Macromonomer derived from tung oil and bismaleimide: synthesis via Diels-Alder reaction and production of renewable polyesters

Abstract

Polymers are essential materials in modern society, supporting technological development and improving quality of life. In response to growing environmental concerns, the development of polymers from renewable resources has gained attention. Among bio-based feedstocks, vegetable oils have emerged as versatile and abundant alternatives to petrochemical sources. Notably, tung oil stands out due to its high content of conjugated double bonds, enabling unique reactivity for polymer synthesis. In this context, the present work proposes a simple and yet novel approach: the transesterification of tung oil to methyl α-eleostearate, followed by Diels-Alder coupling with commercial aromatic bismaleimide to obtain a diester monomer, which was subsequently copolymerized into renewable polyesters. The results contribute to expanding the utility of tung oil in sustainable polymer development through efficient, bio-based synthetic routes. The envisaged molecular structure of the tung oil-based monomer was confirmed by FTIR and ¹H NMR spectroscopy. Subsequent polycondensation with various diols yielded polyesters with number-average molecular weights up to 7,100 g/mol. The incorporation of 10 mol% furan-based comonomer notably improved the materials’ thermal properties, increasing Td₅% by up to 58 °C and raising glass transition temperatures, while potentially reducing crystallinity. Overall, the integration of Diels-Alder chemistry and polycondensation using renewable feedstocks offers a promising route for developing sustainable polymers with tunable thermal properties.