Synthesis Of Polyesters Research Articles

Recent progress in primitive polyester synthesis and membraneless microdroplet assembly.

While it is often believed that the origins of life required participation of early biomolecules, it has been recently proposed that "non-biomolecules", which would have been just as, if not more, abundant on early Earth, could have played a part. In particular, recent research has highlighted the various ways by which polyesters, which do not participate in modern biology, could have played a major role during the origins of life. Polyesters could have been synthesized readily on early Earth through simple dehydration reactions at mild temperatures involving abundant "non-biological" alpha hydroxy acid (AHA) monomers. This dehydration synthesis process results in a polyester gel, which upon further rehydration, can assemble into membraneless droplets proposed to be protocell models. These proposed protocells can provide functions to a primitive chemical system, such as analyte segregation or protection, which could have further led to chemical evolution from prebiotic chemistry to nascent biochemistry. Here, to further shed light into the importance of "non-biomolecular" polyesters at the origins of life and to highlight future directions of study, we review recent studies which focus on primitive synthesis of polyesters from AHAs and assembly of these polyesters into membraneless droplets. Specifically, most of the recent progress in this field in the last five years has been led by laboratories in Japan, and these will be especially highlighted. This article is based on an invited presentation at the 60th Annual Meeting of the Biophysical Society of Japan held in September, 2022 as an 18th Early Career Awardee.

Levoglucosenone-derived synthesis of bio-based solvents and polyesters

ABSTRACT Polyesters are important materials with a wide range of applications, but there has been increasing concern over their sustainability. One example is the need for safer, bio-derived solvents to replace those currently in use for the polymer’s synthesis and processing. In this work, several variants of the bio-based cellulose/levoglucosenone derived solvent Cyrene, namely the ketal derivatives dioxolane Cygnet, dioxane Cygnet and dioxepane Cygnet were synthesized and tested as media for enzymatic polycondensation reactions using bio-based building blocks. Dioxolane Cygnet and dioxepane Cygnet were found to be suitable solvents for enzymatic polycondensation reactions, with dioxolane Cygnet being the preferred solvent, yielding polymers with a Mn >22 kDa. In addition, these solvents were tested in the biocatalyzed synthesis of levoglucosenone-based polyesters. The alternative solvents gave superior yields to those previously observed, demonstrating the versatility of these solvents in enzymatic polycondensation reactions, representing the first synthetic polymer-solvent system fully derived from cellulose.

Citronella-based polyesters by organocatalyzed ring-opening polymerization and their recyclable crosslinked films

Independence of food supply chain is a grand challenge encountered by the development of bio-based polymers. Here, we demonstrate the synthesis of amorphous aliphatic polyesters via organocatalyzed ring-opening polymerization of 9-membered lactone monomer, a novel downstream product of non-edible citronella oil. In particular, chemical transformation of trisubstituted alkene moiety owned by this renewable biomass was achieved by cross-metathesis of this bulky group with methyl acrylate. Three-armed star polymers were converted to free-standing films by UV-induced crosslinking. In particular, these crosslinked thin films could be efficiently recycled as ω-hydroxy ester upon methanolysis. This work opens a new avenue for the synthesis and application of terpene- and terpenoid-based polymers.

Poly(pro-curcumin) Materials Exhibit Dual Release Rates and Prolonged Antioxidant Activity as Thin Films and Self-Assembled Particles.

Curcumin is a natural polyphenol that exhibits remarkable antioxidant and anti-inflammatory activities; however, its clinical application is limited in part by its physiological instability. Here, we report the synthesis of curcumin-derived polyesters that release curcumin upon hydrolytic degradation to improve curcumin stability and solubility in physiological conditions. Curcumin was incorporated in the polymer backbone by a one-pot condensation polymerization in the presence of sebacoyl chloride and polyethylene glycol (PEG, Mn = 1 kDa). The thermal and mechanical properties, surface wettability, self-assembly behavior, and drug-release kinetics all depend sensitively on the mole percentage of curcumin incorporated in these statistical copolymers. Curcumin release was triggered by the hydrolysis of phenolic esters on the polymer backbone, which was confirmed using a PEGylated curcumin model compound, which represented a putative repeating unit within the polymer. The release rate of curcumin was controlled by the hydrophilicity of the polymers. Burst release (2 days) and extended release (>8 weeks) can be achieved from the same polymer depending on curcumin content in the copolymer. The materials can quench free radicals for at least 8 weeks and protect primary neurons from oxidative stress in vitro. Further, these copolymer materials could be processed into both thin films and self-assembled particles, depending on the solvent-based casting conditions. Finally, we envision that these materials may have potential for neural tissue engineering application, where antioxidant release can mitigate oxidative stress and the inflammatory response following neural injury.

