Production Of Bio-based Polymers Research Articles

Electroreduction of divanillin to polyvanillin in an electrochemical flow reactor

The electrochemical conversion of biobased intermediates offers an attractive and sustainable process for the production of green chemicals. One promising synthesis route is the production of the total vanillin-based polymer polyvanillin, which can be produced by electrochemical pinacolization of divanillin (5–5´bisvanillyl). Divanillin can be easily enzymatically generated from vanillin, a renewable intermediate accessible from lignin on an industrial scale. This study investigates systematically the electrochemical production of polyvanillin in a divided plane parallel flow reactor in recirculation mode. Several analytic methods, such as online UV–VIS spectroscopy, size exclusion chromatography (SEC), 2D-NMR (HSQC, 13C/1H), TGA and DSC were used to monitor the reaction progress and to characterize the reaction products under different galvanostatic reaction conditions revealing new insights into the reaction mechanism and structural features of the polymer. Further, by using an electrochemical engineering-based approach determining the limiting current densities, we readily achieved high current densities over 50 mA cm−2 for the polyvanillin synthesis and reached averaged molecular weights up to Mw = 4100 g mol−1 and Mn = 2700 g mol−1. The cathodic polymerization to polyvanillin offers an innovative approach for the electrochemical production of biobased polymers presented on flow cell level.Graphical

Recent advances in catalytic and non-catalytic epoxidation of terpenes: a pathway to bio-based polymers from waste biomass.

Epoxides derived from waste biomass are a promising avenue for the production of bio-based polymers, including polyamides, polyesters, polyurethanes, and polycarbonates. This review article explores recent efforts to develop both catalytic and non-catalytic processes for the epoxidation of terpene, employing a variety of oxidizing agents and techniques for process intensification. Experimental investigations into the epoxidation of limonene have shown that these methods can be extended to other terpenes. To optimize the epoxidation of bio-based terpene, there is a need to develop continuous processes that address limitations in mass and heat transfer. This review discusses flow chemistry and innovative reactor designs as part of a multi-scale approach aimed at industrial transformation. These methods facilitate continuous processing, improve mixing, and either eliminate or reduce the need for solvents by enhancing heat transfer capabilities. Overall, the objective of this review is to contribute to the development of commercially viable processes for producing bio-based epoxides from waste biomass.

Biobased Polymer Synthesis from Vanillin in an Electrochemical Flow Reactor

The development of new synthesis routes for the production of biobased polymers is an urgent matter in the context of climate change. One possible promising key intermediate is vanillin (4-hydroxy-3-methoxybenzaldehyde), as it is one of a few aromatic biobased compounds, which is already available on an industrial scale. Vanillin can be produced sustainably with potential yields of up to 7% from lignin, a side product in the paper and pulp industry with amounts of over 107 tons per year. Therefore, much effort was spent from the scientific community for the preparation of a broad range of new vanillin-based polymers [1].One attractive synthesis route is the electrochemical reductive production of polyvanillin, a total vanillin-based polymer. Polyvanillin is synthesized by electrochemical pinacolization of divanillin (5-5´bisvanillyl), which is easily available by enzymatic conversion of vanillin with horseradish peroxidase and hydrogen peroxide (Scheme 1). Recent studies from others [2] as well as from our working group [3] showed the feasibility of this synthesis route and investigated the impact of electrochemical reaction parameters in batch cells.As a next step, we here transferred the electrochemical reduction of divanillin to polyvanillin from an electrochemical batch reactor into a divided plan parallel flow reactor in recycle mode. The reductive conversion of the aldehyde groups was monitored by an on-line UV-Vis setup and the molecular weight increase was followed by size exclusion chromatography. Further, 2D-NMR (HSQC, 1H/13C) was used to identify structural features of the produced polyvanillin samples. The impacts of different electrochemical impact parameters, such as applied charge, current density, flow velocity and concentration were investigated. Current densities of over 50 mA cm-2 were readily achievable and weight-averaged molecular weights up to 4300 g mol-1 were reached.This study shows an innovative electrochemical approach for the synthesis of new biobased polymers in an electrochemical flow reactor offering a total green process.

