Biobased Benzoxazine Derived from Daidzein and Furfurylamine: Microwave‐Assisted Synthesis and Thermal Properties Investigation

Abstract

A biobased benzoxazine resin (Dz-f) demonstrating excellent thermal properties was synthesized from daidzein and furfurylamine by using a microwave heating method. The chemical structure of synthesized benzoxazine monomer was identified by FTIR and NMR ( H and C NMR) before it was cured and its thermal properties evaluated by differential scanning calorimetry (DSC), TGA, and dynamic mechanical analysis (DMA). The cured resin p(Dz-f) exhibited a glass transition temperature (T ) of 391 °C, a very high char yield of 68.7 %, and outstanding thermal stability; the T value obtained was the highest thermal stability value ever reported for polybenzoxazine with a high biobased content. Moreover, Dz-f demonstrated a satisfying processability, which was rare for the high-performance thermosetting resins. This work provided us with a new strategy for the preparation of high biocontent resins with excellent thermal properties. In addition, the combination of biobased feedstocks with a microwave-assisted heating method as well as the potential application of this approach in high-end fields might perpetuate remarkable progress towards the sustainable development of the polymeric industry.

Review on the Accelerated and Low-Temperature Polymerization of Benzoxazine Resins: Addition Polymerizable Sustainable Polymers

“…To reduce the carbon foot print, exploration of non-petrochemical feedstocks that are obtained naturally or in bio-wastes is actively sought both as solvent or solvent-free reactions [84]. These include cardanol (C) [85][86][87][88][89][90]; guaiacol (G) [89,91,92]; eugenol [93,94]; isoeugenol [95]; vanillin (V) [96][97][98]; umbelliferone (U) [99]; catechol [100]; cinnamic, ferulic, coumaric [101,102] and phloretic acid [101,103,104]; magnolol [105]; resveratrol [106]; humic acid (coal origin) [107]; daidzein [108]; naringenin [109]; arbutin-linked phenol [110]; levulinic acid based diphenolic acid [111,112]; sesamol [113]; apigenin [84] and amines such as stearylamine [93], dopamine [114], furfuryl amine (fa) [95,115], aminolysed poly(ethylene terephthalate) [116] and isomannide diamine (ima) [89], as shown in Figure 3. They exhibit the potential to compete with the existing petro-based high performance thermosets [117].…”

Synthesis of Highly Thermally Stable Daidzein-Based Main-Chain-Type Benzoxazine Resins

“…Besides, both daidzein-based benzoxazines show an additional exothermic peak at around 260 °C, including another exothermic reaction occurring after the ring-opening polymerization of oxazine rings. These additional exothermic peaks partially overlapped with the exotherm of ring-opening polymerization of oxazine ring, which can be interpreted by the polymerization of the carbon–carbon double bond in the daidzein structure [26].…”

“…Notably, each daidzein compound has two phenolic hydroxyls, making it an appropriate phenolic resource for synthesizing various thermosetting resins. Daidzein-based epoxy and benzoxazine resins have been recently synthesized, and the properties of the resulting thermosets have also been evaluated [25,26]. The daidzein-based epoxy resins exhibited excellent flame-retardant performance with a flammability rating of V-0 in the UL94 test [25].…”

“…The daidzein-based epoxy resins exhibited excellent flame-retardant performance with a flammability rating of V-0 in the UL94 test [25]. In addition, a daidzein-based benzoxazine was also prepared, which showed very high thermal stability with a glass transition temperature as high as 391 °C [26].…”

Synthesis and characterization of bio‐based benzoxazines derived from thymol

“…These types of phenolic compounds are plant‐derived and widely found in variety of plants. Although several plant‐derived phenolic compounds were utilized, to the best of our knowledge, thymol has not been used as a phenolic derivative for the synthesis of the benzoxazine resins. Therefore, thymol is a white crystalline compound found in thyme and other various plants was used in this study to produce bio‐benzoxazine resins …”