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This work explores for the first time the enzymatic synthesis of poly(butylene-co-e-caprolactone) (PBSCL) copolyesters in bulk using commercially available monomers (dimethyl succinate (DMS), 1,4-butanediol (BD), and e-caprolactone (CL)). A preliminary kinetic study was carried out which demonstrated the higher reactivity of DMS over CL in the condensation/ring opening polymerization reaction, catalyzed by Candida antarctica lipase B. PBSCL copolyesters were obtained with high molecular weights and a random microstructure, as determined by 13C NMR. They were thermally stable up to 300 °C, with thermal stability increasing with the content of CL in the copolyester. All of them were semicrystalline, with melting temperatures and enthalpies decreasing up to the eutectic point observed at intermediate compositions, and glass transition temperatures decreasing with the content of CL in the copolyester. The use of CALB provided copolyesters free from toxic metallic catalyst, which is very useful if the polymer is intended to be used for biomedical applications. Peer Reviewed Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles

Poly(ethylene terephthalate) (PET), known for its clarity, food safety, toughness, and barrier properties, is a preferred polymer for rigid packaging applications. PET is also one of the most recycled polymers worldwide. In light of climate change, significant efforts are underway to improve the carbon footprint of PET by synthesizing it from bio-based feedstocks. Often times, specific applications demand PET to be copolymerized with other monomers. This work focuses on copolymerization of PET with a bio-based co-monomer, 2,5-furandicarboxylic acid (FDCA) to produce the copolyester (PETF). We report the multifunction of FDCA to influence the esterification reaction kinetics and the depolymerization kinetics (via alkaline hydrolysis) of the copolyester PETF. NMR spectroscopy and titrimetric studies revealed that copolymerization of PET with different levels of FDCA improved the esterification reaction kinetics by enhancing the solubility of monomers. During the alkaline hydrolysis, the presence of FDCA units in the backbone almost doubled the PET conversion and monomer yield. Based on these findings, it is demonstrated that the FDCA facilitates the esterification, as well as depolymerization of PET, and potentially enables reduction of reaction temperatures or shortened reaction times to improve the carbon footprint of the PET synthesis and depolymerization process.

In the present paper, many unsaturated polyesters has been synthesized using maleic anhydride, phthalic anhydride and succinic anhydride for esterification with new monomer [E)-1-(4-hydroxyphenyl)-3-(3-methoxy-4-hydroxyphenyl) prop-2-en-1-one]. These polyesters were polymerized by condensation reaction . Their chemical structures were characterized using FTIR, 13C-NMR and 1H NMR spectroscopy. Thermal properties have been analysed using Differential Scanning Calorimetry of synthesized polyesters All the polymers showed well thermal stability and perfect data of glass transition temperature (Tg) also the results showed polyesters and monomer were successfully synthesized by giving well spectrum improved existing an ester functional group (-COO-) in spectrums each polymer prepared also existent Chalcone functional group(-CO-CH=CH-) in spectrum of monomer.

Synthesizing different types of sequence-controlled copolyesters can enrich the diversity of copolyesters and modify their properties more precisely, but it is still a challenge to synthesize a complicated sequence-controlled copolyester using different hydroxy acids in a living polymerization manner. In this work, a highly regioselective and stereoselective catalytic system was developed to synthesize biorenewable and biodegradable copolyesters of mandelic acid and lactic acid with isotactic-alternating, heterotactic-alternating, and ABAA-type precise and complicated sequences. Because of the regular incorporation of mandelic acid into polylactide, these sequence-controlled copolymers of mandelic acid and lactic acid show higher glass-transition temperatures than polylactide and a random copolymer. A stereocomplexation interaction between two opposite enantiomeric isotactic polymer chains was also discovered in the isotactic-alternating copolymer.