Synthesis and characterization of novel bio-based polyesters and poly(ester amide)s based on isosorbide and symmetrical cyclic anhydrides

Synthesis and characterization of novel bio-based polyesters and poly(ester amide)s based on isosorbide and symmetrical cyclic anhydrides

Synthesis and hydrolytic degradation of poly (glycerol succinate) based polyesters

The limited availability of petroleum resources motivates the research towards value-added products production from bio-resources. This study reports the synthesis of glycerol and succinic acid-based polyesters and their detailed characterization. The modification of poly (glycerol succinate) was done by using other diacids like glutaric acid, adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. The sysnthesized polyesters were characterized using various techniques such as thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), Nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The addition of different dicarboxylic acids to poly (glycerol succinate) based co-polyesters increased the thermal stability of poly (Glycerol succinate). Glass transition temperatures were obtained in the range of −17.2 to −22.5 °C and it increased with chain length. The progress of reaction was monitored by determining acid number, ester number, and degree of esterification. The hydrolytic degradation of polyesters was carried out in acidic and basic medium. The polyesters was found to degrade under basic conditions whereas no weight loss of poly (glycerol succinate) was found under acidic conditions. Particularly, about 40% of poly (glycerol succinate) was degraded within 24 h under basic conditions (pH = 12). The analysis of morphology of polyesters during degradation showed that the increase in hydrolysis time increased the heterogeneity in polyester matrix.

Overcoming the low reactivity of biobased, secondary diols in polyester synthesis

Shifting away from fossil- to biobased feedstocks is an important step towards a more sustainable materials sector. Isosorbide is a rigid, glucose-derived secondary diol, which has been shown to impart favourable material properties, but its low reactivity has hampered its use in polyester synthesis. Here we report a simple, yet innovative, synthesis strategy to overcome the inherently low reactivity of secondary diols in polyester synthesis. It enables the synthesis of fully biobased polyesters from secondary diols, such as poly(isosorbide succinate), with very high molecular weights (Mn up to 42.8 kg/mol). The addition of an aryl alcohol to diol and diacid monomers was found to lead to the in-situ formation of reactive aryl esters during esterification, which facilitated chain growth during polycondensation to obtain high molecular weight polyesters. This synthesis method is broadly applicable for aliphatic polyesters based on isosorbide and isomannide and could be an important step towards the more general commercial adaption of fully biobased, rigid polyesters.

Synthesis and properties of high performance biobased liquid crystal polyester based on furandicarboxylic acid and sebacic acid

In this study, a series of high-performance biobased liquid crystal copolyesters derived from 6-hydroxy-2-naphthoic acid (HNA), 4, 4ʹ-Dihydroxybiphenyl (BP), biobased 2,5-furandicarboxylic acid (FDCA) and sebacic acid (SeA) were successfully designed and prepared via “one-pot” melt polycondensation method. The addition of nonlinear and rigid FDCA units broke the regularity of the molecular chain but increased the chain rigidity, thus, endowing the unique thermal behavior, which the melting temperature decreased from 163.0 to 125.3 ℃, while the glass transition temperature decreased first and then increased slightly to 75.7 ℃ as increased the FDCA units to 7.5 mol%. Furthermore, DSC and XRD results showed that a small amount (1 mol%) of FDCA units did not impair crystallization ability of the copolyesters, whereas excess of FDCA hindered the molecular chain packing. The DMA results also demonstrated that the addition of FDCA restricts the chain motion and improves the rigidity of the copolyester as reflected by the higher storage modulus. The incorporation of nonlinear FDCA units lowered the initial degradation temperature slightly, but still exhibited enough thermal stability to be melt processed as compared with its relative low melting temperatures. The copolyesters exhibited a broad temperature range of nematic liquid crystal phase as well as shear thinning and viscous melt flow behavior, which were beneficial for its melt processing. The tensile strength and modulus of the injection molded splines were in range of 82.51–103.27 MPa and 2.05–2.72 GPa, respectively, which were much higher than the common biobased copolyesters such as PLA, PCL and other FDCA-containing polyesters. The increased modulus and decreased fracture strain of the copolyesters containing FDCA units further verified the high rigidity of the molecular chain. Moreover, the in-vitro cytotoxicity and water contact angle results proved that the copolyesters have good biocompatibility. The resulted copolyesters combined with excellent melt processing ability, mechanical property and good biocompatibility have great promising applications as biomedical and biodegradable materials.

