Immobilization of copper(II)-poly(N-vinylimidazole) complex on magnetic nanoparticles and its catalysis of oxidative polymerization of 2,6-dimethylphenol in water

Poly(N-vinylimidazole) (PVI) was grafted onto magnetic Fe₃O₄ nanoparticles through siloxane bonds to produce PVI-grafted Fe₃O₄ nanoparticles (shortened as Fe₃O₄-g-PVI). The amount of imidazolyl groups in Fe₃O₄-g-PVI was estimated to be 1.16 mmol/g by elemental analysis and thermal gravimetric analysis. The Fe₃O₄-g-PVI coordinated with Cu(II) to form the immobilized Cu(II)-PVI complex. The stoichiometric ratio between imidazolyl groups in Fe₃O₄-g-PVI and Cu(II) was found to be 4 and the complex formation constant (K) was calculated to be 5.6 × 10¹⁴ mol⁻⁴ L⁴. The immobilized Cu(II)-PVI complex was employed to catalyze the oxidative polymerization of 2,6-dimethylphenol (DMP) in water and showed excellent C O/C C selectivity to form PPO. After polymerization, the immobilized Cu(II)-PVI complex catalyst was collected by an external magnetic field and reused in the next run with additional immobilized catalyst and copper ions. After three runs of oxidative polymerization of DMP, the recovery rate of the immobilized Cu(II)-PVI catalyst was above 95% and the yield of PPO maintained as high as 79.2% with the addition of supplementary catalysts. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012