Aromatic polymers are known for their thermal stability as well as their good mechanical properties, but most of these polymers are synthesised from fossil resources. Vanillin is one of the few aromatic chemicals that is currently commercially produced from biomass and can be derivatised to make it suitable for polycondensation reactions. In this work a vanillin-derived bio-based diol was synthesised exploiting the potential of more benign reagents to replace toxic dimethylformamide. The resulting monomer was utilised in a series of enzymatic polycondensation reactions with different diesters including dimethyl succinate (DMSu), dimethyl adipate and dimethyl sebacate (DMSe), and the aromatic monomers diethyl terephthalate diethyl isophthalate diethyl pyridine-2,5-dicarboxylate (PD25) and diethyl pyridine-2,4-dicarboxylate (PD24) using a lipase to produce semi-aromatic polyesters. The molecular weight of the resulting polyesters increased as the chain length of the diester decreased, with a number average molecular weight of 21.8 kDa for polyesters achieved based on the dimethyl succinate (using diphenyl ether (DPE) as the organic media). For semi-aromatic diesters, para-substituted monomers yielded higher molecular weight polymers compared to the corresponding meta-substituted structure. Several different green solvents were also investigated to carry out this reaction with anisole that resulted to be a good alternative to diphenyl ether with similar number average molecular weights obtained at certain conditions.

Polar aprotic solvents have many applications in organic chemistry, but there are few bio-based substitutes available. As legislation becomes more restrictive due to health and safety concerns, the need for safer and more sustainable solvents has become ever more pressing. Here, we have built on previous works to synthesise several derivatives of the cellulose-derived Cyrene through an environmentally friendly ketalisation reaction, resulting in a class of solvents called the Cygnets. Diol reagents were selected based on their bio-based origin, and four novel solvent structures were synthesised and comprehensively characterised using NMR, ( 1 H and 13 C), GC-FID, and HPLC-ESI-MS. The solvents were also shown to be non-toxic to skin cell lines HaCaT and BJ-5ta, presenting a viability above 70%. Finally, the presented structures show differing properties depending on the structure of the secondary ring formed. The presence of longer side chains results in a solvent with a lower boiling point, allowing it to be used in a wider range of reactions, and presents the interesting possibility to tune the final properties by modifying the used diol reagent.

Aligning with the objectives of the EU chemicals strategy for sustainability, an ultrarapid, safe and sustainable method for producing a library of levoglucosenone (LGO)-based amphiphilic molecules was developed. LGO and a series of alkyl malonates were employed as renewable building blocks to synthesize a series of structurally diverse adducts via Michael addition. The use of a nontoxic, inexpensive heterogeneous base catalyst (Ca(OH)2) enables the reaction to proceed through base activation of the Michael donors, namely the series of malonates employed. This process generates the carbon-based nucleophiles, the enolates, in situ. These intermediates subsequently react with levoglucosenone, the Michael acceptor, via a 1,4-conjugate addition. The microwave-enhanced procedure provides a rapid, selective and energy-efficient heating source, enabling a solventless and low-impact process. Reaction conditions were optimized through a multivariate Design of Experiments (D-optimal) approach, affording reproducible gravimetric yields above 80% with high selectivity and stereochemical control. The configuration of the newly formed chiral center was confirmed by X-ray characterization of the dimethyl derivative. The physical properties of the four synthesized adducts were investigated through an integrated set of methods, including theoretical tools such as the hydrophilic-lipophilic balance calculations and COnductor like Screening MOdel for Real Solvents simulations. n-Octanol/water partition coefficients, contact angle measurements, and emulsion tests further revealed the potential of these molecules as wetting and emulsifying agents. Overall, the results highlight how it is possible to synthesize LGO-based adducts with clear and tunable structure-property features using an ultrarapid, solventless protocol.