Copolymerization of palm oil with sulfur using inverse vulcanization to boost the palm oil industry

Nowadays, most of the world’s palm oil is being produced in Malaysia and Indonesia; however, the demand for this vegetable oil as an edible oil is declining in many countries since consuming palm oil in excess can result in serious health problems. Consequently, finding new applications such as the production of bio-based polymers to make use of this cheap and abundant vegetable oil seems necessary. Herein, we report the copolymerization of palm oil with sulfur with different feed ratios via inverse vulcanization. The copolymers are then characterized using Fourier-transform infrared spectroscopy, differential scanning calorimetry and X-ray diffraction analysis. The results confirmed the formation of the polymers and their stability against depolymerization. Altogether, the obtained sulfur-palm oil copolymers showed great properties such as thermal stability up to 230°C under a nitrogen atmosphere and rubbery properties at room temperature. Although the Thermogravimetric analysis (TGA) thermograms had previously confirmed the high conversion of elemental sulfur into the polymeric structure by comparing the initial sulfur content and the final polysulfide content in the polymer, some unreacted elemental sulfur was also observed in the final product. Sulfur-palm oil (S-Palm oil) is a new green polymer that helps to find a new use for palm oil as a big industry as well as sulfur which is underutilized and left in stockpile as a byproduct in gas and petroleum refineries.

Recent Advances in Renewable Polymer Production from Lignin-Derived Aldehydes.

Lignin directly derived from lignocellulosic biomass has been named a promising source of platform chemicals for the production of bio-based polymers. This review discusses potentially relevant routes to produce renewable aromatic aldehydes (e.g., syringaldehyde and vanillin) from lignin feedstocks (pre-isolated lignin or lignocellulose) that are used to synthesize a range of bio-based polymers. To do this, the processes to make aromatic aldehydes from lignin with their highest available yields are first presented. After that, the routes from such aldehydes to different polymers are explored. Challenges and perspectives of the production the lignin-derived renewable chemicals and polymers are also highlighted.

Preparation of flame retardant polyurethane foam from crude glycerol based liquefaction of wheat straw

Both wheat straw and crude glycerol are low-cost renewable feedstocks which could be promising for the production of biobased polymers. In this study, biopolyols were first prepared through liquefaction of wheat straw in crude glycerol. Effects of reaction temperature, catalyst loading, reaction time, biomass loading, and fatty acid amount on the liquefaction of wheat straw were investigated and the synthesized biopolyols were characterized. With 10 % wheat straw loading and 6% sodium hydroxide as the catalyst at 240 °C for 4 h, 89 % of what straw conversion yield can be reached. The synthesized biopolyols had a hydroxyl number of 612 mg KOH/g and an acid number of 1.3 mg KOH/g. The flame retardant PU foams were then prepared from the biopolyols and isocyanate in the presence of 25 % flame retardants including dimethyl methylphosphonate (DMMP) and expandable graphite (EG). When the mass ratio of DMMP to EG was 2:1, the limiting oxygen index value of PU foams reached 26.2 %, and vertical burning tests showed that flame-retardant PU foams can pass the V-0 rating. Fire behavior results indicated that the incorporation of DMMP and EG into the biobased PU foams can effectively reduce the smoke release and improve the smoke suppression performance, and the peak heat release rate and the peak smoke production release of the flame-retardant PU foam decreased by 40.0 % and 25.0 % compared with neat PU foam, respectively. Meanwhile, the compressive strength and the thermal conductivity of the flame-retardant PU foam were 283 kPa and 0.0295 W m−1 K−1, respectively. These results showed that the bio-based PU foam has great potential as flame retardant insulation material. This study provides a novel method for the production of flame-retardant PU foams through liquefaction of wheat straw in crude glycerol.

Production of Sustainable and Biodegradable Polymers from Agricultural Waste.

Agro-wastes are derived from diverse sources including grape pomace, tomato pomace, pineapple, orange, and lemon peels, sugarcane bagasse, rice husks, wheat straw, and palm oil fibers, among other affordable and commonly available materials. The carbon-rich precursors are used in the production bio-based polymers through microbial, biopolymer blending, and chemical methods. The Food and Agriculture Organization (FAO) estimates that 20–30% of fruits and vegetables are discarded as waste during post-harvest handling. The development of bio-based polymers is essential, considering the scale of global environmental pollution that is directly linked to the production of synthetic plastics such as polypropylene (PP) and polyethylene (PET). Globally, 400 million tons of synthetic plastics are produced each year, and less than 9% are recycled. The optical, mechanical, and chemical properties such as ultraviolet (UV) absorbance, tensile strength, and water permeability are influenced by the synthetic route. The production of bio-based polymers from renewable sources and microbial synthesis are scalable, facile, and pose a minimal impact on the environment compared to chemical synthesis methods that rely on alkali and acid treatment or co-polymer blending. Despite the development of advanced synthetic methods and the application of biofilms in smart/intelligent food packaging, construction, exclusion nets, and medicine, commercial production is limited by cost, the economics of production, useful life, and biodegradation concerns, and the availability of adequate agro-wastes. New and cost-effective production techniques are critical to facilitate the commercial production of bio-based polymers and the replacement of synthetic polymers.

