly(formyl-1,2,3-triazole)s (formyl-PTAs) with high weight-average molecular weights (Mw, up to 54 550) are facilely produced in high yields (up to 93%). The tetraphenylethene moiety containing formyl-PTAs exhibit unique aggregation-induced emission features. Moreover, the aldehyde groups at the C-5/C-4 positions of triazole rings in the formyl-PTA enable it to be a highly selective chemosensor for hydrazine detection and to serve as a useful platform for further post-functionalization, enriching the properties of proto-polytriazole as desired. Thus, this work combines a metal-free approach toward 1,4,5-PTAs with a post-functionalization strategy to pave a way for the development of a multitude of functional polytriazole-based materials.