Biochar is a renewable carbon material with tunable surface properties that make it a promising support for enzyme immobilization. In this study, bamboo-derived biochars produced at 300, 400, 500, and 600 °C were evaluated as supports for the immobilization of Candida antarctica lipase B (CaLB) and applied to the enzymatic polycondensation of dimethyl adipate and 1,8-octanediol. The effect of pyrolysis temperature on biochar properties was investigated by elemental analysis, infrared spectroscopy, and Brunauer–Emmett–Teller (BET) surface area analysis. Increasing the pyrolysis temperature promoted carbonization, aromatization, and pore development, leading to a marked increase in surface area and CaLB immobilization efficiency. However, higher enzyme loading did not result in better catalytic performance. The biochar produced at 400 °C (B400) showed the best overall performance, producing the highest polyester number-average molecular weight (Mn ≈ 11 kDa) while achieving approximately 97% monomer conversion. In addition, B400 exhibited the highest operational stability over five consecutive reaction cycles. The improved performance was attributed to its balanced combination of surface chemistry, accessible porosity, and enzyme-support interactions, which favored enzyme immobilization while preserving catalytic accessibility. This work highlights that tailoring biochar properties through controlled pyrolysis provides an effective strategy for developing renewable and low-cost alternatives to conventional petroleum-derived supports for enzymatic polymerization.

The work focuses on the design of sustainable materials that meet key environmental requirements, including the bio-based origin of starting compounds, environmentally friendly preparation methods, as well as easy recyclability and biodegradation at the end of life. To this end, systems based on reagents from renewable sources, such as epoxidized soybean oil acrylate (ESOA) and cystamine (Cys) as a crosslinker, were developed to form covalent adaptable networks (CANs), using a simple reaction carried out under mild conditions, without the need for solvent or catalyst. Two different molar ratios between the acrylate groups of ESOA and the amino groups of Cys were investigated (1:1, ESOA-Cys_1:1 and 2:1, ESOA-Cys_2:1). The Aza–Michael reaction between the two components was confirmed and monitored during curing at different temperatures by IR spectroscopy, revealing distinct kinetic behaviors for the two formulations, a phenomenon attributed to a change in the reaction mechanism. In both cases, network formation was confirmed by gel fraction (GF

The main goal of this work was to develop an environmentally friendly method for upcycling poly (lactic acid) (PLA) into functionalized oligomers, as well as to propose an innovative strategy enabling their direct use within the reaction environment. To this end, the investigated reaction-an alcoholysis based on the use of reagents derived from renewable sources-was carried out in the green solvent dihydrolevoglucosenone (Cyrene (R), Cy). Indeed, upon the addition of virgin polymer, a PLA/oligomer mixture was obtained, providing a suitable system for the direct preparation of porous films. Specifically, the alcoholysis process, carried out using pentaerythritol (PE) as the polyalcohol and zinc stearate as the catalyst was optimized by monitoring the viscosity of the reaction mixture overtime. 1H NMR analysis of the resulting oligomers confirmed a decrease in molecular weight and the formation of a branched structure, attributed to the multifunctionality of the polyalcohol and dependent on the amount of PE added. These structural characteristics significantly affected the thermal behaviour of the oligomers, as demonstrated by DSC and TGA analyses. Porous films, prepared via the Non-solvent Induced Phase Separation (NIPS) technique using the reaction mixture directly as the casting solution, exhibited a leaflike structure that was unaffected by the presence of oligomers in the mixture, as observed by FE-SEM analysis. The enzymatic hydrolysability and retention capacity were evaluated using Humicola insolens cutinase (HiC) as the enzyme and pararosaniline hydrochloride (PARA) as a cationic organic dye, selected to mimic the behavior of amino-terminated drugs. The results indicated that, compared to neat PLA films, those incorporating the developed oligomers exhibited enhanced dye retention capacity and faster degradation rate. These phenomena were attributed to the high functionality of the branched additives obtained through the alcoholysis process. Finally, a closed-loop process for Cy recovery through distillation was established, enabling its reuse and improving the overall sustainability of the process.

Correction for ‘Flow bioprocessing of citrus glycosides for high-value aglycone preparation’ by Agostina Colacicco et al. , Catal. Sci. Technol. , 2023, 13 , 4348–4352, https://doi.org/10.1039/d3cy00603d.