In this study, an unsaturated copolyester, poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxy-10-undecenoate] (PHBU), was produced by an engineered strain of Escherichia coli, cross-linked via thiol-ene click chemistry, and analyzed for improved physical properties and biocompatibility with human mesenchymal stem cells. By cross-linking the PHBU polymer, an increase in tensile strength of greater than 200% to 26.2 MPa was observed, resulting in a material with physical properties closer to those relevant for soft tissue replacement. Results showed that this chemically cross-linked polyester did not exhibit significant cytotoxicity toward human cells after chemical modification. The chemically modifiable copolyester described here could potentially be used as a replacement for an assortment of tissues currently without viable material alternatives in the field of tissue-engineering.

[EN] ZnO compounds exert a catalytic effect on the degradation of polyesters and could affect the biodegradability of such polymers. Herein, composites of 2 wt% of ZnO particles and biodegradable commercial Ecovio polymer, a blend of poly(lactic acid) (PLA) and a copolyester, are prepared by melt extrusion process to further study the effect of the incorporation of ZnO particles on the biodegradability of this polyester under composting conditions. Different nano- and micro-sized ZnO particles are employed to investigate the effect of the size, morphology, and surface charge of ZnO on the physicochemical properties of the polymeric composite and nanocomposite by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA). The influence of such compounds on the compost disintegradability is further investigated by different techniques including, gel permeation chromatography (GPC), confocal Raman microscopy and energy dispersive x-ray spectrometer (EDX). The results demonstrate that the ZnO particles significantly accelerate the disintegration process of the Ecovio polymeric blend under a composting environment., This research was funded by the MICINN under the projects PID2019–10460 0RB-I0 0 and MAT2017–86450-C4–1-R , the Spanish National Research Council (CSIC) under the project NANOMIND CSIC 201560E068 , the Agencia Estatal de Investigación (AEI, Spain), and Fondo Europeo de Desarrollo Regional (FEDER, EU). F.R-M is indebted to MINECO for a ‘Ramon y Cajal’ contract (ref: RyC-2015–18626), which is co-financed by the European Social Fund . F.R-M also acknowledges support from a 2018 Leonardo Grant for Re- searchers and Cultural Creators (BBVA Foundation).

Big spherulite structure and high crystallinity are the two main drawbacks of poly(butylene succinate) (PBS) and hinder its application. In this work, a new type of copolyester poly(butylene succinate-co-butylene acetylenedicarboxylate) (PBSAD) is synthesized. With the incorporation of acetylenedicarboxylate (AD) units into PBS chains, the crystallization temperature and crystallinity are depressed by excluding AD units to the amorphous region. In contrast, the primary nucleation capability is significantly strengthened, without changing the crystal modification or crystallization kinetics, leading to the recovery of total crystallization rate of PBSAD under the same supercooling condition. The existence of specific interaction among AD units is found to be crucial. Although it is too weak to contribute to the melt memory effect at elevated temperature, the interaction continuously strengthens as the temperature falls down, and the heterogeneous aggregation of AD units keeps growing. When the aggregating process reaches a certain extent, it will induce the formation of a significant amount of crystal nuclei. The unveiled nucleation mechanism helps to design PBS copolymer with good performance.

The friction and wear (adhesive and abrasive wear modes) behavior of thermoplastic compounds is a multifaceted procedure, intensely pretentious by strand and special filler properties as well as operational conditions. This chapter reveals the tribological execution of small glass strand (SGF)-reinforced thermoplastic copolyester elastomer (TCE) compounds filled with both micro- (polytetrafluroethylene, silicon carbide, aluminum oxide, and molybdenum disulfide) and nanosized (aluminum oxide and perflouropolyether) special space grouts. Two-body abrasive wear (single-pass and multipass conditions) test results showed that TCE packed with PTFE space filler exhibited superior resistance to abrasion. Three-body abrasive wear data revealed that the specific wear rate (Ks) diminished with an increase in the grazing distance and increased with an upsurge in silica sand particle size. Dry sliding wear test results revealed that a TCE crossbreed compound fortified with SGF and filled with PTFE, SiC, Al2O3, and MoS2 particulates exhibited improved resistance to attrition. On the other hand, a TCE crossbreed compound filled with perfloropolyether (PFPE) nanofiller demonstrated the lowest friction coefficient in the study group. Decisively, the worn faces of the chosen wear-tested specimens were assessed using a scanning electron microscope to distinguish the involved attrition mechanisms.

