High-performance bio-based thermosetting resins based on bismaleimide and allyl-etherified eugenol derivatives

Abstract

In this study, eugenol (EG) and bieugenol (BEG) were reacted with allyl bromide in the presence of sodium hydroxide to produce allyl-etherified EG and BEG (AEG and ABEG), respectively. The AEG and ABEG were prepolymerized with 4,4′-bismaleimidodiphenylmethane (BMI) at 160–200 °C and then compression-molded at 250 °C for 5 h to produce cured AEG/BMI (EB) and ABEG/BMI (BB) resins with allyl/maleimide unit ratios of 1/1, 1/2 and 1/3. FT-IR analysis of the cured resins showed that the original allyl and maleimide groups were almost completely consumed during the process and that hydroxy groups were newly formed upon polymerization. Pyrolysis of AEG and ABEG revealed the hydroxy group formation to be caused by the Claisen rearrangement of AEG and out-of-ring Claisen rearrangement of ABEG. Both types of cured resins showed superior glass transition temperatures and 5% weight loss temperatures higher than 350 °C and 450 °C, which are much higher than those of already reported EG/BMI and BEG/BMI cured resins with the same allyl/maleimide ratios. The flexural moduli (2.6–3.1 GPa) of the cured resins were also higher than those of the already reported materials (0.78–2.8 GPa).