Biobased Divanillin As a Precursor for Formulating Biobased Epoxy Resin

Abstract

Divanillin (DV), which can be facilely synthesized via vanillin dimerization, was employed as a building block to formulate epoxy resin. DV was synthesized through a novel approach in hot water in only 30 min with a yield of 87.5%. The process involved FeSO4-catalyzed Na2S2O8-based oxidative coupling of vanillin without any purification, followed by treatment with biobased epichlorohydrin. Epoxidized-divanillin (EDV) was cured with the petroleum-based, commercially available hardener isophorone diamine (IPDA) and a biobased-diamine (GX-3090). Complete curing of the mixture was confirmed by Fourier transform infrared (FTIR) spectroscopy and statistical heat resistant-indices (Ts), which indicated the formation of cross-linked networks with a thermostability similar to materials prepared with diglycidyl ether bisphenol A (DGEBA, the commercial BPA-based resin). The epoxy resin developed with this new formulation had comparable storage moduli (1.7–2.3 GPa) and similar glass transition temperatures as commercial resins. The epoxy networks exhibited good solvent resistance, while the presence of aldehyde groups in EDV yielded in more readily cleavable ester and amide bonds during the cross-linking process, yielding a resin with improved degradation under acidic conditions. Almost 40% of the segments in networks cured with EDV/IPDA were solubilized in acetone after treatment with 1 M HCl at room temperature in 24 h.

Choosing the Right Lignin to Fully Replace Bisphenol A in Epoxy Resin Formulation

“…Epoxy contents of epoxidized lignin samples were measured by 1 H NMR according to a previously reported method [64] . Each epoxidized lignin sample (ca.…”

Recent development on bio‐based thermosetting resins

“…38 Under the catalysis of Na 2 S 2 O 8 , two equivalent vanillin can also be coupled directly and the aldehyde group could be retained. 39 Jian and Weng et al developed a trifunctional bio-based epoxy resin bearing triazine structure through the conversion of aldehydes to cyan and cyclization (Scheme 4(B)). After curing by 4,4 0 -diaminodiphenyl sulfone, the thermosets showed excellent T g (300 C) and considerable mechanical properties (53.9% and 14.3% higher respectively) compared to the DGEBA counterpart.…”

“…68 By Michael addition, three amines were integrated into acrylic epoxy soybean oil, which can be used for simply regulating the properties of polymers. 69 In addition, utilizing the curing system with amine derivatives containing aliphatic ring, 39 hetero ring, 21 and aromatic ring, 67 could improve the performance of mixture.…”

Recent Advances in Renewable Polymer Production from Lignin-Derived Aldehydes

“…Divanillin is readily made via enzymatic oxidative dimerization of vanillin on horseradish peroxidase ( Armoracia rusticana ) [ 78 ]. Alternatively, it can be produced oxidative coupling by using laccase [ 79 , 80 , 81 ], iron(III) chloride [ 82 ], and persulfate salts [ 83 , 84 , 85 ]. For instance, Fang et al has very recently showed that sodium persulfate (Na 2 S 2 O 8 ) is an effective persulfate salt for the synthesis of divanillin due to its high water solubility and inexpensiveness [ 85 ].…”

“…Bisphenols are precursors of a wide variety of polymers including polyesters [ 79 ], polycyanurates [ 72 ], polycarbonates [ 72 ], and epoxy resins [ 85 , 94 ] that are made through simple modifications of the structure of bisphenols. Two strategies have been available to make bisphenols from vanillin.…”