This work presents an eco-friendly and easily scalable process to modify the surface of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH) films, a bioplastic of relevant application interest, making them magnetically active while preserving the intrinsic properties of the polymer. To achieve this, similar to 10 nm spinel iron oxide magnetic nanoparticles (MNPs), synthesized via coprecipitation method, were assembled using Layer-by-Layer (LbL) deposition with two bio-sourced polyelectrolytes: DNA (polyanion) and chitosan (polycation). An aminolysis reaction was employed to strengthen the interactions between the polymer substrate and the first coating layer. Additionally, the optimal reaction time was determined to maximize surface amine functionalization while minimizing film degradation. The effectiveness of the deposition was demonstrated by both the linear growth of the LbL assembly on a model silicon substrate using FT-IR measurements and by studying the morphology of the coated PHBH films through FE-SEM. These latter measurements showed the formation of a uniform coating after the deposition of 10 bilayers (BL). The 10 BL coated films demonstrated efficient magnetic separation from a mixed polymer waste scraps under a static applied magnetic field. Moreover, these materials undergo enzymatic degradation, with the MNPs that could be easily recovered from the enzymatic solution via magnetic separation, enabling their potential reuse. The proposed approach offers an alternative strategy aimed at tackling the issue of plastic contamination and material sorting during recycling.

This work details the synthesis of 2,4:3,5-di-O-methylene-d-glucitol (glux-diol), a bicyclic acetal derivative of d-glucose obtained from d-glucono-1,5-lactone, and also explores its subsequent polymerization to produce biobased polyesters. Key steps for the synthesis of glux-diol are (i) protection with paraformaldehyde, (ii) Fischer esterification, and (iii) reduction with lithium aluminum hydride (LiAlH4). A new purification method was developed to effectively remove inorganic salt byproducts, which can hinder polymerization. The sugar-based monomer was then copolymerized with C4-C10 dimethyl esters using Candida antarctica lipase B as a biocatalyst in Cygnet 2.0, a green, high-boiling solvent. The biocatalytic polycondensation produced oligomers with number-average molecular weights (M n) between 900 and 2200 g mol-1. These materials exhibited thermal stabilities ranging from 391 to 419 °C, with the specific temperature depending on the molecular weight, degree of polymerization, and the carbon chain length of the chosen diester. Overall, this integrated approach, which combines efficient sugar functionalization with biocatalysis, offers a promising pathway for the synthesis of novel biobased polyesters.

Despite its many advantages over other bioplastics, poly(epsilon-caprolactone) (PCL) still faces limited applications and a lack of sustainable chemical recycling routes that could extend its life cycle, reduce its carbon footprint, and enhance its applicability. In this work, to address this gap, a novel bulk alcoholysis process was developed for upcycling PCL into functional hydroxyl-terminated oligomers using two bio-based fatty alcohols, 1-dodecanol and 1,12-dodecandiol, in the presence of zinc stearate as a catalyst. This approach enables precise control over the final properties of the resulting oligomers by varying the type and the concentration of the alcohol, yielding mono-and difunctional telechelic structures suitable for further synthesis. The prepared PCL-based oligomers were used directly, without purification, as macroinitiators for the ring-opening polymerization (ROP) of L-lactide to synthesize well-defined diblock (PCL-PLA) and triblock (PLA-PCL-PLA) copolymers with a PCL/PLA ratio of 1 and tailored chain lengths. These copolymers were then applied in two different scenarios. The diblock copolymers were tested as compatibilizers for PLA/PCL blends, where they enhanced the elongation at break by improving interfacial adhesion between the two polymer phases. Moreover, two telechelic systems, namely a PCL oligomer and a PLA-PCL-PLA copolymer, were used in the preparation of thermoplastic polyurethanes (TPUs) via chain-extension reactions with methylene diphenyl diisocyanate (MDI), leveraging the residual catalyst and demonstrating efficient polymerization. Overall, the developed approach provides a robust, solvent-free, scalable, and effective strategy for valorizing PCL waste, establishing a platform for producing sustainable, functional polyester-based building blocks.

