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•Effect of soybean oil/vanillin-based polymers morphology on biosensor parameters.•Usage of positron annihilation lifetime spectroscopy and electrochemical approaches.•Dependence of ...sensor characteristics on polymer chemical composition.•Possibility to adapt the biosensor to parameters according to the needs of analysis.
Network properties on local free volume and biosensor parameters of polymers based on acrylated epoxidized soybean oil (AESO), a combination of AESO with vanillin dimethacrylate (VDM) in ratio 1:0.25 mol, and its combination with vanillin diacrylate (VDA) with the same molar ratio, used as laccase-holding matrixes for the construction of amperometric biosensors, were tested and compared. The formed polymer matrixes were investigated using Positron Annihilation Lifetime Spectroscopy (PALS) as bulk samples and applying electrochemical methods as sensor films. PALS results showed that the lifetime of the ortho-positronium component and corresponding intensity are almost similar for both polymers, indicating no significant difference from the point of view of their morphology. However, the cyclic voltammetric and chronoamperometric analysis demonstrated significant differences in the bioelecrodes’ operational parameters formed by the AESO:VDM polymer compared to AESO:VDA. The AESO:VDA-based bioelectodes were characterized with a twice higher affinity toward ABTS (KMapp = 0.158 ± 0.022 mM vs. 0.326 ± 0.043 mM). At the same time, their sensitivity was about twice less compared to AESO:VDM-based (902 A·M−1·m−2vs. 1608 A·M−1·m−2), and a start concentration of the linear frame was 7-folds higher (14 μM vs. 2 μM ABTS). It was shown early, that the operational parameters of amperometric biosensors are greatly dependent on morphological characteristics of polymer matrixes (e.g., crosslink density, cavities size, thermal expansion of free-volume hole, etc.). The matrix morphology affects on efficacity of physical diffusion of the substrate to the enzyme, and electroactive product toward the electrode, as well as provides a comfortable environment for the incorporated enzyme. Here, we describe the usage of polymer matrixes with the same morphological properties but different chemical compositions, analyzing the effect of chemical structure on the operational parameters of biosensors. Thus, it was demonstrated that the sensor operational parameters depend not only on the morphological properties of the polymer holding matrixes, providing enzyme fixation and substrate/product diffusion, but also on their chemical composition, which opens a possibility to adapt the biosensor characteristics according to the required needs of analysis.
Reasonable design of non-noble metal catalysts with hollow open structure for hydrodeoxygenation (HDO) of lignin derivatives to value-added chemicals is of great significance but challenging. Herein, ...a novel MOF-derived multilayer hollow sphere coated nickel‑tungsten bimetallic catalyst (Ni2-WOx@CN-700) was fabricated via by confined pyrolysis strategy using bimetallic MOFs as a self-sacrificial template, which exhibits robust activity for the typical model HDO of vanillin to 2-methoxy-4-methylphenol (Yield of 100 % at 140 °C for no less than 10 cycles). The characterizations revealed that WOx facilitated the dispersion of Ni nanoparticles and adjusted the acidic capacity of the catalyst through the formed Ni-WOx heterojunction. Density functional theory (DFT) calculations confirms that WOx species enhanced the electron-rich nature of the active sites, while the adsorption energies of H2 and vanillin on Ni-WOx decreased from −0.572 eV and − 0.622 eV on Ni to −3.969 eV and − 4.922 eV, respectively. These results further indicated that the high activity of Ni2-WOx@CN-700 was attributed to the Ni-WOx heterojunction. Based on the characterizations and the thermodynamic calculations, the reaction mechanism was proposed. In addition, the catalyst shows good substrate universality, which enables its good commercial application prospect.
•WOx boosted hollow Ni nanoreactors catalyst was constructed form NiW-MOF precursor.•Ni-WOx heterojunction structure enabled the catalyst excellent performance.•Outstanding versatility and stability make it to be a potential industrial application catalyst.
•Aromatic aldehyde reductases exist intensively in microorganisms.•Vanillin is converted to both vanillic acid and vanillyl alcohol in R. opacus PD630.•Pd630_LPD03722 is the main vanillin reductase ...in R. opacus PD630.•Muconic acid production is improved by switching the metabolic fluxes of vanillin.•Muconic acid yield of 97.83% is realized with vanillin as the substrate.
Vanillin bioconversion is important for the biological lignin valorization. In this study, the obscure vanillin metabolic distribution in Rhodoccous opacus PD630 was deciphered by combining the strategies of intermediate detection, putative gene prediction, and target gene verification. The results suggest that approximately 10% (mol/mol) of consumed vanillin is converted to vanillic acid for further metabolism, and a large amount is converted to dead-end vanillyl alcohol in R. opacus PD630. Subsequently, five vanillin reductases were identified in R. opacus PD630, among which Pd630_LPD03722 product exhibited the greatest activity. With the detected metabolic distributions of vanillin, the conversion of vanillin to muconic acid was facilitated by deleting domestic vanillin reductase genes and introducing vanillin dehydrogenase from Sphingobium sp. SYK-6. Ultimately, the muconic acid yield from vanillin increased to 97.83% (mol/mol) from the initial 10% (mol/mol). Moreover, this study demonstrated the existence of vanillin reductases in Escherichia coli, Bacillus subtilis, and Corynebacterium glutamicum.
