Progress of Polymers from Renewable Resources: Furans, Vegetable Oils, and Polysaccharides

Hydrophobic Aerogels from Vinyl Polymers Derived from Radical Polymerization: Proof-of-Concept

Hydrophilicity is one important drawback of bio-based aerogels. To overcome this issue, a novel approach for the preparation of mesoporous, water repellent aerogels is introduced, which combines synthesis of cross-linked bio-based copolymers from methacrylate copolymerizations, followed by solvent exchange and supercritical drying steps. The influence of monomers with different nonpolar ester groups (methyl, vanillin, tetrahydrofurfuryl) on textural properties and water contact angles of the dry products is assessed. Final aerogels show generally high overall porosities (≈96%), low densities (0.07-0.11 g cm-3) as well as fine, mainly mesoporous networks, and specific surface areas in the range of 120-240 m2 g-1. Hereby, choice of the methacrylate ester groups results in differences of the resulting pore-size distributions. Water repellency tests show stable static water contact angles in the hydrophobic range (≈100°) achieved for the substrate containing the vanillin ester group. On the contrary the other substrates absorb water quickly, which indicates a decisive role of the ester group. The presented approach opens up a new pathway to bio-based aerogels with intrinsic hydrophobicity. It is suggested that the properties are tailored by the choice of the monomer structure, hence enabling further adaption and optimization of the products.

Influence of steric hindrance on the 1,4- versus 1,6-Michael addition: synthesis of furans and pentasubstituted benzenes

We described the influence of steric hindrance on the 1,4- versus 1,6-Michael addition reaction on 2-(3,3-bis(methylthio)-1-arylallylidene)malononitriles. An efficient and direct synthesis of trisubstituted furans was achieved through the reaction of 2-(3,3-bis(methylthio)-1-arylallylidene)malononitriles and acetone under mild conditions in good to moderate yield by the 1,4-Michael addition. Further exploration of the reaction with a sterically hindered aryl group containing 2-(3,3-bis(methylthio)-1-arylallylidene)malononitriles afforded biaryls by an in situ generated nucleophile through the 1,6-Michael addition. The synthetic utility of furan is further explored. These precursors are easily accessible from aryl methyl ketones. Various functional groups like alkyl, aryl, nitrile, amine, aroyl, and thiomethyl can be directly installed in the benzene and furan rings. A one-pot approach for the construction of a benzene nucleus was also developed. The structure of two compounds was confirmed by X-ray crystallography.

Sterically Hindered Oleogel-Based Underwater Adhesive Enabled by Mesh-Tailoring Strategy

Underwater adhesives hold significant relevance in daily life and numerous industrial applications. Despite considerable efforts, developing scalable, high-performance underwater adhesives through a simple and effective method remains a formidable challenge. This study presents a novel mesh-tailoring strategy for in situ, rapid, and ultrastrong oleogel-based underwater adhesives (OUA), which comprises a highly crosslinked polyurethane network with a matching mesh size (≈2.22 nm) that precisely entraps bio-based epoxidized soybean oil (ESO) molecules (≈2.31 nm) by steric hindrance effect. This oleogel exhibits unprecedented robust mechanical properties (≈35 MPa) and maintains stability under extreme conditions, including high temperatures (100 °C), high pressures (30 MPa), and immersion in various solvents (water, ethanol, or ESO). In particular, this oleogel displays high hydrophobicity, rapid curing, and strong interface affinity, resulting in ultrahigh underwater adhesion strength (up to 2.13 MPa) and exceptional substrate universality. Moreover, the remarkable environmental adaptability and stability of OUA enable its use in harsh aqueous environments, including acidic/alkaline, saline, and extreme temperature solutions. The comprehensive capabilities of the OUA underscore its potential for building underwater structures, repairing leaky containers, and sealing broken submarine pipelines. This research establishes the foundation for the designing of next-generation underwater adhesives and offers fresh perspectives for exploring oleogel-based materials.

Bottom-Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis

Linear d-glucans are natural polysaccharides of simple chemical structure. They are comprised of d-glucosyl units linked by a single type of glycosidic bond. Noncovalent interactions within, and between, the d-glucan chains give rise to a broad variety of macromolecular nanostructures that can assemble into crystalline-organized materials of tunable morphology. Structure design and functionalization of d-glucans for diverse material applications largely relies on top-down processing and chemical derivatization of naturally derived starting materials. The top-down approach encounters critical limitations in efficiency, selectivity, and flexibility. Bottom-up approaches of d-glucan synthesis offer different, and often more precise, ways of polymer structure control and provide means of functional diversification widely inaccessible to top-down routes of polysaccharide material processing. Here the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for d-glucan polymerization are described and the use of applied biocatalysis for the bottom-up assembly of specific d-glucan structures is shown. Advanced material applications of the resulting polymeric products are further shown and their important role in the development of sustainable macromolecular materials in a bio-based circular economy is discussed.

Catalytic [4+2]- and [4+4]-cycloaddition using furan-fused cyclobutanone as a privileged C4 synthon

Cycloaddition reactions play a pivotal role in synthetic chemistry for the direct assembly of cyclic architectures. However, hurdles remain for extending the C4 synthon to construct diverse heterocycles via programmable [4+n]-cycloaddition. Here we report an atom-economic and modular intermolecular cycloaddition using furan-fused cyclobutanones (FCBs) as a versatile C4 synthon. In contrast to the well-documented cycloaddition of benzocyclobutenones, this is a complementary version using FCB as a C4 reagent. It involves a C-C bond activation and cycloaddition sequence, including a Rh-catalyzed enantioselective [4 + 2]-cycloaddition with imines and an Au-catalyzed diastereoselective [4 + 4]-cycloaddition with anthranils. The obtained furan-fused lactams, which are pivotal motifs that present in many natural products, bioactive molecules, and materials, are inaccessible or difficult to prepare by other methods. Preliminary antitumor activity study indicates that 6e and 6 f exhibit high anticancer potency against colon cancer cells (HCT-116, IC50 = 0.50 ± 0.05 μM) and esophageal squamous cell carcinoma cells (KYSE-520, IC50 =  0.89 ± 0.13 μM), respectively.

