Series Of Polyesters Research Articles

A Facile Approach to Construct Novel Polyesters as Soft Midblock for Thermoplastic Elastomers.

The development of innovative synthetic strategies to create functional polycaprolactones is highly demanded for advanced material applications. In this contribution, we reported a facile synthetic strategy to prepare a class of CL-based monomers (R-TO) derived from epoxides. They readily polymerize via well-controlled ring-opening polymerization (ROP) to afford a series of polyesters P(R-TO) with high molecular weight (Mn up to 350 kDa). Sequential addition copolymerization of MTO and L-lactide (L-LA) allowed to access of a series of ABA triblock copolymers with composition-dependent mechanical properties. Notably, P(L-LA)100-b-P(MTO)500-b-P(L-LA)100 containing the amorphous P(MTO) segment as a soft midblock and crystalline P(L-LA) domain as hard end block behaved as an excellent thermoplastic elastomer (TPE) with high elongation at break (1438±204 %), tensile strength (23.5±1.7 MPa), and outstanding elastic recovery (>88 %).

Facile Green Synthesis of Zingerone Based Tissue‐Like Biodegradable Polyester with Shape‐Memory Features for Regenerative Medicine

AbstractThe abundance of plants as a renewable bioresource has captured the significant attention of researchers, driving them to explore new biodegradable polymeric materials. However, there are still many biobased materials with untapped potential, offering opportunities to synthesize novel biodegradable polymers with multifunctional properties. This work provides a unique solvent and catalyst‐free melt polycondensation process to prepare a series of polyesters using zingerol (Zing‐OH), a reduced form of zingerone, as a primary component for the first time. Briefly, Zing‐OH (a ginger‐based component) is employed in conjunction with a variety of renewable resources, such as citric acid (CA), sebacic acid (SA), and xylitol (Xy), to synthesize multifunctional soft tissue‐like ZCSX polyesters. Fourier‐transform infrared (FTIR) and 1H‐nuclear magnetic resonance (NMR) spectroscopy are used to validate the synthesis of the polyesters, while thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and universal testing machine (UTM) are employed to investigate their physicochemical properties. Moreover, the synthesized polyester's thermal, mechanical, and biodegradation properties can be fine‐tuned by simply varying the Zing‐OH feed ratio. The mechanical properties of the synthesized polymer resemble various human tissues, including the liver, uterus, bladder, breast, and temporal and nasal cartilage. This suggests that the synthesized polyesters can potentially be useful in tissue engineering applications. Furthermore, the polyester demonstrated exceptional recovery responses and good shape memory behavior at ambient body temperature. Additionally, as observed from Alamar blue, live/dead assays, and time‐dependent in vitro wound images, the synthesized polyester demonstrated antibacterial activity, good in vitro cytocompatibility, cell proliferation, and wound healing capabilities against mouse fibroblast cells (NIH/3T3). The developed biocompatible polyester also exhibits excellent hemocompatibility for human blood, indicating its potential use in the field of regenerative medicine.

Synthesis, Characterization, and Fluorescence Study of New Polyesters Derived from Curcumin Analogs

This work describes the synthesis, characterization, and evaluation of a new series of polyesters. The polyesters were synthesized by condensation polymerization using curcumin analogs as one monomer while the other monomer was of sebacoyl chloride and adipoyl chloride. The chalcones monomers were prepared by aldol condensation reactions. The structure of the prepared polyesters was characterized by FTIR spectra. The thermal stability of the new polymers was measured by thermogravimetric method. The solubility of the polymers in organic solvents was also studied. The prepared polyesters were found to possess fluorescent properties, and some of them were found to have good emissive properties.

Thermal homeotropic self-alignment on a single substrate of new series of discotic nematic triphenylene-based main-chain polyesters

We present the synthesis, characterization, and study of Liquid Crystal properties of a new series of polyesters containing 2,7-di-functionalized triphenylene units in the main chain, whose distinctive feature is that the carboxyl moiety is distant from the aromatic core. Several molecular aspects, such as the distance between the carboxylic group to the core, the length of the connector, and the orientation of the carboxyls were analyzed. In addition, we have investigated the influence of these molecular parameters on the thermal self-alignment of the polymers on different substrates. We have found a simple method to obtain a monodomain homeotropic orientation of these polyesters on a single substrate.