A biodegradable copolyester, poly(butylene succinate-co-ε-caprolactone) (PBS_CL), was used for first time as an excipient for pharmaceutical dosage forms using direct compression and hot processing techniques (ultrasound-assisted compression (USAC) and hot melt extrusion (HME)). Robust binary systems were achieved with hot processing techniques, allowing a controlled release of the drug. With only 12% v/v of PBS_CL, controlled release forms were obtained using USAC whereas in HME over 34% v/v of excipient is necessary. Amounts over 23% v/v allowed a long-extended release for more than 72 h following diffusional kinetic. Thanks to the high melting point of theophylline and the physicochemical properties of PBS_CL selected and synthesized, the structure of the excipient inside the USAC tablets and HME filaments corresponds to a continuum medium. A percolation threshold around 23% v/v was estimated, which agrees with a continuum percolation model. The polymer shows a high excipient efficiency value using HME and USAC. A nanostructured matrix with wall thicknesses lower than 0.1 µm was obtained. This leads to a very effective coating of the drug particles by the excipient, providing a slow and reproducible release. The present study therefore supports the use of PBS_CL, for the preparation of controlled release dosage forms using hot processing techniques Ministerio de Economía y Competitividad MAT2016-77345-C3-3-P Ministerio de Ciencia, Innovación y Universidades RTI2018-095041-B-C31, RTI2018-095041-B-C33

In the field of artificial prostheses for damaged vessel replacement, polymeric scaffolds showing the right combination of mechanical performance, biocompatibility, and biodegradability are still demanded. In the present work, poly(butylene-co-triethylene trans-1,4-cyclohexanedicarboxylate), a biodegradable random aliphatic copolyester, has been synthesized and electrospun in form of aligned and random fibers properly designed for vascular applications. The obtained materials were analyzed through tensile and dynamic-mechanical tests, the latter performed under conditions simulating the mechanical contraction of vascular tissue. Furthermore, the in vitro biological characterization, in terms of hemocompatibility and cytocompatibility in static and dynamic conditions, was also carried out. The mechanical properties of the investigated scaffolds fit within the range of physiological properties for medium- and small-caliber blood vessels, and the aligned scaffolds displayed a strain-stiffening behavior typical of the blood vessels. Furthermore, all the produced scaffolds showed constant storage and loss moduli in the investigated timeframe (24 h), demonstrating the stability of the scaffolds under the applied conditions of mechanical deformation. The biological characterization highlighted that the mats showed high hemocompatibility and low probability of thrombus formation, finally, the cytocompatibility tests demonstrated that cyclic stretch of electrospun fibers increased endothelial cell activity and proliferation, in particular on aligned scaffolds.

Tribology (which is the study of friction, wear, and lubrication) has emerged as one of the fields that contribute to sustainable development through environmentally friendly solutions. These solutions are aimed to reduce energy consumption by lowering power losses during sliding applications. Power losses at sliding interfaces can be diminished by reducing the abrasive and adhesive nature of hard metal asperity interactions. One way to reduce friction losses is using high-performance polymer coatings (HPPCs) as interacting (sliding) surfaces (tribopairs). It has been shown that HPPCs based on polyether ether ketone (PEEK), polytet- rafluoroethylene (PTFE), and aromatic thermosetting copolyester (ATSP) blended with solid lubricants can withstand high bearing loads and provide self-lubrication. High-Performance Polymer (HPP) Blends. Thermal Properties of Polymer Coatings. Micro-/Nanoindentation and Micro-/Nanoscratch Techniques. Micromechanical Properties of HPPCs. Correlation of Micromechanical Properties with Microstructure Primera edición