Acid-Catalyzed Activation and Condensation of the =C5H Bond of Furfural on Aldehydes, an Entry Point to Biobased Monomers

Furfural is an industrially relevant biobased chemical platform. Unlike classical furan, or C-alkylated furans, which have been previously described in the current literature, the =C5H bond of furfural is unreactive. As a result, on a large scale, C=C and C=O bond hydrogenation/hydrogenolysis is mainly performed, with furfuryl alcohol and methyl tetrahydrofuran being the two main downstream chemicals. Here, we show that the derivatization of the -CHO group of furfural restores the reactivity of its =C5H bond, thus permitting its double condensation on various alkyl aldehydes. Overcoming the recalcitrance of the =C5H bond of furfural has opened an access to a biobased monomer, whose potential have been investigated in the fabrication of renewably-sourced poly(silylether). By means of a combined theoretical-experimental study, a reactivity scale for furfural and its protected derivatives against carbonylated compounds has been established using an electrophilicity descriptor, a means to predict the molecular diversity and complexity this pathway may support, and also to de-risk any project related to this topic. Finally, by using performance criteria for industrial operations in the field of fuels and commodities, we discussed the industrial potential of this work in terms of cost, E-factor, reactor productivity and catalyst consumption.

Designing Degradable Polymers from Tricycloalkenes via Complete Cascade Metathesis Polymerization

Cascade metathesis polymerization has been developed as a promising method to synthesize complex but well-defined polymers from monomers containing multiple reactive functional groups. However, this approach has been limited to the monomers involving simple alkene/alkyne moieties or produced mainly non-degradable polymers. In this study, we demonstrate a complete cascade ring-opening/ring-closing metathesis polymerization (RORCMP) using various tricycloalkenes and two strategies for the efficient degradation. Through rational design of tricycloalkene monomers, the structure and reactivity relationship was explored. For example, tricycloalkenes with trans configuration in the central ring enabled faster and better selective cascade RORCMP than the corresponding cis isomers. Also, a 4-substituted cyclopentene moiety in the monomers significantly enhanced the overall cascade RORCMP performance, with the maximum turnover number (TON) reaching almost 10,000 and molecular weight up to 170 kg/mol using an amide-containing monomer. Furthermore, we achieved one-shot cascade multiple olefin metathesis polymerization using tricycloalkenes and a diacrylate, to produce new highly A,B-alternating copolymers with full degradability. Lastly, we successfully designed xylose-based tricycloalkenes to give well-defined polymers that underwent ultra-fast and complete degradation under mild conditions.

The influence of the combined impact of shear stress and cavitation on the structure and properties of starch-natural rubber composite

In this article, we examined a high-performance, environmentally friendly method for producing composite films based on starch and natural rubber latex (NR). To increase the compatibility of the components, the casting dispersions were subjected to short-term (10 s) mechanical activation in a rotor-stator device. Using the rotational viscosimetry method, it was found that mechanical activation reduces the structuring degree and the effective viscosity of the casting dispersions. The composite films with the NR content of 0-30 % were characterized using optical and SEM microscopy, X-ray diffraction, tensile, and moisture resistance testing data. When the NR content increases from 0 to 30 %, the elongation at break increased by 570 % and 950 % for films obtained using mechanical activation and without it, respectively. The extremely high increase in film tensile strength (on average by 155 %) and the decrease in the NR extractability with toluene due to the use of mechanical activation indicate the possibility of mechanically induced formation of an in situ copolymer at the starch-NR interface. The developed method can be recommended for large-scale production of composite starch-based materials.

Supramolecular Polymer Network based on Electrophilic Substitution (ES) Adduct of Furan-Triazolinedione

Polymers with furan functionality have been the subject of extensive research on developing sustainable materials applying a limited number of dynamic covalent approaches. Herein, we introduce a facile, dynamic non-covalent approach to make a furan polymer readily accessible for self-healing applications based on its electrophilic substitution (ES) with a commercially available 1,2,4-triazoline-3,5-dione (TAD) derivative, 4-phenyl-TAD (PTAD). A tailor-made furan polymer, poly(furfuryl methacrylate) (PFMA), considering it an initial illustrative example, was rapidly ES modified with PTAD to produce furfuryl-tagged triazolidine that subsequently associated via inter-molecular hydrogen (H-) bonding to produce a thermally reversible supramolecular polymer network under ambient conditions. The H-bonded network was experimentally quantified via ATR-IR analysis and theoretically rationalized via the density functional theory (DFT) study using smaller organic model compounds analogous to the macromolecular system. Thermoreversible feature of the H-bonded triazolidine-derived supramolecular polymer network enabled the solution reprocessing and self-healing of the polymer material.

From Forest to Future: Synthesis of Sustainable High Molecular Weight Polyamides Using and Investigating the AROP of β-Pinene Lactam

Polyamides (PA) are among the most essential and versatile polymers due to their outstanding characteristics, for example, high chemical resistance and temperature stability. Furthermore, nature-derived monomers can introduce hard-to-synthesize structures into the PAs for unique polymer properties. Pinene, as one of the most abundant terpenes in nature and its presumable stability-giving bicyclic structure, is therefore highly promising. This work presents simple anionic ring-opening polymerizations of β-pinene lactam (AROP) in-bulk and in solution. PAs with high molecular weights, suitable for further processing, are produced. Their good mechanical, thermal (Td s up to 440 °C), and transparent appearance render them promising high-performance biomaterials. In the following, the suitability of different initiators is discussed. Thereby, it is found that NaH is the most successful for in-bulk polymerization, with a degree of polymerization (DP) of about 322. For solution-AROP, iPrMgCl·LiCl is successfully used for the first time, achieving DPs up to about 163. The obtained PAs are also hot-pressed, and the dynamic mechanical properties are analyzed.

