Vanilin

The DOPO compound, specifically 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, was acquired from Chemos GmbH in Altdorf, Germany. Prior to its utilization, it underwent a fresh dehydration. Vanilin, phenylphosphonic dichloride, 4-aminophenol, N-methyl-2-pyrrolidone (NMP), triethylamine (Et₃N), 4,4′-diaminodiphenylsulfone (DDS) and AgNO₃ were provided by Sigma-Aldrich (St. Louis, MO, USA) and used without further purification. The bisphenol A diglycidyl ether-based epoxy resin, having the epoxy equivalent weight (EEW) of 0.53 equiv. per 100 g (Mn ~ 377 g/mol), was acquired from Sigma-Aldrich. Bis(4-formyl-2-metoxyphenyl) phenylphosphonate was prepared via a condensation reaction of vanillin with phenylphosphonic dichloride, as described in the literature [51 (link)].

All reagents, sodium hydroxide, chloroacetic acid, sulfuric acid, toluene, heptane, acetonitril, 1-methylimidazole, chloromethyloctyl ether, Dowex Monosphere 550A, formic acid, propionic acid, trimethylacetic acid, benzene sulfonic acid, 4-phenylsulfonic acid and phenol compounds (thymol, carvacrol, eugenol, vanilin) were obtained from Sigma-Aldrich, Poznań, Poland.

Ferulic acid, vanilic acid, vanilin, ρ-coumaric acid, syrangaldehyde, 4-hydroxybenzoic acid (4HBA), Furfural, 5-hydroxymethyl furfural (HMF), tannin and tetracycline, ampicillin, erythromycin were purchased from Sigma Chemicals. Yeast extract and peptone were obtained from Oxoid Ltd (Thermo Fisher Biochemical, Beijing, China). Other chemicals and laboratory media of analytical grade were purchased from Sangon Biological Engineering Technology and Services Co. Ltd (Shanghai, China).
The corn fiber (passed through 30–40 mesh screens) was purchased from Shandong Yanggu Shengda corn cob granule Co. Ltd (Shandong, China). The bagasse fiber was donated from Guangzhou Sugarcane Industry Research Institute (Guangdong, China).