Considering the rising demand to diminish energy consumption and CO2 emissions, the biobased segmented block copolymer, poly(butylene succinate-co-dilinoleic succinate) (PBS-DLS) with 70:30 (wt %) ratio of hard to soft segments was obtain using Candida antarctica lipase B (CAL-B) as a biocatalyst. Throughout two-step synthesis in diphenyl ether, biobased diethyl succinate was polymerized with renewable 1,4–butanediol and dimer linoleic diol to obtain “green” copolyester as a sustainable alternative to petroleum-based materials. Proton nuclear magnetic resonance (1H NMR) analysis confirmed that, using enzyme as a catalyst, we were able to produce multiblock copolymer and gel permeation chromatography (GPC) measurements revealed number-averaged molecular mass to be 25,000 g/mol. Additionally, differential scanning calorimetry (DSC) analysis revealed low-temperature glass transition (Tg) of soft segments and high melting point (Tm) of hard segments which indicate on two-phase morphology. Furthermore, cytotoxicity test using L929 murine fibroblasts was conducted on extracts of obtained PBS-DLS copolymer, indicating excellent biocompatibility in vitro.

This research synthesizes novel copolyester (PCITN) containing biobased isosorbide, 1,4-cyclohexandimethanol, terephthalic acid, and 2,6-naphthalene dicarboxylic acid and characterize its properties. The PCITN copolyester was extruded into film, and its performance properties including: tensile strength, Young&rsquo, s modulus, thermal, dimensional stability, barrier (water barrier), and optical (birefringence and transmittance) were analyzed after uniaxial stretching. The films have higher Tg, Tm, dimensional stability, and mechanical properties than other polyester-type polymers, and these performance properties are significantly increased with increasing stretching. This is due to the increased orientation of molecular chains inside the films, which was confirmed by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and birefringence results. Good water barrier (0.54%) and lower birefringence (△n: 0.09) of PCITN film compared to poly(ethylene terephthalate) (PET), poly(ethylene 2,6-naphthalate) (PEN), and polyimide (PI) films, used as conventional substrate materials for optical devices, make it an ideal candidate as performance material for next-generation flexible devices.

In this study, poly(butylene sebacate-co-terephthalate) (PBSeT) was successfully synthesized using various ratios of sebacic acid (Se) and dimethyl terephthalate (DMT). The synthesized PBSeT showed a high molecular weight (Mw, 88,700&ndash, 154,900 g/mol) and good elastomeric properties. In particular, the PBSeT64 (6:4 sebacic acid/dimethyl terephthalate mole ratio) sample showed an elongation at break value of over 1600%. However, further increasing the DMT content decreased the elongation properties but increased the tensile strength due to the inherent strength of the aromatic unit. The melting point and crystallization temperature were difficult to observe in PBSeT64, indicating that an amorphous copolyester was formed at this mole ratio. Interestingly, wide angle X-ray diffraction (WAXD) curves was shown in the cases of PBSeT46 and PBSeT64, neither the crystal peaks of PBSe nor those of poly(butylene terephthalate) (PBT) are observed, that is, PBSeT64 showed an amorphous form with low crystallinity. The Fourier-transform infrared (FT-IR) spectrum showed C&ndash, H peaks at around 2900 cm&minus, 1 that reduced as the DMT ratio was increased. Nuclear magnetic resonance (NMR) showed well-resolved peaks split by coupling with the sebacate and DMT moieties. These results highlight that elastomeric PBSeT with high molecular weight could be synthesized by applying DMT monomer and showed promising mechanical properties.