Bio-based hyperbranched epoxy resins: synthesis and recycling

Epoxy resins (EPs), accounting for about 70% of the thermosetting resin market, have been recognized as the most widely used thermosetting resins in the world. Nowadays, 90% of the world's EPs are obtained from the bisphenol A (BPA)-based epoxide prepolymer. However, certain limitations severely impede further applications of this advanced material, such as limited fossil-based resources, skyrocketing oil prices, nondegradability, and a "seesaw" between toughness and strength. In recent years, more and more research has been devoted to the preparation of novel epoxy materials to overcome the compromise between toughness and strength and solve plastic waste problems. Among them, the development of bio-based hyperbranched epoxy resins (HERs) is unique and attractive. Bio-based HERs synthesized from bio-derived monomers can be used as a matrix resin or a toughener resulting in partially or fully bio-based epoxy thermosets. The introduction of a hyperbranched structure can balance the strength and toughness of epoxy thermosets. Here, we especially focused on the recent progress in the development of bio-based HERs, including the monomer design, synthesis approaches, mechanical properties, degradation, and recycling strategies. In addition, we advance the challenges and perspectives to engineering application of bio-based HERs in the future. Overall, this review presents an up-to-date overview of bio-based HERs and guidance for emerging research on the sustainable development of EPs in versatile high-tech fields.

Network-supported and adaptable binding efficacy for flexible and multi-functionalized chitosan/phenolic carbaldehyde hydrogels

A thoughtful strategy has been intended to control the hydrogel networking to assess the binding efficacy of multifunctional hydrogel. The processing of two distinct network-supported hydrogels has portrayed to express the operating interactions involved during co-existence with solvents, small molecules, biomolecules, etc. Herein, chitosan has separately functionalized in semisynthetic approaches with 4-hydroxyisopthalaldehyde (ChDA) and 2-hydroxybenzene-1,3,5-tricarbaldehyde (ChTA) to construct different gel networks. The disposition of gel networks ChDA adapts more flexible chain or spine, whereas ChTA possesses restricted movements within gel networks. The gel networks of hydrogels have a significant role in their distinct physical activities. Their gel-bonding elucidations have performed to establish the variation in mechanical, swelling photophysical properties, etc. Remarkable self-fluorescence behaviors are used as a tool for binding study. Distinctive gel networks and their flexibility have investigated against self-fluorescence, UV-Vis, and FTIR against small molecule, Boron trifluoride and biomolecule, and Bovine serum albumin. Hydrogel/BF3 shows variation in fluorescence due to the disposition of gel networks. Hydrogel/BSA quenching of fluorescence at three different temperatures provides the binding constant and Stern-Volmer quenching constant. Theoretical DFT and docking studies successfully established the flexibility against binding study. The controlling of cross-linking or functionalization is very crucial for the development of hydrogel-mediated applications.

Facile fabrication of reusable starch sponge with adjustable crosslinked networks for efficient nest-trap and in situ photodegrade methylene blue

The fabrication of reusable natural polysaccharide sponges with nanoscale dispersed photocatalysts to achieve robust photocatalytic efficiency is desirable yet challenging. Herein, inspired by the nesting behavior when fishing, we designed reusable starch sponge with chemically anchored nano-ZnO into carboxylated starch matrix by thermoplastic interfacial reactions and solvent replacement for absorbing and photodegrading methylene blue (MB) in situ. The plasticization and interfacial reactions promoted a simultaneous increase in the reactivity of the starch hydroxyl/carboxyl groups and the specific surface area of ZnO. Meanwhile, the crosslinked networks of starch sponge could be adjusted by varying the ZnO and carboxylic groups contents. The results of photodegradation experiments revealed the recyclable closed-loop process of attraction-trapping-photodegradation of MB was successfully realized, achieving the effect of killing three birds with one stone. The reusable starch sponge with homogeneous dispersion of nano-ZnO by constructing three-dimensional porous channels possessed the high enrichment capacity and the remarkable photocatalysis efficiency with 150 mg/L ZnO. Under UV irradiation, the starch sponge degraded 97 % of MB with 1.67 × 10-3 min-1 photodegradation rate constant even after five cycles, which exceeded most existing photocatalytic systems. Overall, the reusable starch sponge with adjustable structure provided new insights for multifunctional bio-based photocatalyst loading systems.

Pyridyl-Isonicotinoyl Hydrazone-Bridged Zn(II) Coordination Framework with Thiophenedicarboxylato Link: Structure, Biological Activity, and Electrical Conductivity

Multidimensional applicability of functional materials is one of the focal attractions in today's scientific research. Highly stable and crystalline coordination polymers served as one of the active members in the club of multifunctional materials. Toward this concept, a 3-dimensional (3D) coordination framework, {[Zn2(tdc)2(pcih)2]n} (1) (tdc2-, 2,5-thiophene dicarboxylate; pcih, pyridine-4-carboxaldehyde isonicotinoyl hydrazine), is designed and has been structurally well characterized by single crystal X-ray crystallography. One of the carboxylate groups of tdc2- chelates to Zn(II), while the other carboxylato group (-COO) acts as bridging-O to neighboring Zn(II); the pcih serves as pyridyl-N bridging motif to two Zn(II) centers. The optical band gap, 3.83 eV (Tauc's plot), implies probable semiconducting ability of the material. Interestingly, the device fabricated using compound 1 measures the electrical conductivity, 2.21 × 10-5 S cm-1, and series resistance (Rs), 807 Ω, at the dark phase, which are improved significantly to 6.36 × 10-5 S cm-1 and 460 Ω, respectively, under illumination conditions. Isoniazid, used to synthesize pcih and hence the Zn(II) compound 1, is a medicine; so, the medicinal efficiency of 1 is checked by measuring the anticancer activity against MDA-MB-231, HeLa, HCT-116, and HepG2 cells. It is observed that drug efficacy is highest on MDA-MB-231 cells (IC50: 19.43 ± 1.36 μM) than other cancer cells [IC50: 24.43 ± 2.02 μM (HeLa), 26.06 ± 3.48 μM (HCT-116), and 44.28 ± 3.04 μM (HepG2)]. Therefore, the material has significant contribution in the area of energy and health toward the sustainable development goals.