Biocatalytic production of 2,5-furandicarboxylic acid: recent advances and future perspectives.

2,5-Furandicarboxylic acid (FDCA) is attracting increasing attention because of its potential applications as a sustainable substitute to petroleum-derived terephthalic acid for the production of bio-based polymers, such as poly(ethylene 2,5-furandicarboxylate) (PEF). Many catalytic methods have been developed for the synthesis of FDCA, including chemocatalysis, biocatalysis, photocatalysis, and electrocatalysis. Biocatalysis is a promising approach with advantages that include mild reaction condition, lower cost, higher selectivity, and environment amity. However, the biocatalytic production of FDCA has hardly been reviewed. To fully understand the current research developments, this review comprehensively considers the research progress on toxic effects and biodegradation of furan aldehydes, and then summarizes the latest achievements concerning the synthesis of FDCA from 5-hydroxymethylfurfural and other chemicals, such as 2-furoic acid and 5-methoxymethylfurfural. Our primary focus is on biocatalytic methods, including enzymatic catalysis (in vitro) and whole-cell catalysis (in vivo). Furthermore, future research directions and general developmental trends for more efficient biocatalytic production of FDCA are also proposed.

A Retro-biosynthesis-Based Route to Generate Pinene-Derived Polyesters.

Significantly increased production of biobased polymers is a prerequisite to replace petroleum‐based materials towards reaching a circular bioeconomy. However, many renewable building blocks from wood and other plant material are not directly amenable for polymerization, due to their inert backbones and/or lack of functional group compatibility with the desired polymerization type. Based on a retro‐biosynthetic analysis of polyesters, a chemoenzymatic route from (−)‐α‐pinene towards a verbanone‐based lactone, which is further used in ring‐opening polymerization, is presented. Generated pinene‐derived polyesters showed elevated degradation and glass transition temperatures, compared with poly(ϵ‐decalactone), which lacks a ring structure in its backbone. Semirational enzyme engineering of the cyclohexanone monooxygenase from Acinetobacter calcoaceticus enabled the biosynthesis of the key lactone intermediate for the targeted polyester. As a proof of principle, one enzyme variant identified from screening in a microtiter plate was used in biocatalytic upscaling, which afforded the bicyclic lactone in 39 % conversion in shake flask scale reactions.

Evolutionary freedom in the regulation of the conserved itaconate cluster by Ria1 in related Ustilaginaceae

BackgroundItaconate is getting growing biotechnological significance, due to its use as a platform compound for the production of bio-based polymers, chemicals, and novel fuels. Currently, Aspergillus terreus is used for its industrial production. The Ustilaginaceae family of smut fungi, especially Ustilago maydis, has gained biotechnological interest, due to its ability to naturally produce this dicarboxylic acid. The unicellular, non-filamentous growth form makes these fungi promising alternative candidates for itaconate production. Itaconate production was also observed in other Ustilaginaceae species such as U. cynodontis, U. xerochloae, and U. vetiveriae. The investigated species and strains varied in a range of 0–8 g L−1 itaconate. The genes responsible for itaconate biosynthesis are not known for these strains and therefore not characterized to explain this variability.ResultsItaconate production of 13 strains from 7 species known as itaconate producers among the family Ustilaginaceae were further characterized. The sequences of the gene cluster for itaconate synthesis were analyzed by a complete genome sequencing and comparison to the annotated itaconate cluster of U. maydis. Additionally, the phylogenetic relationship and inter-species transferability of the itaconate cluster transcription factor Ria1 was investigated in detail. Doing so, itaconate production could be activated or enhanced by overexpression of Ria1 originating from a related species, showing their narrow phylogenetic relatedness.ConclusionItaconate production by Ustilaginaceae species can be considerably increased by changing gene cluster regulation by overexpression of the Ria1 protein, thus contributing to the industrial application of these fungi for the biotechnological production of this valuable biomass derived chemical.

Carbon Support Surface Effects in the Gold-Catalyzed Oxidation of 5-Hydroxymethylfurfural.

