Polymerization of phenols catalyzed by peroxidase in nonaqueous media

Polymers produced by horseradish‐peroxidase‐catalyzed coupling of phenols have been explored as potential substitutes for phenol‐formaldehyde resins. To overcome low substrate solubilities and product molecular weights in water, enzymatic polymerizations in aqueous‐organic mixtures have been examined. Peroxidase vigorously polymerizes a number of phenols in mixtures of water with water‐miscible solvents such as dioxane, acetone, di‐methylformamide, and methyl formate with the solvent content up to 95%. As a result, various phenolic polymers with average molecular weights from 400 to 2.6 × 10⁴ D were obtained depending on the reaction medium composition and the nature of the phenol. Peroxidase‐catalyzed copolymerization of different phenols in 85% dioxane was demonstrated. Poly(p‐phenylphenol) and poly(p‐cresol) were enzymatically prepared on a gram scale. They had much higher melting points, and in addition, poly(p‐phenylphenol) was found to have a much higher electrical conductivity than phenol‐formaldehyde resins.