Elevated temperature enhanced lethal and sublethal acute toxicity of polyethylene microplastic fragments in Daphnia magna

Microplastic (MP) pollution poses a growing concern in freshwater ecosystems, which are further threatened by global warming. Thus, this study investigated the effect of elevated temperature (25 °C) on acute toxicity of polyethylene MP fragments to Daphnia magna over a 48 h period. At the reference temperature (20 °C), MP fragments (41.88 ± 5.71 µm) induced over 70 times higher lethal toxicity than that induced by MP beads (44.50 ± 2.50 µm), with median effective concentrations (EC50) of 3.89 and 275.89 mg L-1, respectively. Elevated temperature significantly increased (p < 0.05) the lethal (EC50 = 1.88 mg L-1) and sublethal (lipid peroxidation and total antioxidant capacity) toxicity in D. magna exposed to MP fragments compared to those at the reference temperature. Additionally, the elevated temperature led to a significant increase (p < 0.05) in the bioconcentration of MP fragments in D. magna. Overall, the present study increases understanding for the ecological risk assessment of microplastics under global warming, highlights that elevated temperature can be seriously increased bioconcentration of MP fragments, leading to increased acute toxicity in D. magna.

A Review of Biodegradable Plastics: Chemistry, Applications, Properties, and Future Research Needs

Environmental concerns over waste plastics' effect on the environment are leading to the creation of biodegradable plastics. Biodegradable plastics may serve as a promising approach to manage the issue of environmental accumulation of plastic waste in the ocean and soil. Biodegradable plastics are the type of polymers that can be degraded by microorganisms into small molecules (e.g., H2O, CO2, and CH4). However, there are misconceptions surrounding biodegradable plastics. For example, the term "biodegradable" on product labeling can be misconstrued by the public to imply that the product will degrade under any environmental conditions. Such misleading information leads to consumer encouragement of excessive consumption of certain goods and increased littering of products labeled as "biodegradable". This review not only provides a comprehensive overview of the state-of-the-art biodegradable plastics but also clarifies the definitions and various terms associated with biodegradable plastics, including oxo-degradable plastics, enzyme-mediated plastics, and biodegradation agents. Analytical techniques and standard test methods to evaluate the biodegradability of polymeric materials in alignment with international standards are summarized. The review summarizes the properties and industrial applications of previously developed biodegradable plastics and then discusses how biomass-derived monomers can create new types of biodegradable polymers by utilizing their unique chemical properties from oxygen-containing functional groups. The terminology and methodologies covered in the paper provide a perspective on directions for the design of new biodegradable polymers that possess not only advanced performance for practical applications but also environmental benefits.

MOF Material-Derived Bimetallic Sulfide CoxNiyS for Electrocatalytic Oxidation of 5-Hydroxymethylfurfural

The electrocatalytic conversion of biomass into high-value-added chemicals is one of the effective methods of green chemistry. Conventional metal catalysts have disadvantages, such as low atomic utilization and small surface areas. Catalyst materials derived from metal-organic frameworks (MOFs) have received much attention due to their unique physicochemical properties. Here, an MOF-derived non-precious metal CoxNiyS electrocatalyst was applied to the oxidation of biomass-derivative 5-hydroxymethylfurfural (HMF). The HMF oxidation reaction activities were modulated by regulating the content of Co and Ni bimetals, showing a volcano curve with an increasing proportion of Co. When the Co:Ni ratio was 2:1, the HMF conversion rate reached 84.5%, and the yield of the main product, 2,5-furandicarboxylic acid (FDCA), was 54%. The XPS results showed that the presence of high-valent nickel species after electrolysis, which further proved the existence and reactivity of NiOOH, as well as the synergistic effect of Co and Ni promoted the conversion of HMF. Increasing the content of Ni could increase the activity of HMF electrochemical oxidation, and increasing the content of Co could reduce the increase in the anodic current. This study has important significance for designing better HMF electrochemical catalysts in the future.

Natural Polymeric Nanobiocomposites for Anti-Cancer Drug Delivery Therapeutics: A Recent Update

Cancer is one of the most common lethal diseases and the leading cause of mortality worldwide. Effective cancer treatment is a global problem, and subsequent advancements in nanomedicine are useful as substitute management for anti-cancer agents. Nanotechnology, which is gaining popularity, enables fast-expanding delivery methods in science for curing diseases in a site-specific approach, utilizing natural bioactive substances because several studies have established that natural plant-based bioactive compounds can improve the effectiveness of chemotherapy. Bioactive, in combination with nanotechnology, is an exceptionally alluring and recent development in the fight against cancer. Along with their nutritional advantages, natural bioactive chemicals may be used as chemotherapeutic medications to manage cancer. Alginate, starch, xanthan gum, pectin, guar gum, hyaluronic acid, gelatin, albumin, collagen, cellulose, chitosan, and other biopolymers have been employed successfully in the delivery of medicinal products to particular sites. Due to their biodegradability, natural polymeric nanobiocomposites have garnered much interest in developing novel anti-cancer drug delivery methods. There are several techniques to create biopolymer-based nanoparticle systems. However, these systems must be created in an affordable and environmentally sustainable way to be more readily available, selective, and less hazardous to increase treatment effectiveness. Thus, an extensive comprehension of the various facets and recent developments in natural polymeric nanobiocomposites utilized to deliver anti-cancer drugs is imperative. The present article provides an overview of the latest research and developments in natural polymeric nanobiocomposites, particularly emphasizing their applications in the controlled and targeted delivery of anti-cancer drugs.

