Synthesis and characterization of hyperbranched polytriazole via an 'A2+ B3' approach based on click chemistry

BACKGROUND: The 'A2+ B3' type of polymerization has been demonstrated to be an alternative route towards hyperbranched polymers. Some highly crosslinked hyperbranched polymers have been prepared via copper(I)-catalyzed click reactions of multivalent azides and alkynes. To obtain hyperbranched polymers without gelation and develop the A(2)+ B-3 type of polymerization based on click reactions, the specific reaction conditions need to be investigated. RESULTS: In this work, a hyperbranched polytriazole (hb-PTA) was synthesized through the A(2)+ B-3 approach using a click reaction. 4-N,N'-bis(2-azidoethyl)amino-4'-nitroazobenzene and 1,3,5-tris(alynyloxy)benzene were synthesized for use as the A(2) and B-3 monomers, respectively. This was a 'one-pot' polymerization carried out using a slow-addition method. The obtained hb-PTA was soluble in common organic solvents. The molecular structure was characterized using H-1 NMR, Fourier transform infrared and gel permeation chromatography analyses. The degree of branching of hb-PTA was determined to be around 0.50. CONCLUSION: The hb-PTA was successfully synthesized via the A(2)+ B-3 approach based on a click reaction. The polymerization conducted in dilute solution adopting slow addition of A(2) to B-3 resulted in hb-PTA in the absence of gelation. The obtained hb-PTA exhibited high thermal stability. (C) 2008 Society of Chemical Industry.