Smart, Sustainable, and Ecofriendly Chemical Design of Fully Bio‐Based Thermally Stable Thermosets Based on Benzoxazine Chemistry

Abstract

What inspired you for the cover image? Perhapst he analogy with as pace travel across the universe where no matter the direction there are always new amazing 'things' to be discovered, letting us know and appreciate deeper what we have in hand. Af ew years ago, only very few examples of naturally based benzoxazines were known.T hat was the early stages of aj our-ney that today may be seen as the development of an ovel full topic, biomass-based benzoxazinesa nd polybenzoxazines. Nowadays, new materials based on natural renewable raw materials are investigated, studied, formulated, and applied. Those early 'launches' helpedt o'launch' this novel yet established field within the benzoxazines'a rena, represented in the cover as the 'Green Galaxyo fBenzoxazines'. What is in your opinion an upcoming research theme likely to becomeo ne of the 'hot topics' in the near future? It is hard to make futurology in this sense because there are so many different and equally relevant fields, each of them with their respective subdisciplines. Nevertheless, what we can envisage is that regardless what the upcomingh ot topic or topics might be, they will certainly have to involve the right tools to efficientlyd esign and develop novel materials exploiting good chemistry based on renewable natural resources and sustainability.T his last concept applies not only to the materials themselves but also to their raw materials and methodolo-gies used. Invited for this month'sc over are the groups at the

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

“…As shown in Figure 5, there was as harp endothermic peak that appeared at 164 8Cd uring the scan (black line), which was undoubtedly caused by the melting of Dz-f and this very sharp peak indicated its high-purity.Inaddition, the less high melting point of 164 8Cm ight endow Dz-f with good processability, which was investigated in the following part. [26,54] The exothermic enthalpy of Dz-f was approximated as 358.5 Jg À1 (88.9 kJ mol À1 ). Usually,t he peak temperaturei nt he DSC exothermic curve is taken as an indicatort oe valuate the curing reactivity.T he lower the temperature of the peak, the highert he reactivity of the system.…”

“…[15] Up to now,alarge quantity of biobased benzoxazines have already been prepared from the renewable cardanol, [16,17] diphenolic acid, [18,19] phloretic acid, [20] furfurylamine, [21,22] stearylamine, [23] coumarin, [24,25] umbelliferone, [26] and more recently the lignin derivatives (guaiacol, [27][28][29][30] vanillin, [31][32][33] and eugenol [34][35][36][37][38] ). [15] Up to now,alarge quantity of biobased benzoxazines have already been prepared from the renewable cardanol, [16,17] diphenolic acid, [18,19] phloretic acid, [20] furfurylamine, [21,22] stearylamine, [23] coumarin, [24,25] umbelliferone, [26] and more recently the lignin derivatives (guaiacol, [27][28][29][30] vanillin, [31][32][33] and eugenol [34][35][36]…”

“…Utilizing the structurald iversity of renewable monomers to prepare the biobased materials with surprisingp roperties is aw orthy expectation.D aidzein, also known as 7-hydroxy-3-(4-hydroxyphenyl)-4H-chromen-4-one, is ar enewable compound found exclusively in soybeans and other legumes. [26] Furfurylamine is another biobased product derived from av ariety of agricultural byproducts such as corncobs and wheat bran. Considering the huge annualp roduction of soybean in the world, daidzeini sa bundantly available.…”

Synthesis and properties of a novel bio‐based benzoxazine resin with excellent low‐temperature curing ability

“…So far, some sources of bio‐based phenol and amine have been used in the preparation of bio‐based benzoxazine resin, including resorcinol, hydroquinone, eugenol, vanillin, cardanol, diphenolic acid, guaiacol, cardanol, furfurylamine, stearylamine, dehydroabietylamine etc . Rao and colleagues found that the curing initiation temperature of cardanol benzoxazine was reduced to 138 °C from 230 °C with incorporation of hydroxy benzoxazoline and its activation energy reduced initially with incorporation of hydroxyl benzoxazoline and later increased with respect to the composition of monomers in the mixture .…”

“…Rao and colleagues found that the curing initiation temperature of cardanol benzoxazine was reduced to 138 °C from 230 °C with incorporation of hydroxy benzoxazoline and its activation energy reduced initially with incorporation of hydroxyl benzoxazoline and later increased with respect to the composition of monomers in the mixture . Ishida and colleagues found that the furanic moiety in the structure of furfurylamine induces a cooperative activating effect, thus lowering the polymerization temperature, and also contributes to a better thermal stability of the resulting polymers . Varma and colleagues found that the formyl group of vanillin and the furanic moiety of furfurylamine may help in curing benzoxazine at a lower temperature and increasing the char yield .…”