The key role of pretreatment for the one-step and multi-step conversions of European lignocellulosic materials into furan compounds

Nowadays, an increased interest from the chemical industry towards the furanic compounds production, renewable molecules alternatives to fossil molecules, which can be transformed into a wide range of chemicals and biopolymers. These molecules are produced following hexose and pentose dehydration. In this context, lignocellulosic biomass, owing to its richness in carbohydrates, notably cellulose and hemicellulose, can be the starting material for monosaccharide supply to be converted into bio-based products. Nevertheless, processing biomass is essential to overcome the recalcitrance of biomass, cellulose crystallinity, and lignin crosslinked structure. The previous reports describe only the furanic compound production from monosaccharides, without considering the starting raw material from which they would be extracted, and without paying attention to raw material pretreatment for the furan production pathway, nor the mass balance of the whole process. Taking account of these shortcomings, this review focuses, firstly, on the conversion potential of different European abundant lignocellulosic matrices into 5-hydroxymethyl furfural and 2-furfural based on their chemical composition. The second line of discussion is focused on the many technological approaches reported so far for the conversion of feedstocks into furan intermediates for polymer technology but highlighting those adopting the minimum possible steps and with the lowest possible environmental impact. The focus of this review is to providing an updated discussion of the important issues relevant to bringing chemically furan derivatives into a market context within a green European context.

Theoretical study on the degradation mechanism, kinetics and toxicity for aqueous ozonation reaction of furan derivatives

The compounds including Furan-2,5-dicarboxylic acid (FDCA), 2-methyl-3-furoic acid (MFA), and 2-furoic acid (FA), containing Furan rings are considered to be possessing high ozone reactivity, although in depth studies of their ozonation processes have not been carried out yet. Hence, mechanism, kinetics and toxicity by quantum chemical, and their structure activity relationship are being investigated in this study. Studies of reaction mechanisms revealed that during the ozonolysis of three furan derivatives containing C=C double bond, furan ring opening occurs. At temperature (298 K) and pressure of 1 atm the degradations rates of 2.22 × 10³ M^-1 s^-1 (FDCA), 5.81 × 10⁶ M^-1 s^-1 (MFA) and 1.22 × 10⁵ M^-1 s^-1 (FA) suggested that the reactivity order is: MFA > FA > FDCA. In the presence of water, oxygen and ozone, the primary product of ozonation, the Criegee intermediates (CIs) would produce lower molecule weight of aldehydes and carboxylic acids by undergoing degradation pathways. The aquatic toxicity reveals that three furan derivatives play green chemicals roles. Significantly, most of degradation products are least harmful to organisms residing the hydrosphere. The mutagenicity and developmental toxicity of FDCA is minimum as compared to FA and MFA, which shows the applicability of FDCA in a wider and broader field. Results of this study revealed its importance in the industrial sector and degradation experiments.

Polymers without Petrochemicals: Sustainable Routes to Conventional Monomers

Access to a wide range of plastic materials has been rationalized by the increased demand from growing populations and the development of high-throughput production systems. Plastic materials at low costs with reliable properties have been utilized in many everyday products. Multibillion-dollar companies are established around these plastic materials, and each polymer takes years to optimize, secure intellectual property, comply with the regulatory bodies such as the Registration, Evaluation, Authorisation and Restriction of Chemicals and the Environmental Protection Agency and develop consumer confidence. Therefore, developing a fully sustainable new plastic material with even a slightly different chemical structure is a costly and long process. Hence, the production of the common plastic materials with exactly the same chemical structures that does not require any new registration processes better reflects the reality of how to address the critical future of sustainable plastics. In this review, we have highlighted the very recent examples on the synthesis of common monomers using chemicals from sustainable feedstocks that can be used as a like-for-like substitute to prepare conventional petrochemical-free thermoplastics.

Recent advances in electrochemical deoxygenation reactions of organic compounds

As naturally abundant and recyclable industrial feedstock, alcohols and carboxylic acids have drawn tremendous attention in medicinal chemistry and polymer chemistry. The selective C-O cleavage of the hydroxyl group represents an appealing strategy to deliver alkyl and carbonyl moieties into organic molecules. Classical examples of hydroxyl activation include the Appel reaction, Mitsunobu reaction, and Barton-McCombie deoxygenation. However, these early approaches still require large amounts of oxidants or reductants, and suffer from harsh conditions and low atom economy. Electrosynthesis has proven to be an effective and mild way of the modern chemical industry, avoiding the use of chemical oxidants/reductants through the action of an electric current. In this review, we have summarized the recent advances in electrochemical deoxygenation reactions and categorized the deoxygenation methods by different functionalities.

Mechanical Behaviour and Induced Microstructural Development upon Simultaneous and Balanced Biaxial Stretching of Poly(ethylene furandicarboxylate), PEF

The biaxial behavior of PEF has been analyzed for equilibrated and simultaneous biaxial stretching. The ability of PEF to develop an organized microstructure through strain induced crystallization (SIC) has been described. Upon biaxial stretching, SIC can be difficult to perform because the stretching is performed in two perpendicular directions. However, thanks to the time/temperature superposition principle and an accurate heating protocol, relevant stretching settings have been chosen to stretch the material in its rubbery-like state and to reach high levels of deformation. By the protocol applied, the mechanical behavior is easily transposable to the industry. This work has shown that PEF can, as in uniaxial stretching, develop well-organized crystals and a defined microstructure upon biaxial stretching. This microstructure allows the obtention of improved mechanical properties and thermal stability of the biaxially stretched samples. The crystals induced upon biaxial stretching are similar to the one that has been developed and observed after uniaxial stretching and upon static crystallization. Moreover, the furan cycles seem to appear in a state similar to the one of a sample crystallized upon quiescent condition. The rigidity is increased, and the α-relaxation temperature is increased by 15 °C.