Synthesis and properties of biodegradable aliphatic–aromatic polyesters derived from 4‐hydroxybenzaldehyde

AbstractA novel biphenyl monomer, diethyl 6,6′‐dimethoxy‐[1,1′‐bipheny]‐3,3′‐dicarboxylate (DDBD), was synthesized from 4‐hydroxybenzaldehyde, a phenolic compound derived from lignin. A series of polyesters were prepared by polycondensation of the biphenyl monomer with hydroquinone bis(2‐hydroxyethyl) ether and aliphatic diacids via a two‐step melt polycondensation method. It was shown that the properties of the polyesters can be tuned by varying the length and the structure of the spacer in the aliphatic diacid monomers. Structure–property relations for these materials were investigated by Fourier‐transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. GPC analysis showed that the weight‐average molecular weight (Mw) of the samples varied from 4.2–5.0 × 104 g/mol, while thermal analysis yielded Tg values of 51–120°C, and 5% decomposition temperatures (Td,5%) of 327–389°C. All the samples exhibited a high yield strength (56–87 MPa). After 30 weeks of degradation in soil, the copolyesters had mass losses of up to 4.4%, and an investigation of the ecotoxicity of the copolyesters with Eisenia fetida yielded a survival rate of over 80% after 14 days for the different copolyesters, suggesting low toxicity in the environment. Overall, these copolyesters have good properties and would be suitable to replace petroleum‐based commercial poly(ethylene terephthalate) packaging materials.

Development of Biodegradable Polyesters: Study of Variations in Their Morphological and Thermal Properties through Changes in Composition of Alkyl-Substituted (ε-DL) and Non-Substituted (ε-CL, EB, L-LA) Monomers.

Three series of polyesters based on monomer combinations of ε-caprolactone (ε-CL), ethylene brassylate (EB), and l-Lactide (LLA) with the alkyl substituted lactone ε-decalactone (ε-DL) were synthesized at different molar ratios. Copolymers were obtained via ring opening polymerization (ROP) employing TBD (1,5,7-triazabicyclo-[4.4.0]-dec-5-ene), an organic catalyst which can be handled under normal conditions, avoiding the use of glove box equipment. The molar monomer composition of resulting copolymers differed from theoretical values due to lower ε-DL reactivity; their Mn and Mw values were up to 14 kDa and 22.8 kDa, respectively, and distributions were (Ɖ) ≤ 2.57. The thermal stability of these materials suffered due to variations in their ε-DL molar content. Thermal transitions such as melting (Tm) and crystallization (Tc) showed a decreasing tendency as ε-DL molar content increased, while glass transition (Tg) exhibited minor changes. It is worth mentioning that changes in monomer composition in these polyesters have a strong impact on their thermal performance, as well as in their crystallization degree. Consequently, variations in their chemical structure may have an effect on hydrolyic degradation rates. It should be noted that, in future research, some of these copolymers will be exposed to hydrolytic degradation experiments, including characterizations of their mechanical properties, to determine their adequacy in potential use in the development of soft medical devices.

Upcycling Polytetrahydrofuran to Polyester

Upcycling Polytetrahydrofuran to Polyester

Stereocomplexation of Stereoregular Aliphatic Polyesters: Change from Amorphous to Semicrystalline Polymers with Single Stereocenter Inversion.

