Effective Synthesis of Poly(2,6-Dimethyl-1,4-Phenylene Oxide) Derivatives by Oxidative Coupling Copolymerization of Alkoxyphenols with Copper(II) Catalyst

Abstract

The oxidative coupling copolymerization between 2,6-dimethylphenol (DMP) and phenols having various alkoxy groups, such as methyoxy (MOP), ethoxy, benzyloxy, butoxy, and 2-hydroxyethoxy groups, was carried out using a copper(II) catalyst under an O₂ atmosphere. The copolymerizations with alkoxyphenols effectively proceeded, and the unit ratios of the obtained copolymers were in good agreement with those in the feed. The coupling regioselectivity, such as oxyphenylene (CO) and phenylene (CC), of the alkoxyphenol unit constructed during the copolymerization was also estimated by the ¹H NMR analysis of the acetylated polymer. As an example, the copolymer with the unit ratios of DMP:p-MOP = 50:50 and CO:CC = 67:33, was obtained in 71% yield during the copolymerization with p-MOP (feed ratio, 50:50) in a mixed solvent of CH₂Cl₂ and methanol (7/1 (v/v)) for 24 h. The solubility and thermal property of the obtained copolymers were significantly affected by the structure of alkoxyphenol unit.