Tracking side reactions of the inverse vulcanization process and developing monomer selection guidelines

Recently, inverse vulcanization has attracted attention because of its utilization of surplus resources and the functionality of the resulting polymeric products. However, details of the byproducts and side reactions are not well known because most of the polymers obtained by inverse vulcanization have complex crosslinked structures, making it difficult to analyze the byproducts. The structures generated by side reactions may adversely affect physical properties; therefore, the objective of this study is to develop guidelines for monomer selection in inverse vulcanization. For this purpose, various olefin monomers were inverse-vulcanized, and their side reactions were traced. From the structural analysis of the products, we identified the terminal structures caused by chain transfer and the byproduct that may contribute to some of the coloration of the polymer. Subsequent evaluation of the thermal stability indicated that the terminal structures of the polymers obtained from aromatic and aliphatic terminal olefins increased upon heating. In contrast, the polymer obtained from aliphatic internal olefin is stable with no such structural changes. These results provide the guidelines for monomer selection in inverse vulcanization.