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•Various lignins and model compounds were oxidized to produce vanillin.•The structure changes of lignin during the nitrobenzene oxidation were investigated.•The interunit linkages of ...the lignin significantly affected the vanillin yield.•A high vanillin yield was obtained from the lignins with a high β-O-4 content.
Lignin is the renewable source of aromatics in nature, and the conversion of lignin into vanillin is very attractive. However, the vanillin yield is closely related to the resource of lignin and its isolation process, and relatively low yield of vanillin is always obtained from lignin. In order to improve the vanillin yield from lignin, in this work, the relationship between lignin linkages and vanillin yield was explored. Five lignins (kraft lignin, alkali lignin, lignosulfonate, and two enzymatic lignins) and various lignin model compounds (monomers, dimers, and polymers) were characterized by NMR spectroscopy and oxidized to prepare vanillin. Results indicated that the interunit linkages of the lignin had a significant influence on the vanillin yield. The more β-O-4 linkages in lignin, the higher yield of corresponding aldehydes was obtained. It is believed that the vanillin yield can be significantly improved by using lignins with high content of β-O-4 linkages.
Nowadays, the synthesis of (semi)aromatic polymers from lignin derivatives is of major interest, as aromatic compounds are key intermediates in the manufacture of polymers and lignin is the main ...source of aromatic biobased substrates. Phenols with a variety of chemical structures can be obtained from lignin deconstruction; among them, vanillin and ferulic acid are the main ones. Depending on the phenol substrates, different chemical modifications and polymerization pathways are developed, leading to (semi)aromatic polymers covering a wide range of thermomechanical properties. This review discusses the synthesis and properties of thermosets (vinyl ester resins, cyanate ester, epoxy, and benzoxazine resins) and thermoplastic polymers (polyesters, polyanhydrides, Schiff base polymers, polyacetals, polyoxalates, polycarbonates, acrylate polymers) prepared from vanillin, ferulic acid, guaiacol, syringaldehyde, or 4‐hydroxybenzoic acid.
This review presents the major interests of lignin derivatives such as vanillin, ferulic acid, guaiacol, syringaldehyde, and 4‐hydroxybenzoic acid as a source of novel semi‐aromatic biobased polymers. The structure–property relationships of these materials are discussed.
Epoxy resins possess poor flame retardancy and have difficulty in both recycling and reprocess ability which largely limit their application. Herein, two vanillin-based epoxy monomers, shorted as ...VAD-EP and VDP-EP, containing both imine bonds and inherently fire retarding phosphorus elements, were synthesized via in situ condensation reaction with DDM and addition reaction with DOPO, followed by the epoxidation by epichlorohydrin. Epoxy vitrimer materials were then cured by D230 diamine hardener by adjusting the proportion of VAD-EP and VDP-EP monomer. When the mass ratio of VAD-EP and VDP-EP was 8:2, A8P2-D230 reached the fire retarding UL-94 V0 rating and LOI value of 27.0% with only 0.66% of phosphorus content, this behavior was ascribed to condensed phase and free radical scavenging mechanisms. When the mass ratio was 7:3, the tensile strength and elastic modulus of the A7P3-D230 epoxy were 75.5 MPa and 2.5 GPa, respectively, i.e. 48.6% and 18.8% higher than A10P0-D230 sample. Meanwhile, the material showed high stress relaxation rate, due to the presence of dynamic imine bonds in the topological crosslinking network. As a consequence, the epoxy vitrimer exhibited excellent self-healing capability, reprocessability and degradation behaviors. The biobased epoxy vitrimer was then used to prepare the carbon fibers (CFs) reinforced epoxy composites, results showed that CFs can be completely recycled. Interestingly, the recycled CFs maintain unchanged chemical structure, mechanical properties and morphology as the original CFs.
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The investigation of biobased systems as photocurable resins for optical 3D printing has attracted great attention in recent years; therefore, novel vanillin acrylate-based resins were designed and ...investigated. Cross-linked polymers were prepared by radical photopolymerization of vanillin derivatives (vanillin dimethacrylate and vanillin diacrylate) using ethyl(2,4,6-trimethylbenzoyl)phenylphosphinate as photoinitiator. The changes of rheological properties were examined during the curing with ultraviolet/visible irradiation to detect the influences of solvent, photoinitiator, and vanillin derivative on cross-linking rate and network formation. Vanillin diacrylate-based polymers had higher values of yield of insoluble fraction, thermal stability, and better mechanical properties in comparison to vanillin dimethacrylate-based polymers. Moreover, the vanillin diacrylate polymer film showed a significant antimicrobial effect, only a bit weaker than that of chitosan film. Thermal and mechanical properties of vanillin acrylate-based polymers were comparable with those of commercial petroleum-derived materials used in optical 3D printing. Also, vanillin diacrylate proved to be well-suited for optical printing as was demonstrated by employing direct laser writing 3D lithography and microtransfer molding techniques.