Carbohydrates are among the most abundant biopolymers in the world and offer a promising source for the synthesis of value-added chemicals. Galactaric acid is an attractive bio-based building block that has not yet been fully exploited. Currently, regulatory, sustainability, safety-by-design and performance requirements for polymer additives are becoming increasingly strict. As a result, innovation in this field must be accelerated to develop new materials with enhanced properties. With this objective, new sugar-based plasticizers based on galactaric acid have been synthesised. Poly(lactic acid) (PLA) was selected as a brittle, bio-based polymer, to evaluate the ability of these additives to improve its mechanical properties. The best additive led to an increase of the elongation at break up to 260% when compared to the starting PLA. Experimental results have been supported by computational studies and show how small modifications in the molecular structure can influence both the synthesis and the performance of these additives.

The sustainable production of polymerizable aromatic monomers from renewable feedstocks is a key challenge toward reducing the reliance of the polymer industry on fossil resources. Herein, we report a biocatalytic platform for the efficient conversion of lignin-derived hydroxycinnamic acids into hydroxystyrene monomers suitable for further functionalization and polymer synthesis. A cofactor-independent ferulic acid decarboxylase from Bacillus pumilus (BpFDC) catalyzed the decarboxylation of ferulic, p-coumaric, caffeic, and sinapinic acids under mild conditions, affording the corresponding hydroxystyrenes in moderate to excellent yields. To improve catalyst recovery and process sustainability, the enzyme was covalently immobilized on superparamagnetic nanoparticles, enabling straightforward magnetic separation and reuse while maintaining catalytic activity over multiple cycles. Process intensification through a green anisole/buffer biphasic system significantly enhanced substrate loading and productivity, increasing the space–time yield from 0.54 to 7.4 g L-1 h-1 while facilitating product isolation and solvent recycling. The obtained 4-vinylguaiacol was subsequently functionalized via O-(hydroxyethyl)ation using bio-derived ethylene carbonate as a benign alkylating agent, affording a renewable bifunctional monomer suitable for further polymerization or post-polymerization modifications. Overall, this chemo-enzymatic strategy combines renewable feedstocks, recyclable biocatalysts, green reaction media, and waste-minimizing process design to provide a sustainable route toward functional bio-based styrene-derived building blocks for advanced polymeric materials.

The transition toward sustainable alternatives in polymeric material production is a critical step in reducing the environmental impact of the traditional plastic industry. In this work, a novel synthetic pathway for the synthesis of poly(caprolactone) (PCL) was developed combining three present day sustainable technologies: enzymatic catalysis, biomass-derived solvents, and flow processing. The ring-opening polymerization (ROP) of epsilon-caprolactone was catalyzed by Candida antarctica lipase B (CaLB). The reaction conditions were first optimized in batch mode by tuning the amount of used monomer, initiator (0%-10%) and evaluating different reaction solvents (anisole, eucalyptol, 2,2,5,5-tetramethyltetrahydrofuran, phenetole and 2-methyltetrahydrofuran). The best batch conditions (no initiator and phenetole as solvent) yielding PCL with Mn up to similar to 8000 g mol-1 were successfully translated to flow systems where the reaction time was dramatically reduced from 24 h to 5 min while maintaining comparable Mn value (7800 g mol-1). These findings demonstrate the potential of integrating biocatalysis, renewable solvents, and flow technology for the development of scalable, eco-friendly processes paving the way for future innovations in sustainable polymer synthesis.