Structural, thermal and mechanical properties of the compostable composites comprising a biodegradable aliphatic-aromatic copolyester (namely, the poly(butylene adipate-co-terephthalate; PBAT), and microcrystalline cellulose (MCC) derived from agricultural waste, the wheat stalk, were investigated. Purely physical interaction between the components was found to be responsible to get the MCC phase quite uniformly embedded in the PBAT matrix, the latter being the dominating component of the composites surface. There were two distinct thermally activated degradation regimes characterized by separate activation processes corresponding to the decomposition of the MCC and the PBAT phases, respectively. The physically bound and rather weak but large PBAT-MCC interfacial areas provoked more rapid thermal degradation of the composites compared to the pure components. While the PBAT acted as a highly ductile material upon tensile loading, the composites maintained high ductility only up to 20% by weight of the MCC. The drastic reduction in the ductility for higher filler loading was attributed to the possible void formation at the interfacial region followed by crack initiation and propagation leading eventually to the premature specimen fracture. The composite materials thus fabricated were hence found to suit for low-load bearing applications.

Bio-based unsaturated poly(butylene adipate-co-butylene itaconate) (PBABI) aliphatic copolyesters were synthesized with pentaerythritol (PE) as a modifier, observing the melting point, crystallization, and glass transition temperatures were decreased from 59.5 to 19.5 °C and 28.2 to −9.1 °C as an increase of itaconate concentration, and Tg ranged from −54.6 to −48.1 °C. PBABI copolyesters tend to the amorphous state by the existence of the BI unit above 40 mol%. The yield strength, elongation, and Young’s modulus at different BA/BI ratios were valued in a range of 13.2–13.8 MPa, 575.2–838.5%, and 65.1–83.8 MPa, respectively. Shear-thinning behavior was obtained in all BA/BI ratios of PBABI copolyesters around an angular frequency range of 20–30 rad s−1. Furthermore, the thermal and mechanical properties of PBABI copolyesters can be well regulated via controlling the itaconic acid contents and adding the modifier. PBABI copolyesters can be coated on a 3D air mesh polyester fabric to reinforce the mechanical property for replacing traditional plaster applications.

In recent years, a significant progress has been made in the development and study of nanoparticles aimed at biomedical applications. Polymer systems are believed to be an interesting perspective in this direction, because they can be designed as multifunctional systems for drug delivery and release, as well as they can provide information about their location using fluorescence spectroscopy methods. The nanoparticles get directly into the bloodstream through intravenous injections. In most cases, the first molecules which they interact are proteins, which are one of the main constituents of the human body and the driving force of most biological processes. Therefore, understanding the interaction between nanoparticles and proteins is important for the safe and effective use of nanoparticles. In this regard, changes in the properties of nanoparticles after interaction with albumin have been analyzed and it has been shown that albumin, depending on the structure of the amphiphilic copolyester, either acts as an additional stabilizer of nanoparticles dispersed phase or leads to partial aggregation. At the same time, the albumin layer slightly affects the characteristics of biodistribution and the hydrolytic properties of the obtained amphiphilic copolyesters with fluorescent moieties.

A molecular-level understanding of ion and polymer dynamics in imidazolium–poly(ethylene glycol) (PEG) copolyester ionomers having different counteranions [PF6– vs (CF3SO2)2N–], alkylene spacer len...

The hydrophilic copolyester polyethylene terephthalate (PET) (ENCDP-X) was successfully synthesized by chemical modification consisting of copolymerization and blending and the comonomers, including sodium isophthalate-5-sulfonate (SIPE), polyethylene glycol (PEG), 2,2-dimethyl-1,3-propanediol (NPG) and matting agent TiO2 with different content. Moreover, the structural characterization of sequential structure, crystallization and thermal properties were studied. The results showed that the comonomers were successfully embedded in the copolyester, the actual molar ratio in the copolyester was consistent with the relative feed ratio and the degree of randomness was calculated to be 0.99, showing that the random copolymers synthesized during the melt polycondensation process and the chemical structure was roughly consistent with the expected molecular chain sequence structure. The thermal parameters of the modified copolyester, containing the glass transition temperature (Tg), melting point (Tm), crystallinity (Xc) and thermal degradation temperature, were decreased, and the cold crystallization temperature (Tc) was increased. In addition, with the increasing of the TiO2 content, it improves the thermal performance of the copolyester and it is beneficial to processing and application. The above conclusion is further verified by non-isothermal kinetic analysis. In addition, the copolyester exhibited the better hydrophilicity than pure PET.

