Oxidative Degradation of trans-1,4-Polyisoprene Cast Films and Single Crystals by Enzyme-Mediator Systems
✍ Scribed by Makiko Enoki; Yoshiharu Doi; Tadahisa Iwata
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 217 KB
- Volume
- 3
- Category
- Article
- ISSN
- 1616-5187
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✦ Synopsis
Abstract
Depolymerization and morphological changes of cast films and single crystals of trans‐1,4‐polyisoprene with three enzyme‐mediator systems, lipoxygenase/linoleic acid (LPO/LH), horseradish peroxidase/1‐hydroxybenzotriazole (HRP/1‐HBT) and laccase/1‐hydroxybenzotriazole/linoleic acid (laccase/1‐HBT/LH), were investigated by scanning electron microscopy and gel permeation chromatography. Treatment of cast film with a LPO/LH system involving radical generation via lipid peroxidation led to a marked decrease in the molecular weight of polymers. LPO/LH system resulted in the morphological damage of single crystals of trans‐1,4‐polyisoprene. Laccase/1‐HBT/LH also destroyed the single crystals and depolymerized emulsified trans‐1,4‐polyisoprene. On the contrary, spherulites appeared on the surface of cast films and the molecular weight slightly decreased after treatment with HRP/1‐HBT, indicating that the amorphous region was predominantly degraded and the crystal region remained unchanged. The morphology of single crystals remained unchanged during the treatment of HRP/1‐HBT system for 6 d. In addition, Fenton reagent/linoleic acid was used as a chemical initiator of lipid peroxidation for degradation of trans‐1,4‐polyisoprene cast films. This system reduced molecular weight of the cast films, as well as LPO/LH system.
Scanning electron micrographs of trans‐1,4‐polyisoprene single crystals before (A) and after (B) treatment with the lipoxygenase/linoleic acid system.
magnified imageScanning electron micrographs of trans‐1,4‐polyisoprene single crystals before (A) and after (B) treatment with the lipoxygenase/linoleic acid system.