Self-healing high-performance thermosets utilizing furan/maleimide Diels–Alder, epoxy/amine nucleophilic ring-opening, and maleimide/amine Michael reactions

Abstract

The epoxy/amine nucleophilic ring-opening reaction of furfurylamine (FA) with diglycidyl ether of bisphenol A (DGEBA) at a molar ratio of 1/1 generated a polyaddition oligomer (FADGEBA). Mixtures of FADGEBA, 4,4-bismaleimidodiphenylmethane (BMI), and melamine (ML) at FADGEBA(as a repeating unit)/BMI/ ML molar ratios of 2/4/1, 4/5/1, 6/6/1, and 2/1/0 were prepolymerized at 110 °C and hot-pressed at 110-130 °C to produce cured products (FADGBA-BMI-ML-241, -451, -661, and -210). Fourier transform infrared (FT-IR) spectroscopy revealed the occurrence of the maleimide/amine Michael addition of BMI/ML and the furan/ maleimide Diels-Alder (DA) reaction of FADGEBA/BMI. The onset temperatures of the endothermal retro DA reaction for FADGBA-BMI-MLs were ~ 150 °C. The 5% mass loss temperature of FADGEBA-BMI-ML-241 at 347 °C was significantly higher than those of the other cured products. The flexural strengths and flexural strains at break of FADGBA-BMI-MLs increased in the order of FADGEBA-BMI-ML-241 < FADGEBA-BMI-ML-451 < FADGEBA-BMI-ML-661 < FADGEBA-BMI-ML-210, whereas the flexural moduli decreased in the same order. All cured products showed healing properties when hot-pressed at 160 °C/5 MPa. The healing efficiencies on flexural strength were 57-82%.

Mechanical properties and reprocessability ofDiels‐Alder‐based reversible networks from furan‐modified resins

“…First of all, we notice that the synthesized DAN samples exhibit better mechanical properties when compared to those reported in the literature for other Diels‐Alder resins. As an example, the flexural modulus of virgin samples is in the same range of that of DA systems proposed by Yasuda et al (3–4 GPa), but the samples possess higher flexural strength (80–100 MPa vs. ~25 MPa) and elongation at break (~4% vs. <1%) 13 . Concerning the effect of the formulation, Figure 7 indicates that DAN100 exhibits the higher flexural modulus and strength.…”

“…As an example, the flexural modulus of virgin samples is in the same range of that of DA systems proposed by Yasuda et al (3)(4)), but the samples possess higher flexural strength (80-100 MPa vs. ~25 MPa) and elongation at break (~4% vs. <1%). 13 Concerning the effect of the formulation, Figure 7 indicates that DAN100 exhibits the higher flexural modulus and strength. The effect of the increase of the FTP content, indeed, is a gradual decrease of both mechanical parameters.…”

“…12 Recently, to improve thermal, mechanical, and healing properties of their resin, Shibata and co-workers combined the DA reaction between a furan-functionalized precursor and a bismaleimide crosslinker with the Michael addition reaction between bismaleimide and melamine. 13 They found that mechanical properties and their preservation over different reprocessing cycles strongly depend on the DA network formulation. More in general, all these works point out the crucial role played by the nature of the crosslinked network in the balance of thermo-reversible feature of the resin and its mechanical and thermal response.…”

“…Alternatively, Zolghadr et al, proposed a semi‐interpenetrated polymer network, in which an epoxy network made of DGEBA crosslinked with DDM is blended with a Diels‐Alder poly‐adduct obtained from a furan‐functionalized resin reacted with bismaleimide 12 . Recently, to improve thermal, mechanical, and healing properties of their resin, Shibata and co‐workers combined the DA reaction between a furan‐functionalized precursor and a bismaleimide crosslinker with the Michael addition reaction between bismaleimide and melamine 13 . They found that mechanical properties and their preservation over different reprocessing cycles strongly depend on the DA network formulation.…”

High-Performance Reversible Furan–Maleimide Resins Based on Furfuryl Glycidyl Ether and Bismaleimides

“…They found that with the rise in the content of the flexible structure, the glass transition temperature decreased while the r-DA reaction temperature increased. Currently, most of the furan–maleimide resins reported in the literature have flexural strengths below 50 MPa [ 22 , 23 ]. The introduction of flexible chains is a common method to improve the mechanical properties of resins [ 24 ].…”