© 2020 by the authors., In the present study, poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] was reinforced with hydroxyapatite nanoparticles (nHA) to produce novel nanocomposites for potential uses in bone reconstruction. Contents of nHA in the 2.5–20 wt % range were incorporated into P(3HB-co-3HHx) by melt compounding and the resulting pellets were shaped into parts by injection molding. The addition of nHA improved the mechanical strength and the thermomechanical resistance of the microbial copolyester parts. In particular, the addition of 20 wt % of nHA increased the tensile (Et) and flexural (Ef) moduli by approximately 64% and 61%, respectively. At the highest contents, however, the nanoparticles tended to agglomerate, and the ductility, toughness, and thermal stability of the parts also declined. The P(3HB-co-3HHx) parts filled with nHA contents of up to 10 wt % matched more closely the mechanical properties of the native bone in terms of strength and ductility when compared with metal alloys and other biopolymers used in bone tissue engineering. This fact, in combination with their biocompatibility, enables the development of nanocomposite parts to be applied as low-stress implantable devices that can promote bone reconstruction and be reabsorbed into the human body., This research work was funded by the Spanish Ministry of Science and Innovation (MICI) project numbers RTI2018-097249-B-C21 and MAT2017-84909-C2-2-R and the POLISABIO program with grant number 2019-A02.

Shape memory polymers are of great interest for biomedical applications. However, most stimuli used to trigger shape memory processes, including heat, light, electricity, magnetism, and pH are inconvenient and maybe harmful to the body. Here, we designed and fabricated a new shape memory porous scaffold using biocompatible and readily available water as the trigger. This scaffold was based on poly(fumaricacid-co-1,7-octadiene diepoxide-co-terephthalic acid) (PFOT) synthesized via epoxide ring-opening polymerization in one step. The PFOT scaffold promoted the adhesion, spreading, proliferation and function of cardiomyoblast H9C2 cells in a manner comparable to that for the poly(lactic-co-glycolic acid) scaffold. It exhibited an excellent water-responsive shape memory effect with a fixity and recovery ratio >97% and a shape-recovery process of several minutes, suitable for surgery. In addition, the PFOT scaffold presented good in vitro biodegradation. More importantly, PFOT contains extensive free hydroxyl ...

Semicrystalline polymers generally undergo polymorphic crystal transition and lamellae structural changes during stretching deformation. Such stretch-induced multilevel microstructural evolutions a...

Biobased dihydroxy-terminated aliphatic copolyesters were synthesized from melt-polycondensation of 1,6-adipic acid with 1,6-hexanediol and 1,10-decanediol. The isodimorphic behavior of the copolyesters was explored to identify the pseudo-eutectic copolyester, which was selected as macro-initiator for ring opening polymerization of l -lactide to prepare poly( l -lactide)-b-poly(hexamethylene-co-decamethylene adipate)-b-poly( l -lactide) (PLLA-b-PHDA-b-PLLA) triblock copolymers varying PLLA block length. The blocky structure was confirmed by GPC and NMR, and the influence of PLLA block length on physical and mechanical properties was investigated. Impact testing showed that the impressive impact strength was achieved, that is, the values of PLLA10-PHDA-PLLA10 and PLLA20-PHDA-PLLA20 were largely enhanced to 357.2 J/m and 259.6 J/m, respectively, about 9–12 times greater than that of PLLA homopolymer (28.6 J/m). SEM micrographs of impact fractured surface showed that the triblock copolymers underwent a transition from brittle fracture of neat PLLA to ductile fracture, which is attributed to the introduction of flexible aliphatic polyester as middle soft building block of triblcok copolymers. This work demonstrated isodimorphic aliphatic copolyesters as midblock of PLLA-based triblock fully biobased biodegradable copolymers towards highly toughened PLLA material.

