Preparation and properties of phenyl‐modified natural rubber |
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Authors: | Seiichi Kawahara Shintaro Shioyama Choothong Nuorn Lina Fukuhara Hiroyuki Ishii Yoshimasa Yamamoto Katsuhiko Takenaka |
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Institution: | 1. Department of Materials Science and Technology, Nagaoka University of Technology, Niigata, Japan;2. Department of Chemical Science and Engineering, Tokyo National College of Technology, Tokyo, Japan |
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Abstract: | We prepared phenyl‐modified natural rubber using a two‐step process. In the first step, natural rubber was brominated using N‐bromosuccinimide in a dichloromethane solution of natural rubber. The amount of N‐bromosuccinimide controlled the bromine content. In the second step, a Suzuki–Miyaura cross‐coupling reaction of the brominated natural rubber with phenyl boronic acid in the presence of a palladium catalyst replaced the bromine atoms with phenyl groups. 1H‐nuclear magnetic resonance and 13C‐nuclear magnetic resonance measurements characterized the products. The signals around 7 ppm in the 1H‐nuclear magnetic resonance spectra of the products were assigned to the phenyl protons, and based on the assigned signals, the estimated conversion of the cross‐coupling reaction under mild conditions was more than 70 mol%. The amount of phenyl groups present affected both the loss tangent and the glass transition temperature of natural rubber, which increases from ?62°C to ?30°C. Copyright © 2015 John Wiley & Sons, Ltd. |
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Keywords: | natural rubber Suzuki– Miyaura cross‐coupling reaction NMR |
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