Recent advances in the development of green furan ring-containing polymeric materials based on renewable plant biomass

Fossil resources are rapidly depleting, forcing researchers in various fields of chemistry and materials science to switch to the use of renewable sources and the development of corresponding technologies. In this regard, the field of sustainable materials science is experiencing an extraordinary surge of interest in recent times due to the significant advances made in the development of new polymers with desired and controllable properties. This review summarizes important scientific reports in recent times dedicated to the synthesis, construction and computational studies of novel sustainable polymeric materials containing unchanged (pseudo)aromatic furan cores in their structure. Linear polymers for thermoplastics, branched polymers for thermosets and other crosslinked materials are emerging materials to highlight. Various polymer blends and composites based on sustainable polyfurans are also considered as pathways to achieve high-value-added products.

Tailored Charge Transfer Kinetics in Precursors for Organic Radical Batteries: A Joint Synthetic-Theoretical Approach

The development of sustainable energy storage devices is crucial for the transformation of our energy management. In this scope, organic batteries attracted considerable attention. To overcome the shortcomings of typically applied materials from the classes of redox-active conjugated polymers (i. e., unstable cell voltages) and soft matter-embedded stable organic radicals (i. e., low conductivity), a novel design concept was introduced, integrating such stable radicals within a conductive polymer backbone. In the present theory-driven design approach, redox-active (2,2,6,6-tetramethylpiperidin-1-yl)oxyls (TEMPOs) were incorporated in thiophene-based polymer model systems, while structure-property relationships governing the thermodynamic properties as well as the charge transfer kinetics underlying the charging and discharging processes were investigated in a systematical approach. Thereby, the impact of the substitution pattern, the length as well as the nature of the chemical linker, and the ratio of TEMPO and thiophene units was studied using state-of-the-art quantum chemical and quantum dynamical simulations for a set of six molecular model systems. Finally, two promising candidates were synthesized and electrochemically characterized, paving the way to applications in the frame of novel organic radical batteries.

Biobased Transesterification Vitrimers

The rapid increase in the use of plastics and the related sustainability issues, including the depletion of global petroleum reserves, have rightly sparked interest in the use of biobased polymer feedstocks. Thermosets cannot be remolded, processed, or recycled, and hence cannot be reused because of their permanent molecular architecture. Vitrimers have emerged as a novel polymer family capable of bridging the difference between thermoplastic and thermosets. Vitrimers enable unique recycling strategies, however, it is still important to understand where the raw material feedstocks originate from. Transesterification vitrimers derived from renewable resources are a massive opportunity, however, limited research has been conducted in this specific family of vitrimers. This review article provides a comprehensive overview of transesterification vitrimers produced from biobased monomers. The focus is on the biomass structural suitability with dynamic covalent chemistry, as well as the viability of the synthetic methods.

Antibacterial Activity of Biodegradable Films Incorporated with Biologically-Synthesized Silver Nanoparticles and the Evaluation of Their Migration to Chicken Meat

The food industry has been exploring the association of polymers with nanoparticles in packaging production, and active products are essential to increase the shelf life of food and avoid contamination. Our study developed starch-poly (adipate co-terephthalate butyl) films with silver nanoparticles produced with Fusarium oxysporum components (bio-AgNPs), intending to control foodborne pathogens. The bio-AgNPs showed activity against different Salmonella serotypes, including multidrug-resistant Salmonella Saint Paul and Salmonella Enteritidis, with minimum bactericidal concentrations ranging from 4.24 to 16.98 µg/mL. Biodegradable films with bio-AgNPs inhibited the growth of up to 10⁶Salmonella isolates. Silver migration from the films to chicken was analyzed using electrothermal atomic absorption spectrophotometry, and the results showed migration values (12.94 mg/kg and 3.79 mg/kg) above the limits allowed by the European Food Safety Authority (EFSA) (0.05 mg/kg). Thus, it is necessary to improve the technique to avoid the migration of silver to chicken meat, since these concentrations can be harmful.

Enhancement of Cell Behavior by the Polysaccharide Extract of Arthrospira and Potential Biomedical Applications

Arthrospira is one of the most studied cyanobacteria and has been reported with practical applications. Among the substances derived from Arthrospira, polysaccharides have received relatively less attention than phycocyanins, though they have more abundant structural variations and specific properties. Herein, a new Arthrospira-derived sulfated polysaccharide was explored for its potential bioactive functions. The ability of this sulfated polysaccharide to promote the behavior of neural stem cells (NSCs) in three-dimensional hydrogel was examined for the first time. NSCs encapsulated in the sulfated polysaccharide-containing hydrogel showed better proliferation than the control hydrogel as well as a unique cell clustering behavior, i.e., formation of multicellular spherical clusters (40-60 μm). The sulfated polysaccharide, in an appropriate range of concentration (5 mg/mL), also maintained the stemness of NSCs in hydrogel and facilitated their differentiation. In addition, the potentials of the new sulfated polysaccharide as a coating material and as a component for drug carrier were verified. The sulfated polysaccharide-modified substrate exhibited superhydrophilicity (contact angle ~9°) and promoted cell adhesion to the substrate. Composite nanoparticles composed of the sulfated polysaccharide and other differently charged polysaccharides were produced with an average diameter of ~240 nm and estimated drug loading of ~18%. The new Arthrospira-derived sulfated polysaccharide is a promising candidate for cell culture, surface-modification, and drug-delivery applications in the biomedical field.

