Organic/aqueous interfacial synthesis of poly(2,6-dimethyl-1,4-phenylene oxide) using surface-active copper complex catalysts

The coupling polymerization of 2,6-dimethylphenol to poly(2,6-dimethyl- 1,4 -phenylene oxide) was carried out in an aqueous-chloroform biphasic mixture using copper complexes of substituted ethylenediamines as surface-active c atalysts. Copper-N,N-dibutylethylenediamine complex gave the highest reacti on rate and produced a polymer with an average molecular weight of 48 000 i n a 95% yield. The optimum ligand to catalyst ratio and organic to aqueous volume ratio were found to be 3 : 1 and 1 : 1, respectively. The reaction r ate also depended strongly on the aqueous ammonia concentration, stirring s peed and the emulsifier concentration, The reaction orders with respect to the substrate, catalyst complex and oxygen are 1.0, 1.7 and 0.1, respective ly, and the activation energy was approximately 11.7 kcal/mol. A reaction m echanism is proposed which yields a model rate expression in good agreement with the experimental findings. (C) 2000 Elsevier Science B.V. All rights reserved.