Recent Advances in the Enzymatic Synthesis of Polyester.

Polyester is a kind of polymer composed of ester bond-linked polybasic acids and polyol. This type of polymer has a wide range of applications in various industries, such as automotive, furniture, coatings, packaging, and biomedical. The traditional process of synthesizing polyester mainly uses metal catalyst polymerization under high-temperature. This condition may have problems with metal residue and undesired side reactions. As an alternative, enzyme-catalyzed polymerization is evolving rapidly due to the metal-free residue, satisfactory biocompatibility, and mild reaction conditions. This article presented the reaction modes of enzyme-catalyzed ring-opening polymerization and enzyme-catalyzed polycondensation and their combinations, respectively. In addition, the article also summarized how lipase-catalyzed the polymerization of polyester, which includes (i) the distinctive features of lipase, (ii) the lipase-catalyzed polymerization and its mechanism, and (iii) the lipase stability under organic solvent and high-temperature conditions. In addition, this article also focused on the advantages and disadvantages of enzyme-catalyzed polyester synthesis under different solvent systems, including organic solvent systems, solvent-free systems, and green solvent systems. The challenges of enzyme optimization and process equipment innovation for further industrialization of enzyme-catalyzed polyester synthesis were also discussed in this article.

Synthesis, physical properties, and functionalization of biobased unsaturated polyesters derived from Cis-2-butene-1,4-diol

This work describes the synthesis, thermomechanical properties, and functionalization of unsaturated polyesters based on biobased cis-2-butene-1, 4-diol (cB). Under an optimized experimental process, polyesters were synthesized by melt polycondensation employing cB and α, ω-diacids with even chain length. The high molecular weight of Mw up to79.5 kDa was achieved for the poly(cis-butene dicarboxylate)s (PcBX), and meanwhile without isomerization or branching side reactions occurring in the polycondensation. Hence, cB was a suitable unsaturated diol for direct usage in the preparation of linear unsaturated polyester with high molecular mass. The result of mechanical properties indicated that cB outperforms 1, 4-butanediol in regard to enhancing the mechanical property of polyesters. Satisfactory thermal and crystal performances, broad processing window, as well as excellent mechanical properties were presented for PcBX, indicating that these synthetic biobased polyesters were promising candidates for replacing petroleum-based polyesters in practical application. Furthermore, an attempt was made to incorporate the functional group of hydroxyls in the backbones through “click reaction”, and the existence of free hydroxyls on the surface of PcBX results in their greatly improved hydrophilicity. The inserted hydroxyls greatly accelerated the degradation rate of polyesters. Overall, this paper not only offers a straightforward method for the preparation of high molecular mass unsaturated polyesters with adjustable performances, but also presents the potential of functionalization for a broad range of applications.

One-Pot Terpolymerization of Macrolactones with Limonene Oxide and Phtalic Anhydride to Produce di-Block Semi-Aromatic Polyesters.