Oxidation of 5-hydroxymethylfurfural into 2,5-furandicarboxylic acid is an important transformation for the production of bio-based polymers. Carbon-supported gold catalysts hold great promise for this transformation. Here we demonstrate that the activity, selectivity, and stability of the carbon-supported gold nanoparticles in the oxidation of 5-hydroxymethylfurfural strongly depend on the surface properties of the carbon support. Gold nanoparticles supported on basic carbon materials with a low density of functional groups demonstrate higher activity in 5-hydroxymethylfurfural oxidation (TOFAu up to 1195 h–1), higher selectivity to 2,5-furandicarboxylic acid, and better stability in comparison to gold nanoparticles supported on carbon materials with acidic surface groups. Surface groups of basic carbon supports that are positively charged under the reaction conditions result in a higher adsorption and local concentration of hydroxyl ions, which act as cocatalysts for gold and enhance gold-catalyzed dehydrogenation. Negatively charged surface groups of acidic carbons repel hydroxyls and the intermediate monoacid anions, which leads to lower reaction rates and a high selectivity toward 2,5-hydroxymethylfurancarboxylic acid. Understanding the role of support surface charge and local hydroxyl anion concentration provides a basis for the rational design of the optimal carbon support surface chemistry for highly active, selective, and stable catalysts for the oxidation of 5-hydroxymethylfurfural and related reactions.

Synthesis and characterizations of sustainable polyester polyols from non-edible vegetable oils: Thermal and structural evaluation

Vegetable oils are extensively used as a renewable raw material for the synthesis of polymers. These oils are transformed into polyol by different techniques. Among these, glycerolysis is an eco-friendly and widely used method for the production of polyol. In this process, solvent free glycerolysis of two non-edible vegetable oils, such as Chaulmoogra oil (C-Oil) and Alexandrian Laurel seed oil (A-Oil) was performed. An environment-friendly heterogeneous base catalyst, CaO was used for the transesterification reaction. The physico-chemical properties of the oils and bio-polyols (C-Polyol and A-Polyol), such as hydroxyl number, acid number, and density were determined. The hydroxyl value was found to be 189 and 200 mg KOH/g for C-polyol and A-Polyol, respectively. The acid number of the oils was reduced after the glycerolysis. The formation of polyols was confirmed by Fourier Transform Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance spectroscopy (1H and 13CNMR), and Gel Permeation Chromatography (GPC). Thermal characteristics of vegetable oils and the synthesized bio-polyol were assessed by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA). It was found that the synthesized polyols can be used for the production of biobased polymers, explicitly polyurethanes, polyesters, and epoxy.

Structure-Based Enzyme Tailoring of 5-Hydroxymethylfurfural Oxidase

5-Hydroxymethylfurfural oxidase (HMFO) is a flavin-dependent enzyme that catalyzes the oxidation of many aldehydes, primary alcohols, and thiols. The three-step conversion of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid is relevant for the industrial production of biobased polymers. The remarkable wide substrate scope of HMFO contrasts with the enzyme’s precision in positioning the substrate to perform catalysis. We have solved the crystal structure of HMFO at 1.6 A resolution, which guided mutagenesis experiments to probe the role of the active-site residues in catalysis. Mutations targeting two active-site residues generated engineered forms of HMFO with promising catalytic features, namely enantioselective activities on secondary alcohols and improved 2,5-furandicarboxylic acid yields.

Lipase-catalyzed synthesis of oligoesters of 2,5-furandicarboxylic acid with aliphatic diols

Abstract 2,5-Furandicarboxylic acid is a platform chemical for the production of biobased polymers and materials. This study reports the synthesis of furan oligoesters via polytransesterification of dimethyl furan-2,5-dicarboxylate and linear α, ω-aliphatic diols with chain length ranging from C2 to C12, using immobilized lipase B from Candida antarctica (Novozym 435) in dry organic solvents. Dimethyl furan-2,5-dicarboxylic acid (A) and 1,4-butanediol (B) were used as model substrates under different conditions producing a mixture of cyclic (CEOs) and linear (LEOs) ester oligomers up to decamers and dodecamers, respectively, with high yield. The size of the oligomers and distribution of the products is controlled by the initial concentration of substrates and temperature. While the shortest CEOs are the main cyclic compounds at 20 mM, the longest CEOs are formed at 175 mM. The chain length of the aliphatic diol co-monomers strongly influences the yield and the type of oligoesters formed. High substrate conversion of 90–95 % was obtained for C4–C12 diols, while in the case of ethylene glycol and 1,3-propanediol the conversion was moderate (i.e., 75 %). The product of the reaction between dimethyl furan-2,5-dicarboxylate and ethylene glycol (C2) and 1,3-propanediol (C3), respectively, consisted only of linear oligoesters. Longer oligoesters were obtained for alkyl chains higher than C4. The chain length and the abundance of oligoesters increases in the order: C2<C12<C10<C3<C8<C4 <C6. No substrate or product inhibition was observed in the production of furan-based oligoesters. The present biobased oligoesters are obtained via a green process and have potential application as macromonomers.