Renewable eugenol-based functional polymers with self-healing and high temperature resistance properties
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A novel small molecule 1,3-bis(eugenyl) glycerol diether is synthesized from renewable eugenol and epichlorohydrin in 60% total yield, and its structure is confirmed by 1H–NMR spectrum. Then, this small molecule is utilized to prepare oligomer, linear polymer and the corresponding crosslinked polymer (denoted as P 2 ) by using thiol-ene and thiol-oxidation reactions. The polymer P 2 can form brown film on a glass substrate and can be easily put off from the substrate. Mechanical properties of P 2 show that tensile strength value is about 6 MPa, with elongation at break of around 300%. Glass transition temperature (Tg) of P 2 is −2.76 °C, meaning that P 2 is at rubber state. There are hydroxyl groups in the prepared linear polymer, which further reacts with 1,6-hexanediisocyanate (HDI) to form polyurethane P 4 with crosslinked structures. Compared with P 2 , the polyurethane P 4 forms yellow film on a glass substrate. But the film of P 4 is not so flexible as that of P 2 , presumably because of relatively higher Tg (5.85 °C) of P 4 than P 2 . Due to the existence of dynamic disulfide bonds as well as hydrogen bonds in both P 2 and P 4 , these thermoset resins show repeatable self-healing behavior stimulated by UV irradiation. Furthermore, the polyurethane P 4 exhibits ultrahigh temperature resistance performance, with Td5 = 375 °C and Td10 = 1000 °C according to TGA curve. This work is expected to expand research and potential applications of the renewable resource eugenol in preparation of smart materials.
KeywordsEugenol Thiol-ene Self-healing polymer High temperature resistance
The work was financially supported by Natural Science Foundations of China (NO. 21564004 and 21264008) and Research Fund for Educational Commission of Jiangxi Province of China (No. GJJ150823).