High Bio-Content Thermoplastic Polyurethanes from Azelaic Acid

To realize the commercialization of sustainable materials, new polymers must be generated and systematically evaluated for material characteristics and end-of-life treatment. Polyester polyols made from renewable monomers have found limited adoption in thermoplastic polyurethane (TPU) applications, and their broad adoption in manufacturing may be possible with a more detailed understanding of their structure and properties. To this end, we prepared a series of bio-based crystalline and amorphous polyester polyols utilizing azelaic acid and varying branched or non-branched diols. The prepared polyols showed viscosities in the range of 504–781 cP at 70 °C, with resulting TPUs that displayed excellent thermal and mechanical properties. TPUs prepared from crystalline azelate polyester polyol exhibited excellent mechanical properties compared to TPUs prepared from amorphous polyols. These were used to demonstrate prototype products, such as watch bands and cup-shaped forms. Importantly, the prepared TPUs had up to 85% bio-carbon content. Studies such as these will be important for the development of renewable materials that display mechanical properties suitable for commercially viable, sustainable products.

5-Hydroxymethylfurfural Oxidation to 2,5-Furandicarboxylic Acid on Noble Metal-Free Nanocrystalline Mixed Oxide Catalysts

Noble metal-free catalysts based on earth-abundant and inexpensive mixed oxides are active catalysts of all steps of the reaction cascade leading from 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) using tert-butyl hydroperoxide (TBHP) as oxidation agent. Catalysts covering the whole range of composition in the Cu-Mn and Co-Fe series have been prepared and characterised. The nature and composition of the catalyst strongly affect conversion and selectivity. The distribution of products indicates that radical-type oxygen species, deriving from the activation of TBHP, play a determining role in the reaction. The early steps of reaction mainly follow the pattern expected for heterogeneous Fenton catalysts. Mixed oxide catalysts are the most effective in further oxidation steps, leading to the formation of FDCA, both in the Cu-Mn and Co-Fe systems. This behaviour can be related to the distribution of charge in the mixed oxides, suggesting a possible implication of the lattice oxygen in the last reaction steps. The results provide indications on how to optimize the reaction and minimize the formation of byproducts (humins and oligomers).

Hydrophilic bio-based polymers by radical copolymerization of cyclic vinyl ethers derived from glycerol

In this study, novel functional polymers were obtained by using glycerol as a bio-based precursor, which is abundant and inexpensive renewable feedstock with a polyol skeleton. Cyclic vinyl ethers with acetal linkage were derived from glycerol to yield well-defined copolymers by reversible addition-fragmentation chain transfer (RAFT) radical copolymerization with common vinyl monomers. The resulting acetal-containing copolymers could be hydrolyzed under acidic conditions to afford water-soluble functional polymers with pendent diols.

Synthesis of 3-Aryl-3-(Furan-2-yl)Propanoic Acid Derivatives, and Study of Their Antimicrobial Activity

Reactions of 3-(furan-2-yl)propenoic acids and their esters with arenes in Brønsted superacid TfOH affords products of hydroarylation of the carbon–carbon double bond, 3-aryl-3-(furan-2-yl)propenoic acid derivatives. According to NMR and DFT studies, the corresponding O,C-diprotonated forms of the starting furan acids and esters should be reactive electrophilic species in these transformations. Starting compounds and their hydroarylation products, at a concentration of 64 µg/mL, demonstrate good antimicrobial activity against yeast-like fungi Candida albicans. Apart from that, these compounds suppress Escherichia coli and Staphylococcus aureus.

Recent Advances in Reductive Upgrading of 5-Hydroxymethylfurfural via Heterogeneous Thermocatalysis

The catalytic conversion of 5-hydroxymethylfufural (HMF), one of the vital platform chemicals in biomass upgrading, holds great promise for producing highly valuable chemicals through sustainable routes, thereby alleviating the dependence on fossil feedstocks and reducing CO₂ emissions. The reductive upgrading (hydrogenation, hydrogenolysis, ring-opening, ring-rearrangement, amination, etc.) of HMF has exhibited great potential to produce monomers, liquid fuel additives, and other valuable chemicals. Thermocatalytic conversion has a significant advantage over photocatalysis and electrocatalysis in productivity. In this Review, the recent achievements of thermo-reductive transformation of HMF to various chemicals using heterogeneous catalytic systems are presented, including the catalytic systems (catalyst and solvent), reaction conditions, (reaction temperature, pressure, etc.), and reaction mechanisms. The current challenges and future opportunities are discussed as well, aiming at guiding the catalyst design and practical scalable productions.

Toward Green Atom Transfer Radical Polymerization: Current Status and Future Challenges

Reversible-deactivation radical polymerizations (RDRPs) have revolutionized synthetic polymer chemistry. Nowadays, RDRPs facilitate design and preparation of materials with controlled architecture, composition, and functionality. Atom transfer radical polymerization (ATRP) has evolved beyond traditional polymer field, enabling synthesis of organic-inorganic hybrids, bioconjugates, advanced polymers for electronics, energy, and environmentally relevant polymeric materials for broad applications in various fields. This review focuses on the relation between ATRP technology and the 12 principles of green chemistry, which are paramount guidelines in sustainable research and implementation. The green features of ATRP are presented, discussing the environmental and/or health issues and the challenges that remain to be overcome. Key discoveries and recent developments in green ATRP are highlighted, while providing a perspective for future opportunities in this area.