Stereocomplexation is a useful strategy for the enhancement of polymer properties by the co-crystallization of polymer strands with opposed chirality. Yet, with the exception of PLA, stereocomplexes of biodegradable polyesters are relatively underexplored and the relationship between polymer microstructure and stereocomplexation remains to be delineated, especially for copolymers comprising two different chiral monomers. In this work, we resolved the two enantiomers of a non-symmetric chiral anhydride (CPCA) and prepared a series of polyesters from different combinations of racemic and enantiopure epoxides and anhydrides, via metal-catalyzed ring-opening copolymerization (ROCOP). Intriguingly, we found that only specific chiral combinations between the epoxide and anhydride building blocks result in the formation of semicrystalline polymers, with a single stereocenter inversion inducing a change from amorphous to semicrystalline copolymers. Stereocomplexes of the latter were prepared by mixing an equimolar amount of the two enantiomeric copolymers, yielding materials with increased melting temperatures (ca. 20 °C higher) compared to their enantiopure constituents. Following polymer structure optimization, the stereocomplex of one specific copolymer combination exhibits a particularly high melting temperature (Tm = 238 °C).

Bio-Degradable Polyesters with Rigid Cyclic Diester from Camphor and Tartaric Acid.

Despite their excellent, useful, and stable properties, thermoplastics are constantly subject to environmental risks because of their low degradability under thermal, chemical, and mechanical stresses. To overcome the aforementioned issues, we hereby introduce an eco-friendly camphor (Ct) cyclic diester. The Ct diester is designed as a monomer, including a ketal group from the Ct, and shows high thermal stability via a rigid spiro-ring and a bridged bicyclic structure. A series of polyester was synthesized using the Ct diester, including various types of diols and dimethyl terephthalate. PETxCty copolyesters showed appropriate thermal stability up to 414 °C and a high glass transition temperature. This thermal behavior led to amorphous regions as the Ct diester content increased. Regarding the proportion of the Ct diester in the polyester, it was sensitive to hydrolysis and contributed to the degradation of the polyester in acid buffer conditions.Graphical

L‐glutamic acid as a versatile platform for rapid synthesis of functional polyesters via facile Passerini multicomponent polymerization

AbstractIn this work, a series of polyesters with different functional side groups were successfully prepared by Passerini three‐component polymerization (P‐3CP) in “one‐pot” from biorenewable l‐glutamic acid (l‐GA)‐based monomers. First, the polymerization conditions including monomer feed ratios, solvents and comonomer were systematically studied using Boc‐protected l‐GA with adipaldehyde and tert‐butyl isocyanide. Under the optimal polymerization conditions, a variety of N‐substituted l‐GA‐based monomers as well as functional isocyanides were attempted in the P‐3CP to produce polyesters with different functionalities. Moreover, it was found that after removal of pendant protecting groups, the obtained l‐GA‐based polyester degraded spontaneously into small molecules via 1,5‐intramolecular cyclization between the pendant amine groups and the ester groups in polymer backbone. The structures and thermal properties of obtained polymers were determined by 1H NMR, IR, SEC, MALDI‐ToF‐MS, DSC, and TGA measurements. Starting from biorenewable l‐GA, this approach will provide a facile and straightforward route to produce functional and biodegradable polyesters, thus effectively expanding the range of biodegradable polymers.

Assessment of IsPETase-Assisted Depolymerization of Terephthalate Aromatic Polyesters and the Effect of the Thioredoxin Fusion Domain

Terephthalate polyesters such as poly(ethylene terephthalate) (PET) have been massively produced over the last few decades due to their attractive properties in multiple applications. However, due to their limited biodegradability, they have accumulated in landfills and oceans, posing an environmental threat. Enzymatic recycling technologies are predicted to generate long-term socioeconomic benefits. In the present work, we compared the IsPETase (from Ideonella sakaiensis 201-F6) activity on a series of polyesters, including poly(butylene) terephthalate (PBT), poly(hexamethylene) terephthalate (PHT) and Akestra™, with PET. The IsPETase showed remarkable activity toward PET (39% degradation of the original polyester) that was higher than that toward Akestra™ (0.13%), PBT (0.25%) and PHT (0.13%) after 72 h. Thus, based on experimental data and computational analysis, we report insights into IsPETase activity on a series of terephthalate-based polyesters. Aside from that, the fusion domain (Trx) effect in the production and activity of a recombinant Trx-IsPETase is reported.