The enzymatic polymerization of biomass-derived polyphenols presents a sustainable approach to producing advanced materials. However, the structural diversity and incomplete characterization of tannins pose challenges to optimizing the process. This study investigates how tannin composition and the presence of phenolic and non-phenolic compounds in aqueous Pinus radiata bark extracts influence laccase-catalyzed polymerization and the resulting material’s thermal and structural properties. The extracts were characterized using proximate and ultimate analysis, Py-GC/MS, FT-IR, TGA, and phenol content analysis before polymerization with Myceliophthora thermophila laccase (MtL). Structural and thermal analysis of the polymers revealed significant transformations driven by enzymatic oxidation. Tannin extracts rich in resorcinol and low in carbohydrates and less polar compounds produced highly cross-linked polymers with exceptional thermal stability, retaining 86% residual mass at 550°C. These findings demonstrate that tannin composition plays a key role in polymerization efficiency and material performance. The resulting thermally stable polymers offer potential applications in flame retardancy and sustainable material development, providing a promising pathway for biomass valorization.

The increasing drug consumption worldwide raises environmental and health concerns, as pharmaceutical residues entering the environment pose risks to both ecosystems and human health. Enzyme remediation has been emerging in recent decades as a possible solution to eliminate recalcitrant pharmaceutical pollutants in wastewater or contaminated sites, offering a faster alternative to microbial remediation, e.g., without the need for microbial growth or adaptation. Moreover, enzymes operate under a wider range of conditions, avoiding biomass formation and disposal, and antibiotic resistance risks. In the present study, high amounts (up to 5000 mg/L) of trazodone hydrochloride and its by-products, namely Impurity H and Compound F, were enzymatically treated using a laccase-mediator system consisting of the laccase from Trametes hirsuta (ThL) and the mediator 1-hydroxybenzotriazole (HBT). Different concentrations of an organic solvent system composed of acetone and isobutyl alcohol in a 1:1 ratio and up to 20% (v/v) were employed to simulate the matrix of a real industrial production waste stream. Thereby, the enzymatic oxidation of trazodone hydrochloride and its by-products was not significantly affected by the varying solvent concentrations, resulting in maximum conversions of 62%, 73% and 62% of trazodone hydrochloride, impurity H, and impurity F, respectively. Liquid chromatography—high-resolution mass spectrometry (LC-HRMS) indicated preferential oxidation of the piperazine group in all three molecules. In vivo ecotoxicity experiments must be carried out in the future to assess the toxicological and environmental behaviour of the obtained degradation products. This work emphasised the potential role of enzymes in supporting the transition towards a more sustainable pharmaceutical industry.

This study investigates the synthesis of alpha,omega-dienes derived from levoglucosenone (LGO) and their polymerization via Acyclic Diene Metathesis (ADMET) polymerization, with a focus on sustainability and efficiency. The monomers were prepared using two approaches: Steglich and lipase-catalyzed esterification. While the chemical method achieved higher yields, the enzymatic route provided a more environmentally friendly alternative. ADMET polymerization was then applied for the first time to LGO-derived monomers using six different ruthenium-based catalysts, leading to high conversion rates and LGO-based polyesters with molecular weights (M n) of up to 6 kDa. Thermal analysis showed glass-transition temperatures (T g) ranging from -39 to -7 degrees C, depending on the monomer, while thermogravimetric analysis (TGA) demonstrated T d5% above 300 degrees C. To assess the environmental impact of different polymerization methods reported to produce LGO polyesters, this study also benchmarked the results against polyesters from (1R,2S,4S,5R)-6,8-dioxabicyclo[3.2.1]octane-2,4-diol (HO-LGOL)-the precursor to the alpha,omega-dienes-using both metal- and enzyme-catalyzed polycondensations. Among all the methods tested, solvent-free ADMET polymerization showed the lowest E-factors (0.019-0.026 kg waste/kg polymer), whereas solution-based ADMET and enzymatic polymerization generated significantly more waste due to solvent consumption. Metal-catalyzed polycondensation resulted in moderate waste levels but required higher temperatures (160-220 degrees C), leading to increased energy consumption. The qualitative analysis of energy efficiency further highlighted ADMET polymerization as a greener approach, requiring only 30 min at 80 degrees C, in contrast to the longer reaction times needed for metal- and enzyme-catalyzed polymerizations. Overall, this study demonstrates that ADMET polymerization offers a promising and greener route for polyester synthesis from levoglucosenone, balancing reaction efficiency, environmental impact, and polymer properties.