The synthesis of novel block copolymers, namely poly(limonene-phthalate)-block-poly(pentadecalactone) and poly(limonene-phthalate)-block-poly(pentadecalactone) is here described. To achieve this synthesis, a bimetallic aluminum based complex (1) was used as catalyst in the combination of two distinct processes: the ring-opening polymerization (ROP) of macrolactones such as ω-pentadecalactone (PDL) and ω-6-hexadecenlactone (HDL) and the ring-opening copolymerization (ROCOP) of limonene oxide (LO) and phthalic anhydride (PA). The synthesis of di-block polyesters was performed in a one-pot procedure, where the semi-aromatic polyester block was firstly formed by ROCOP of LO and PA, followed by the polyethylene like portion produced by ROP of macrolactones (PDL or HDL). The obtained di-block semiaromatic polyesters were characterized by NMR and GPC. The structural organization was analyzed through XRD. Thermal properties were evaluated using differential thermal analysis (DSC) and thermogravimetric measurements (TGA) either in air or in nitrogen atmosphere.

Tissue-specific regulation of lipid polyester synthesis genes controlling oxygen permeation into Lotus japonicus nodules

Legumes establish endosymbiotic associations with nitrogen-fixing rhizobia, which they host inside root nodules. Here, specific physiological and morphological adaptations, such as the production of oxygen-binding leghemoglobin proteins and the formation of an oxygen diffusion barrier in the nodule periphery, are essential to protect the oxygen-labile bacterial nitrogenase enzyme. The molecular basis of the latter process remains elusive as the identification of required genes is limited by the epistatic effect of nodule organogenesis over nodule infection and rhizobia accommodation. We overcame this by exploring the phenotypic diversity of Lotus japonicus accessions that uncouple nodule organogenesis from nodule infection when inoculated with a subcompatible Rhizobium strain. Using comparative transcriptomics, we identified genes with functions associated with oxygen homeostasis and deposition of lipid polyesters on cell walls to be specifically up-regulated in infected compared to noninfected nodules. As hydrophobic modification of cell walls is pivotal for creating diffusion barriers like the root endodermis, we focused on two Fatty acyl-CoA Reductase genes that were specifically activated in the root and/or in the nodule endodermis. Mutant lines in a Fatty acyl-CoA Reductase gene expressed exclusively in the nodule endodermis had decreased deposition of polyesters on this cell layer and increased nodule permeability compared to wild-type plants. Oxygen concentrations were significantly increased in the inner cortex of mutant nodules, which correlated with reduced nitrogenase activity, and impaired shoot growth. These results provide the first genetic evidence for the formation of the nodule oxygen diffusion barrier, a key adaptation enabling nitrogen fixation in legume nodules.

Stereocontrolled acyclic diene metathesis polymerization.

The cis/trans geometry of olefins is known to dramatically influence the thermal and mechanical properties of polyalkenamers. Yet, polymerization methods that efficiently control this parameter are scarce. Here we report the development of a stereoretentive acyclic diene metathesis polymerization that uses the reactivity of dithiolate Ru carbenes combined with cis monomers. These Ru catalysts exhibit exquisite retention of the cis geometry and tolerate many polar functional groups, enabling the synthesis of all-cis polyesters, polycarbonates, polyethers and polysulfites. The stereoretentive acyclic diene metathesis polymerization is also characterized by low catalyst loadings and tolerance towards trans impurities in the monomer batch, which should facilitate large-scale implementation. Modulation of the reaction temperature and time leads to an erosion of stereoretention, permitting a stereocontrolled synthesis of polyalkenamers with predictable cis:trans ratios. The impact of the stereochemistry of the repeating alkenes on the thermal properties is clearly demonstrated through differential scanning calorimetry and thermogravimetric analysis.

Synthesis and chemoselective crosslinking of functionalized polyesters from bio‐based epoxides and cyclic anhydrides

AbstractBiomass derivable epichlorohydrin undergoes ring‐opening copolymerization with either succinic or itaconic anhydride (both biosourcable) under standard laboratory conditions using metal‐based or an entirely organic initiator to form highly functionalized, low molecular weight polyesters. The linear polyesters obtained from epichlorohydrin and itaconic anhydride contain both alkyl chlorides and α,β‐unsaturated esters and can be crosslinked to form insoluble resins by treatment with di‐ to tetra‐functional amines and thiols. Crosslinking with amines predominately occurs through the alkyl chlorides whilst crosslinking with thiols occurs through the α,β‐unsaturated esters allowing the synthesis of insoluble polyester derived resins with complementary and controllable functionalities.