Phosphorus Ester Containing Mesoporous Silica as Novel High‐Effective Flame Retardant in Polyurethane and Polyester Coatings

AbstractIn this study mesoporous silica spheres (MPSs) and polyphosphoric acid based organophosphate ester flame retardant (FR material) material were synthesized and flame retardancy performance in acrylate‐based polyurethanes (PUR) and polyester (PET) resins investigated. For this, both MPSs and FR material were synthesized according to literature and FR material was loaded into MPSs which takes the role of carrier. Loaded MPSs were put into UV curable PUR and PET resins and polymerized under UV radiation. Their characteristics were investigated by FT‐IR, TGA, LOI, SEM and TEM. The results showed that FR material had excellent flame‐retardant abilities for both PUR and PET series. The TGA curves suggested that synthesized FR material shows lower thermal stability at low temperatures than original materials however it showed good ability of char formation at higher temperatures, therefore improving the flame retardant property of samples. Moreover the LOI analysis showed that flame retardancy properties were improved significantly. The additive increased the LOI value from 20,5 and 21 to 26,5 and 27.

Development of High-Molecular-Weight Fully Renewable Biopolyesters Based on Oxabicyclic Diacid and 2,5-Furandicarboxylic Acid: Promising as Packaging and Medical Materials

Renewable and biodegradable linear polyesters with oxabicyclic units based on the ring-opening polymerization (ROP) have attracted considerable interest as alternatives to petrochemical-based polyesters. However, incorporating bio-based aromatic building blocks into the linear polyesters with oxabicyclic units by the ROP process is limited. Herein, we report three series of oxabicyclic renewable polyesters based on oxabicyclic diacid (OBDA), monomethyl oxabicyclic diacid (MBDA), and oxabicyclic anhydride with dimethyl substituents (d-MBDA) derived from bio-based furanics and synthesized via melt polymerization (MP). The molecular weights of the polyesters obtained from OBDA were significantly higher than those of the reported polyesters based on OBDA anhydride derivatives, leading to significantly higher glass-transition temperature (Tg) values and tensile strength. Furthermore, a series of fully bio-based copolyesters (PBOBmFn) was first obtained via the MP strategy by the incremental replacement of OBDA with bio-based 2,5-furandicarboxylic acid (FDCA). The incorporation of FDCA units significantly improved the thermal stabilities and mechanical properties of the linear polyesters with oxabicyclic units and endowed them with gas barrier properties that were better than those of commercial poly(ethylene terephthalate) (PET). The Tg values of PBOBmFn ranged from 38.8 to 40.8 °C and were comparable with that of the commercial biomedical material Vicryl. Additionally, the trade-off between OBDA and FDCA units can control the fast biodegradation and environmental durability of the PBOBmFn polyester series. PBOBmFn also showed excellent biocompatibility to and was safe for both RAW264.7 and PC12 cells. The strategy of the incorporation of FDCA building blocks via MP enhanced the comprehensive properties of the linear polyesters with oxabicyclic units; moreover, the adjustment between FDCA and OBDA units can be leveraged to control the polyester roles between packaging and biomedical fields while retaining the completely renewable nature of the parent of polyesters.

Bio-Based Polyricinoleate and Polyhydroxystearate: Properties and Evaluation as Viscosity Modifiers for Lubricants

This paper aims to design bio-based polyester as a viscosity modifier for lubricant properties. Bio-based polyricinoleate (PRic) and its saturated homologous polyhydroxystearate (PHS) have been synthesized from fatty acid methyl esters. The polycondensation performed in bulk in a one-step reaction without any purification leads to two series of polyesters within a large range of molecular weights, with Mw between 3 and 130 kg·mol–1. Their thermal properties were investigated. Good thermal stability was observed with degradation temperatures above 300 °C. As expected, PRic appeared to be amorphous with a particularly low glass-transition temperature, while PHS is semicrystalline. A rheological study determined that polyricinoleate entangled when its molecular weight was above 25 kg·mol–1. These two bio-based and biodegradable polymers were then evaluated as viscosity modifiers in both organic and mineral oils. PHS with high molecular weights appeared to be an excellent thickener as well as a good viscosity index improver with a viscosity index (VI) increase above +50 in organic lubricant oil and +64 in mineral oil.