Biobased polyesters are gaining increasing interest as sustainable replacements for traditional fossil-based polymers. The compound (1R,2S,5R)-6,8-dioxabicyclo[3.2.1]octane-2,4-diol (HO-LGOL) is a cellulose-derived monomer that can be used to synthesize polyesters with properties similar to those obtained with classical reagents. In this work, several HO-LGOL-based copolymers were sustainably synthesized in the green solvent dioxolane Cygnet (0.0) (referred to as "Cygnet 2") utilizing Candida antarctica Lipase B (CaLB) as a biocatalyst. HO-LGOL was reacted with dimethyl adipate and aliphatic diols of various lengths. Different ratios of reactants were also investigated, and an equimolar amount of HO-LGOL and aliphatic diol was found to yield copolymers with the highest level of HO-LGOL incorporation. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF) confirmed the structure of end groups and the presence of HO-LGOL in longer polymer chains. The incorporation of HO-LGOL resulted in terpolymers with an HO-LGOL content of up to 49% (relative to the aliphatic diol), which exhibited lower crystallinity and higher thermal stability compared to the corresponding aliphatic homopolymers.

Microwave irradiation is demonstrated as a screening method for the polymerization of crude terephthalic acid (TA) and crude bis(2-hydroxyethyl) terephthalate (BHET), obtained from the enzymatic hydrolysis and glycolysis of poly(ethylene terephthalate) (PET). The use of microwave irradiation and a reduced pressure of 40 mbar allows for the preparation of medium-long PET with measured Mw values up to 30-40 kg/mol relative to PMMA standards in less than 1 h. The versatility of the screening approach is demonstrated through the evaluation of a range of esterification and polycondensation catalysts using pristine starting materials. It was found that for the reaction between TA and EG using a Ti(OBu)4 catalyst, it yields the largest polymers, accompanied by minimal coloration. For the polymerization of BHET, the Sb2O3 catalyst produced large polymers with little coloration, while the use of the Ti(OBu)4 catalyst gives highly colored materials. The developed procedure is used to re-polymerize crude TA recovered from enzymatic degradation of PET waste as well as crude BHET recovered from glycolysis of pristine and waste PET. Repolymerization is possible, but the color and molecular weight of the final polymer are found to depend on the type and amount of impurities in the starting materials. The relevance of the formed intermediates as precursors for high molar mass PET was confirmed through solid-state polymerization that yielded high molar mass PET from selected samples.

This study investigates the generation of hydroxyl radicals ((OH)-O-center dot) using the biochar-packed column flow system for methylene blue (MB) degradation in the presence of oxygen. Electron paramagnetic resonance (EPR) was employed to quantify and analyse the stability of carbon-centred permanent free radicals (PFRs) in the solid state (1017-1019 spins per g). In water, PFRs act as catalysts for the generation of hydroxyl radicals ((OH)-O-center dot), which are responsible for the advanced oxidation process (AOP) of organic molecules. Bamboo-based activated carbons (BACs) were produced through fast pyrolysis at various temperatures ranging from 300 to 800 degrees C, with the gas environment switched from N2 to CO2. The BAC treated at 400 degrees C (B400), which balanced physicochemical properties (lower surface area, larger micropore volume, and higher formation of reactive oxygen species in water), demonstrated the highest performance in removing MB compared to B500 and B600. The efficiency of MB removal depended on the presence of (OH)-O-center dot in aerated or purged solutions, and the crucial role of dissolved oxygen in the formation of (OH)-O-center dot was established. Additionally, the study explores the kinetics of MB removal, emphasising the predominance of chemical mechanisms such as electron transfer reactions and PFR-mediated oxidative degradation. This work provides valuable insights into the potential application of BACs for environmental remediation, particularly in treating dye-contaminated wastewater, eliminating the need to add H2O2 as a chemical source of reactive oxygen species (ROS) in solution.