Catalyst Engineering Empowers the Creation of Biomass-Derived Polyesters and Polycarbonates

ConspectusThe introduction of circular principles in chemical manufacturing will drastically change the way everyday plastics are produced, thereby affecting several aspects of the respective value chains in terms of raw feedstock, recyclability, and cost. The ultimate aim is to ensure a paradigm shift toward plastic-based (consumer) materials that overall can offer a more attractive and sustainable carbon footprint, which is an important requisite from a societal, political, and eventually economical point of view. To realize this important milestone, it is vitally important to control the polymerization processes associated with the creation of novel sustainable materials. In this respect, we realized that expanding the portfolio of biomass-derived monomers may indeed create an impetus for atom circularity; however, the often sterically congested nature of biomass-derived monomers minimizes the ability of previously developed catalysts to activate and transform these precursors. Our motivation was thus spurred by an apparent lack of catalysts suitable for addressing the conversion of such biomonomers, as we realized the potential that new catalytic processes could have to advance and contribute to the development of sustainable materials produced from polycarbonates and polyesters. These two classes of polymers represent crucial ingredients of important and large-scale consumer products and are therefore ideal fits for implementing new catalytic protocols that enable a gradual transition to plastic materials with an improved carbon footprint.When we started our research expedition, the field was dominated by metal catalysts that incorporated preferred, and in some cases even privileged, ligand backbones (such as salens) able to mediate both ring-opening and ring-opening copolymerization manifolds. One major drawback of these aforementioned catalysts is their rather rigid nature, a feature that reduces their ability to act as adaptive systems, especially in cases where bulky monomers are involved. While our initial focus was on the utilization of sustainable metal salen complexes (M = Zn, Fe) for the activation of small cyclic ethers, which are privileged monomers for polyester and polycarbonate production, we were rapidly confronted with severe limitations related to their inability to activate a wider range of complex epoxides and oxetanes, which was imparted by the planar coordination geometry of the salen ligand in most of its applied metal complexes. In our quest to find a catalytically more effective metal complex with the ability to electronically and sterically tune its substrate-binding and substrate-activation potential, we identified aminotriphenolates as structurally versatile, easily accessible, and scalable ligands for various earth-abundant metal cations. Moreover, the ligand backbone allows for switchable coordination environments around the metal centers, thus offering the necessary adaptation in substrate activation events.This Account describes how Al(III)- and Fe(III)-centered aminotriphenolates have conquered a prominent position as catalyst components in the synthesis of new biobased polyester and polycarbonate architectures, thereby changing the landscape of previously difficult to convert biomonomers, and expanding the chemical space of biobased functional polymers. With the ever-increasing influence of legislation and the restrictions placed on the use of fossil-fuel-based feedstock, the polymer industry needs viable alternatives to design materials that are greener, cost-effective, and allow for the exploration and optimization of their recycling and properties.

Closing the Carbon Loop in the Circular Plastics Economy

Today, plastics are ubiquitous in everyday life, problem solvers of modern technologies, and crucial for sustainable development. Yet the surge in global demand for plastics of the growing world population has triggered a tidal wave of plastic debris in the environment. Moving from a linear to a zero-waste and carbon-neutral circular plastic economy is vital for the future of the planet. Taming the plastic waste flood requires closing the carbon loop through plastic reuse, mechanical and molecular recycling, carbon capture, and use of the greenhouse gas carbon dioxide. In the quest for eco-friendly products, plastics do not need to be reinvented but tuned for reuse and recycling. Their full potential must be exploited regarding energy, resource, and eco efficiency, waste prevention, circular economy, climate change mitigation, and lowering environmental pollution. Biodegradation holds promise for composting and bio-feedstock recovery, but it is neither the Holy Grail of circular plastics economy nor a panacea for plastic littering. As an alternative to mechanical downcycling, molecular recycling enables both closed-loop recovery of virgin plastics and open-loop valorization, producing hydrogen, fuels, refinery feeds, lubricants, chemicals, and carbonaceous materials. Closing the carbon loop does not create a Perpetuum Mobile and requires renewable energy to achieve sustainability. This article is protected by copyright. All rights reserved.

Conditions to Control Furan Ring Opening during Furfuryl Alcohol Polymerization

The chemistry of biomass-derived furans is particularly sensitive to ring openings. These side reactions occur during furfuryl alcohol polymerization. In this work, the furan ring-opening was controlled by changing polymerization conditions, such as varying the type of acidic initiator or the water content. The degree of open structures (DOS) was determined by quantifying the formed carbonyl species by means of quantitative 19F NMR and potentiometric titration. The progress of polymerization and ring opening were monitored by DSC and FT-IR spectroscopy. The presence of additional water is more determining on ring opening than the nature of the acidic initiator. Qualitative structural assessment by means of 13C NMR and FT-IR shows that, depending on the employed conditions, poly(furfuryl alcohol) samples can be classified in two groups. Indeed, either more ester or more ketone side groups are formed as a result of side ring opening reactions. The absence of additional water during FA polymerization preferentially leads to opened structures in the PFA bearing more ester moieties.

Glassy-like Metal Oxide Particles Embedded on Micrometer Thicker Alginate Films as Promising Wound Healing Nanomaterials

Micrometer-thicker, biologically responsive nanocomposite films were prepared starting from alginate-metal alkoxide colloidal solution followed by sol-gel chemistry and solvent removal through evaporation-induced assembly. The disclosed approach is straightforward and highly versatile, allowing the entrapment and growth of a set of glassy-like metal oxide within the network of alginate and their shaping as crake-free transparent and flexible films. Immersing these films in aqueous medium triggers alginate solubilization, and affords water-soluble metal oxides wrapped in a biocompatible carbohydrate framework. Biological activity of the nano-composites films was also studied including their hemolytic activity, methemoglobin, prothrombin, and thrombine time. The effect of the films on fibroblasts and keratinocytes of human skin was also investigated with a special emphasis on the role played by the incorporated metal oxide. This comparative study sheds light on the crucial biological response of the ceramic phase embedded inside of the films, with titanium dioxide being the most promising for wound healing purposes.