Effective and facile solvent-free synthesis route to novel biobased monomers from vanillic acid: Structure–thermal property relationships of sustainable polyesters

Solvent-free synthesis of monomers is one among the most promising ways to develop greener polymers that are both environmentally and economically acceptable, but it was described as one of the “grand challenges” facing chemists. As a contribution towards sustainable bioplastics development which has attracted great attention in materials science research, a truly efficient, practical, and more environmentally friendly solvent-free synthetic route was successfully applied herein to prepare three new fully biobased diol monomers derived from vanillic acid and aliphatic diols (ethylene glycol, 1,3-propanediol and 1,4-butanediol). Their chemical structures were confirmed in detail by 1H, 13C NMR and FTIR spectroscopies while their thermal properties were investigated by DSC and TGA. Results showed high melting points in the 121.8–142.3 °C range and no significant weight loss (Td, 5%) up to 243, 312 and 284 °C respectively for diols with 2, 3, and 4 methylene units. To prove their suitability in polymerization, melt polycondensation of prepared diols with three diacyl chlorides and also with dimethyl 2,5-furandicarboxylate were successfully carried out under catalyst-free conditions and using tetrabutyl titanate (TBT), respectively. The chemical structures of the novel series of polyesters were confirmed in detail by NMR and FTIR spectroscopies. The latter showed satisfactory intrinsic viscosity values in the 0.25–0.30 dL/g range and a wholly amorphous nature. All materials revealed high thermal stability with onset degradation temperatures Td, 5% ranging from 314 to 373 °C and a wide glass transition temperature (Tg) range oscillating from -2.8 to 69.5 °C. The innovative approach proposed herein for the first time, which involves the synthesis of sustainable monomers under solvent-free conditions, is fully aligned with one of the main principles of green chemistry.

Enzymatic synthesis of biobased polyesters utilizing aromatic diols as the rigid component

In the present work, the biocatalyzed synthesis of a series of aromatic-aliphatic polyesters based on the aliphatic diesters dimethyl succinate, dimethyl adipate and dimethyl sebacate and the aromatic diols 2,5-bis(hydroxymethyl)furan, 3,4-bis(hydroxymethyl)furan and 2,6-pyridinedimethanol were investigated. A similar series of polyesters based on the petroleum-based 1,3-benzenedimethanol, 1,4-benzenedimethanol and 1,4-benzenediethanol were also synthesized for comparison. Data show that the enzymatic syntheses were successful starting from all diols, with the obtained polymers having isolated yields between 67 and over 90%, number average molecular weights between 3000 Da and 5000 Da and degree of polymerization (DP) of 6–18 (based on the used aliphatic diesters and aromatic diols) when polymerized in diphenyl ether as solvent. Only using 3,4-bis(hydroxymethyl)furan as the diol led to shorter oligomers with isolated yields around 50% and DPs of 3–5. DSC and TGA thermal analyses show clear correlation between polymer crystallinity and aliphatic carbon chain length of the diester.

Synthesis and characterization of renewable polyesters based on vanillic acid

AbstractVanillic acid, potentially derived from biosourced feedstocks, was used as starting material in the synthesis of novel polyesters. A diester obtained by esterification and etherification of vanillic acid served as first monomer, in combination with resorcinol bis(2‐hydroxyethyl) ether, hydroquinone bis(2‐hydroxyethyl) ether, or aliphatic diols with different carbon chain lengths as second monomers, and antimony trioxide as catalyst to synthesize a series of polyesters by melt polymerization. The materials obtained had polystyrene‐equivalent M n = 10,000–19,500 g/mol and M w = 19,300–39,500 g/mol. Thermal analysis yielded melting temperatures of 76–114°C and onset decomposition temperatures T5% = 321–360°C. Dynamic mechanical and tensile testing confirmed that polyesters derived from vanillic acid have properties superior to poly(ethylene terephthalate) (PET). Aqueous degradation experiments with bulk polyester samples at different pH over 16 weeks led to intrinsic viscosity decreases of 9–23% under neutral conditions (pH 7), 10–26% under acidic conditions (pH 3), and 7–19% under alkaline conditions (pH 12). The results obtained show that the good thermal stability and degradability of vanillic acid‐based polyesters, and the tunability of the properties of these materials through selection of the diol monomer used in their synthesis, make them excellent biosourced replacements for commercial polyesters such as PET.