Synthesis of Functional Polyesters N-(2,3-epoxypropyl)-4,5,6,7-tetrahydroindole by Anionic Ring-Opening Polymerization.

The functional polyethers of N-(2,3-epoxypropyl)-4,5,6,7-tetrahydroindole (in up to 61% yield, Mw = 8.7–11.7 kDa) and copolymers with ethylene glycol methylglycidyl ether (Mw = 5.6–14.2 kDa) and ethylene glycol vinylglycidyl ether (Mw = 6.4–12.3 kDa) have been synthesized via anionic ring-opening polymerization in the presence of KOH without solvent. The polymerization involves the opening of the epoxy ring to deliver the linear polyethers bearing free tetrahydroindole rings and oxyethylene or vinyloxy groups in the side chain. The polyethers are soluble in ethanol, benzene, chloroform, dioxane, DMF, and DMSO. The polyethers obtained exhibit the properties of high-resistance organic semiconductors: their electrical conductivity reaches 10−14 S/cm.

Efficient oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid by a two-enzyme system: Combination of a bacterial laccase with catalase

2,5-Furandicarboxylic acid (FDCA) can be used for synthesis of various polyesters and polyamides. It can be produced from oxidation of 5-hydroxymethylfurfural (HMF), a biomass-based platform chemical. In this work, a new catalyst CotA laccase/TEMPO/catalase has been presented and used for efficient and selective oxidation of HMF to FDCA. Dioxygen O2, which is in-situ generated from the decomposition of H2O2 by catalase, is used as the oxidant. In comparison to using ambient air as the oxidant, using the in-situ generated O2 as the oxidant has significantly increased the catalytic efficiency. Dioxygen O2 can be generated in a convenient and easy way using clean H2O2 as the source. It has been found that continuous generation of O2 is essential, and over generation of O2 is not necessary because of the limitation of the O2 diffusion into the inner space of CotA laccase. It has been demonstrated that, by coupling with the electron transfer mediator TEMPO and catalase, the bacterial laccase can efficiently oxidize HMF to produce FDCA.

Evaluation of biocatalytic pathways in the synthesis of polyesters: Towards a greener production of surgical sutures

AbstractThis review presents an updated and alternative perspective on enzymatic synthesis to obtain polyesters, with a focus on the precursor materials for absorbable sutures: poly‐lactic, poly‐glycolic, and poly‐lactic‐co‐glycolic acids. Currently, the profitable path towards the industrial synthesis of polyesters is ring‐opening polymerization (ROP) of lactones, which is an experimentally complex process and implies a hazardous environmental impact due to the need for energy consumption, use of large volumes of toxic organic solvents and of non‐biocompatible metal‐based catalysts. On the contrary, enzymatically driven reactions may be performed under mild conditions in simple reactors. Mechanistic and experimental issues of the two major biocatalyzed strategies ‐direct condensation and ROP‐ were analyzed from a green chemistry perspective. These enzyme‐catalyzed poly‐esterifications often return low yield and/or low final molecular weight (Mw). Considering all the analyzed published data available, possible strategies to overcome these limitations were postulated: implementation of aqueous biphasic reaction systems, use of ultrasound agitation and sequential addition of reactants or co‐solvents. To promote Mw increment, post‐reaction treatments can be carried out such as thermally induced short‐chain polymerization under vacuum and incorporation of glycols as chain extenders.

Greener Synthesis Route for Furanic-Aliphatic Polyester: Enzymatic Polymerization in Ionic Liquids and Deep Eutectic Solvents

