Novel Strategy to Synthesize Low-molecular-weight and High Trans-1,4 Polyisoprene (Chemistry)

Synthetic rubber especially low-molecular-weight and high trans-1,4 polyisoprene liquid rubber have been widely applied. At present, cationic polymerization is the dominant way to prepare high trans-1,4 polyisoprene.

However, it faces the challenge of uncontrolled cyclization or branching side reactions. It’s important to develop highly effective cationic polymerization system to produce high trans-1,4 polyisoprene liquid rubber with high double bond content.

Recently, a research group led by Prof. WANG Qinggang from the Qingdao Institute of Bioenergy and Bioprocess Technology (QIBEBT) of the Chinese Academy of Sciences developed a novel strategy of protonic acid and ionic liquid catalysis to synthesize low-molecular-weight and high trans-1,4 polyisoprene.

The study was published in Macromolecules on June 29.

The synergistic effect of Tf2NH and ionic liquid including Tf2N counter anion performed well, affording high yield (> 99%) and high double bond content (up to 99%) simultaneously.

Mechanistic investigation indicated that a weak interaction between the double bonds and bulky cations could reduce the elctrondensity of double bonds in polyisoprene to prevent the undesired “re-protonation”. Furthermore, high performance can still be maintained after ionic liquid was recycled for five rounds. 

The above advantages provide a feasible green pathway for the industrial production of high trans-1,4 polyisoprene liquid rubber. 

Featured image: High trans-1,4 polyisoprene liquid rubber polymerization. (Image by ZHU Guangqian and WANG Liang)

Provided by Chinese Academy of Sciences

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