Oxidative degradation of cis- and trans-1,4-polybutadienes by horseradish peroxidase/1-hydroxybenzotriazole

Abstract

Emulsions of cis- and trans-1,4-polybutadienes and cast films of trans-1,4-polybutadiene were treated by an enzyme-mediator system, horseradish peroxidase/1-hydroxybenzotriazole (HRP/1-HBT), at 37 °C for 48 h. Gel permeation chromatography showed that the HRP/1-HBT system was capable of degrading both emulsified 1,4-polybutadienes significantly, but not cast films of trans-1,4-polybutadiene. The weight-average molecular weights of the emulsions after the enzymatic treatment reduced to 34% and 38% of the values for the starting polymers, for cis- and trans-1,4-polybutadienes, respectively. In their infrared spectra, strong absorption bands appeared at 1100 cm −1 and 1111 cm −1 which are assigned to C–O groups for cis- and trans-1,4-polybutadienes, respectively. These results suggest that oxidation of 1,4-polybutadienes progresses during the treatment by HRP/1-HBT system to introduce oxygen atoms into the polymer chains.