The development of bio-based polymers is growing not only due to their abundance in nature but also mainly because of the current issues with fossil-based plastics. Enzymatic polymerizations are a promising way to produce such polymers since they are known to be environmentally friendly. Sustainable polymers that require a greener production process can be realized easily via this polymerization route. However, the use of organic solvents is often one of the drawbacks in developing pathways toward fully green enzymatic polymerization methods. Therefore, in the present work, a series of fully bio-based polyesters based on 2,5-furandicarboxylic acid (FDCA), namely, furanic-aliphatic polyesters (FPEs), were enzymatically synthesized using greener solvents, such as ionic liquids (ILs) and deep eutectic solvents (DESs). The enzymatic polymerization in ILs and DESs effectively leads to the FDCA-based polyesters without any byproduct, which frequently causes coloration using traditional polymerization methods. FPEs with Mw up to 5.4 kg mol–1 were successfully achieved by Novozyme 435-catalyzed polycondensation of dimethyl 2,5-furandicarboxylate (DMFDCA) with aliphatic diols in BMIMPF6. Polymerization in DESs was also successfully conducted, resulting in the synthesis of bio-based polyesters, which can be further functionalized. Characterization using TGA, DSC, and WAXD showed that all obtained FPEs are semi-crystalline materials, which decomposed around 390 °C with a Tm of 68–123 °C and Tg of 3–12 °C. With this, we successfully developed more eco-friendly enzymatic synthesis routes for the production of sustainable polyesters

Synthesis and structure-property relationship of thermotropic liquid crystalline polyesters containing thiophene-aromatic and cycloaliphatic moieties

ABSTRACT We report the structure and property characterization of a series of thermotropic liquid crystalline polyesters (TLCPs) composed of three different repeating units based on 1,4-hydroxybenzoic acid (HBA), 6-hydroxy-2-naphthoic acid (HNA), and 2,5-thiophenedicarboxylic acid/1,4-cyclohexanedimethanol (TDCA/CHDM), which are synthesized through two-step melt polymerization. The effect of the TDCA/CHDM-based repeating unit (0.0–10.0 mol%) on the structure, thermal and mechanical properties of the TLCPs with 75.0 mol% HBA and 25.0–15.0 mol% HNA were investigated. The polarized optical and electron microscopic images confirmed the presence of thermotropic liquid crystalline and fibrillar structures for all synthesized TLCPs. The glass transition and melting temperatures as well as the crystallinity index of the TLCPs were found to increase with increment of the TDCA/CHDM unit up to 5.0 mol% due to the improved interchain packing, but they decreased at higher amounts of 7.5–10.0 mol% TDCA/CHDM units owing to the enhanced flexibility by the cyclohexylene ring and the mismatching in the length between HNA and TCDA/CHDM units. In addition, there was a crystal lattice transition of TLCPs from pseudo-hexagonal to orthorhombic phases. Although the thermal decomposition temperature and elastic storage moduli of the TLCPs decreased with the amount of the TDCA/CHDM unit, all TLCPs remained stable up to 300°C and had excellent elastic moduli above 4.1 GPa at 50°C.

Efficient Synthesis of Itaconate Polyesters with Amine-Triggered Rapid Degradation and Outstanding Mechanical Properties: An Experimental and Theoretical Study on Degradation Mechanisms

A range of degradable polyesters have been developed as sustainable alternatives for commercial plastics; however, limitations of composting facilities and uncontrolled degradation in the environment hindered their viability. In this study, biobased itaconic acid was selected as an active site to control the degradation of polyesters. A series of PBXI copolyesters with Mw’s ranging from 4.86 to 8.31 × 104 g/mol and high intrinsic viscosities of more than 1.15 dL/g were successfully synthesized without any cross-linking by selecting appropriate reaction conditions, including condensation temperature and vacuum, effective inhibitor, and catalyst. The obtained copolyesters were semicrystalline, and their Tm’s could be regulated from 42.5 to 179.5 °C. They exhibited outstanding elastic modulus (120–598 MPa) and tensile strength (17.9–51.4 MPa) among degradable polymers. Degradation experiments demonstrated that the incorporation of itaconate segments could facilitate both the hydrolysis and enzymatic degradation of polyesters. The state-of-the-art computation and analysis via molecular dynamics (MD) simulations of PBXI–CALB complexes elucidated the enzymatic degradation mechanism. Experimental results proved that, at room temperature, the degradation could be stimulated and regulated by amines without a catalyst and the Mn’s of lactamization products rapidly decreased to less than 5000 g/mol within 24 h. Moreover, the copolymerized structure of copolyesters and solvent factors could influence the aza-Michael addition between amines and itaconate units. This work provides a strategy to synthesize biodegradable copolymers with the potential to undergo controlled and rapid in vivo degradation with outstanding mechanical properties.