Metal‐Free Poly‐Cycloaddition of Activated Azide and Alkynes toward Multifunctional Polytriazoles: Aggregation‐Induced Emission, Explosive Detection, Fluorescent Patterning, and Light Refraction

Abstract

The metal‐free click polymerization (MFCP) of activated alkynes and azides or activated azide and alkynes have been developed into powerful techniques for the construction of polytriazoles without the obsession of metallic catalyst residues problem. However, the MFCP of activated azides and alkynes is rarely applied in preparation of functional polytriazoles. In this paper, soluble multifunctional polytriazoles (PIa and PIb) with high weight‐average molecular weights (Mw up to 32 000) are prepared via the developed metal‐free poly‐cycloaddition of activated azide and alkynes in high yields (up to 90%). The resultant PIa and PIb are thermally stable, and show aggregation‐induced emission characteristics, enabling their aggregates to detect explosives with superamplification effect. Moreover, thanks to their containing aromatic rings and polar moieties, PIa and PIb exhibit high refractive indices. In addition, they can also be cross‐linked upon UV irradiation to generate 2D fluorescent patterning due to their remaining azide groups and containing ester groups. Thus, these multifunctional polytriazoles are potentially applicable in the optoelectronic and sensing fields.

Click chemistry strategies for the accelerated synthesis of functional macromolecules

“…Tang has explored these reactions extensively for metal-free polymerization. 29,30 Electronically activated alkynes, such as aroylacetylene, 31 propiolate, 32 and azides that are electron-deficient, such as perfluorophenyl azide, 33,34 are reported to undergo efficient polymerization.…”

In Situ Generation of Heterocyclic Polymers by Triple‐Bond Based Polymerizations

“…Through the facile and highly efficient click polymerizations of aliphatic or aromatic diynes and diazides, a wide variety of poly(imidazole)s have been constructed. [28][29][30][31][32][33][34][35] In addition to click polymerizations, other representative progress will be discussed herein by classifying via the triple-bond building blocks (isonitriles and alkynes). As depicted in Scheme 2, a series of isonitrile-based polymerizations have been developed for the in-situ synthesis of heterocyclic polymers in recent few years.…”

Progress on Catalytic Systems Used in Click Polymerization

“…Interestingly, the regioregularities of the polymers could be fine‐tuned by the solvents and diyne monomers . In addition, TPE and silole moieties could be easily incorporated into the backbones of PTAs to render them with novel properties, such as AIE, high refractive indices and fluorescent photopatterning …”