High thermal conductivity and excellent flexibility of crystalline polyesters with flexible segments in main chains

Thermal conductivity (TC) of polymers can be enhanced by incorporating rigid conjugated structures, which will result in sacrifice of other characteristics such as flexibility. To deal with such problem, a series of polyesters (PEmC) with long methylene units in main chains were synthesized by polycondensation and transesterification. A sharp increment of 219.7% in TC was observed and the maximum TC reached to 0.227 Wm−1 K−1, which is twice that of traditional thermoplastic. It is intriguing that thermal diffusivity for above samples changed few while specific heat capacity of PEmC increased from 0.620 J g−1 K−1 to 1.470 J g−1 K−1 on elongating the length of flexible methylene segments in main chains. Thus TC in this system was mainly enhanced by enhancing specific heat capacity. Due to flexible segments in main chains, Young modulus of PEmC (around 0.2 GPa) is one order of magnitude lower than that of conventional thermoplastic. Moreover, PEmC exhibited good performance both in maintaining flexibility below glass-transition temperature and preserving modulus above glass-transition temperature, which might be remarkable in potential application for flexible electronics.

Copolymerization of Natural Camphor-Derived Rigid Diol with Various Dicarboxylic Acids: Access to Biobased Polyesters with Various Properties.

In this work, alicyclic (1R,3S)-1,2,2-trimethylcyclopentane-1,3-dimethanol (TCDM), derived from natural camphor, was copolymerized with linear α,ω-diacids, terephthalic acid (TPA), and 2,5-furandicarboxylic acid (FDCA), affording a series of polyesters with functional properties. 2D NMR spectroscopy revealed that the stereoconfiguration of TCDM was preserved after polymerization. The TCDM polyester based on TPA showed high thermostability, high Tg value (115 °C), high modulus (1.3 GPa), and high ultimate strength (29.8 MPa). The TCDM polyester based on 1,4-succinic acid exhibited excellent ductility and resilience. Lastly, the rigidity analysis based on van Krevelen's group contribution method, coupled with the comparisons between TCDM- and sugar-based polyesters, confirmed that TCDM is a highly reactive and rigid diol. Results indicate that TCDM polyesters are suitable for a wide range of applications, including hot-filled containers and transparent packaging materials. This work addresses some critical needs for high performance biopolymers such as achieving high Tg values, high thermostability, and high transparency.

Improving the Hydrolysis Rate of the Renewable Poly(hexamethylene sebacate) Through Copolymerization of a Bis(pyrrolidone)-Based Dicarboxylic Acid.

In this work, we report on the synthesis of a series of polyesters based on 1,6-hexanediol, sebacic acid, and N,N’-dimethylene-bis(pyrrolidone-4-carboxylic acid) (BP-C2), of which the latter is derived from renewable itaconic acid and 1,2-ethanediamine. Copolymers with a varying amount of BP-C2 as dicarboxylic acid are synthesized using a melt-polycondensation reaction with the aim of controlling the hydrolysis rate of the polymers in water or under bioactive conditions. We demonstrate that the introduction of BP-C2 in the polymer backbone does not limit the molecular weight build-up, as polymers with a weight average molecular weight close to 20 kg/mol and higher are obtained. Additionally, as the BP-C2 moiety is excluded from the crystal structure of poly(hexamethylene sebacate), the increase in BP-C2 concentration effectively results in a suppression in both melting temperature and crystallinity of the polymers. Overall, we demonstrate that the BP-C2 moiety enhances the polymer’s affinity to water, effectively improving the water uptake and rate of hydrolysis, both in demineralized water and in the presence of a protease from Bacillus licheniformis.