Kinetic study of copper(I)‐catalyzed click chemistry step‐growth polymerization

Abstract

Abstract Oligomers and polymers containing triazole units were synthesized by the copper(I)‐catalyzed 1,3‐dipolar cycloaddition step‐growth polymerization of four difunctional azides and alkynes. In a first part, monofunctional benzyl azide was used as a chain terminator for the polyaddition of 1,6‐diazidohexane and α,ω‐bis(O‐propargyl)diethylene glycol, leading to polytriazole oligomers of controlled average degree of polymerization (DP n = 3–20), to perform kinetic studies on low‐viscosity compounds. The monitoring of the step‐growth click polymerization by 1 H NMR at 25, 45, and 60 °C allowed the determination of the activation energy of this click chemistry promoted polyaddition process, that is, E a = 45 ± 5 kJ/mol. The influence of the catalyst content (0.1–5 mol % of Cu(PPh 3 ) 3 Br according to azide or alkyne functionalities) was also examined for polymerization kinetics performed at 60 °C. In a second part, four high molar mass polytriazoles were synthesized from stoichiometric combinations of diazide and dialkyne monomers above with p ‐xylylene diazide and α,ω‐bis(O‐propargyl)bisphenol A. The resulting polymers were characterized by DSC, TGA, SEC, and 1 H NMR. Solubility and thermal properties of the resulting polytriazoles were discussed based on the monomers chemical structure and thermal analyses. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5506–5517, 2008