Electrochemical oxidation of vanillin (VAN) in the presence of caffeine (CAF) was studied on a gold (Au) electrode modified with 3‐amino‐1,2,4‐triazole‐5‐thiol (ATT) film by using differential pulse ...voltammetry (DPV) and cyclic voltammetry (CV) method. The formation of the ATT film on the Au electrode surface was characterized by the CV, fourier transform infrared spectroscopy (FTIR) and impedance spectroscopy (EIS) methods. A single irreversible oxidation peak of the VAN was obtained by using the CV method. The determination of VAN in the presence of CAF was carried out at pH 4 in Britton Robinson buffer (BR) by the DPV method. Under the optimal conditions, the oxidation peak current was proportional to the concentration of VAN in the range of 1.1 μM to 76.4 μM in the presence of CAF with the correlation coefficient of 0.997 and the detection limit of 0.19 μM (S/N=3). The selective determination of VAN in a commercial coffee sample was carried out with satisfactory results on the ATT‐Au modified electrode.
The poor impact toughness and flame retardant performance have greatly restricted the engineering application of epoxy thermoset. To obtain the high-performance epoxy composites, the renewable ...vanillin-based flame retardant toughening agent (PVSi) was synthesized and incorporated into epoxy. The use of PVSi macromolecules can significantly enhance the impact toughness of epoxy. With 5 wt% of PVSi, the impact strength of the epoxy was maximally raised by 189.69%, from 12.42 kJ/m2 of the neat EP to 35.98 kJ/m2 of EP/PVSi5 composites. The toughening effect of PVSi macromolecules on epoxy was closely linked to its structural features, such as the flexible phenylsiloxane, active imine and polar phosphaphenanthrene groups. Simultaneously, the EP/PVSi5 composites reached up to the V-0 rating in vertical burning test (UL-94) and 29.5% in limiting oxygen index (LOI), with only 0.27 wt% ultra-low phosphorus loading. Additionally, the suppressed heat release, the evidently reduced toxic pyrolytic volatiles, and the promoted charring capability of EP/PVSi composites can be obtained, with phosphaphenanthrene, phenylsiloxane and diaminodiphenylsulfone groups in PVSi macromolecules jointly playing a role. These results indicated the improved fire safety of epoxy. Furthermore, the free radical scavenging effect of P· and PO·, the fuel dilution effect of nonflammable NH3 and SO2, the catalytic charring effect of the pyrophosphoric acid and metaphosphoric acid, the charring-stability effect of phenylsiloxane group and the suppression effect of high-quality carbon layers were analyzed and summarized. It was expected that PVSi would pave the way for the development of more highly efficient flame retardant toughening agents and high-performance epoxy thermoset.
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•A novel renewable polymeric flame retardant toughening agent PVSi was synthesized.•Multiple flame retardant elements are contained in PVSi.•PVSi obviously improves the fire safety of EP with ultra-low phosphorus loading.•PVSi significantly improves the impact toughness of EP.•The mechanisms of flame retardancy.
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Pancake-like TiO2 (M-TiO2) derived from the metal-organic framework was inlaid into three-dimensional flower-like BiOI through a facile solvothermal method. M-TiO2 supplies large ...surface area and mesoporous structure for attachment and transfer of the substrates and products, while BiOI acts as a photosensitizer to absorb visible light and generates electrons and holes. The distinct structure of M-TiO2/BiOI gives a favorable contact between the two monomers, and promotes the transfer of charge carriers. In conjunction with the proper band positions of M-TiO2 and BiOI, the efficient separation of electron-hole pairs is attained. Benefiting from the above cooperative effects of M-TiO2 and BiOI, the performance for the vanillin generation from sodium lignosulfonate (SLS) over M-TiO2/BiOI composites has a prominent improvement under visible light. Specifically, the yield over optimal M-TiO2/BiOI sample is about 5.8 mg/gSLS, obviously superior to that over pristine M-TiO2 (~1 mg/gSLS) and BiOI (~1.1 mg/gSLS). It is found that h+ and O2– play the key role for vanillin generation from sodium lignosulfonate, and the low vanillin generation under UV–vis light sheds light on that OH is an adverse factor. We hoped that this work could inspire the studies on the photocatalytic valorization of biomass using noble metal-free catalysts.
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