Herein, two fully renewable copolyester series, namely poly(pentylene 2,5-furandicarboxylate-co-caprolactone) (PPeCFs) and poly(hexamethylene 2,5-furandicarboxylate-co-caprolactone) (PHeCFs) were successfully synthesized with combining e-caprolactone (CL) with poly(pentylene 2,5-furandicarboxylate) (PPeF) and poly(hexamethylene 2,5-furan dicarboxylate) (PHeF) with different molar ratios. These materials, with a CL content ranging from 10 to 50 mol%, were synthesized for first time using stannous octoate as catalyst via ring opening polymerization (ROP). Their chemical structures and molar composition were evaluated by 1H NMR, 13C NMR and FTIR spectroscopies, while their thermal properties were investigated in detail using Fast Scanning Calorimetry (FSC), Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA). The obtained results, in combination with Wide-Angle-X-ray diffractometry (WAXD), showed that copolymerization of CL with PHeF and PPeF led to semi-crystalline and partially amorphous copolyesters respectively, providing the basis for significant thermal properties enhancement with respect to the polycaprolactone (PCL) homopolymer, and therefore a much wider range of melting points (Tm) and glass transition temperatures (Tg) were obtained. TGA of the new copolymers showed excellent thermal stability, exceeding 310 °C and 360 °C for PHeCFs and PPeCFs respectively, while their decomposition mechanism was evaluated by pyrolysis-gas chromatography/mass spectroscopy (Py-GC/MS). Almost all copolyesters and mainly the ones with 40 and 50 mol% CL content showed accelerated enzymatic hydrolysis rate.

As an essential biodegradable polyester species, poly(butylene succinate) (PBS) is restricted for wider applications due to its low thermal/mechanical properties and unsatisfactory (bio)degradability. Current practice of introducing either stiff or flexible building blocks into PBS main chains remains challenging to achieve a synergistic enhancement of the thermal and (bio)degradability of this material. We herewith report a series of PBS copolyesters based on the carbohydrate-derived isosorbide (1,4:3,6-dianhydro-D-glucidol, IS) (PBIS) by utilizing its unique intrinsic characters of being rigid and hydrophilic. The target copolyesters were constructed with a broad scope of IS content (0–100 mol%) and with random microstructures. The Mn values and the intrinsic viscosities of these polyesters are in the scopes of 7300–38,700 g mol−1 and 0.33–0.82 dL g−1, respectively. The results shown in this work clearly demonstrated that the presence of IS enhances the Tg values almost linearly and simultaneously promotes (neutral, acidic) hydrolytic and enzymatic degradations (with porcine pancreas) of the copolyesters. PBIS copolyester containing 20 mol% IS displays comparable hydrolytic and enzymatic degradation rates with those of PBSA (20 mol% adipic acid), but a substantially 23 °C higher Tg value. Detailed characterization of the molecular structures, micro-sequential structures, molecular weights and polydipersities, thermal properties, hydrophilicities and (bio)degradability are provided. The (bio)degradation and degradation mechanism study of these copolyesters are reported for the first time.

Unsaturated poly (butylene adipate-co-butylene itaconate) (PBABI) copolyesters were synthesized through melt polymerization composed of 1,4-butanediol (BDO), adipic acid (AA), itaconic acid (IA) and 1,2,4,5-benzenetetracarboxylic acid (BTCA) as a cross-linking modifier. The melting point, crystallization and glass transition temperature of the PBABI copolyesters were detected around 29.8&ndash, 49 &deg, C, 7.2&ndash, 29 &deg, C and &minus, 51.1 and &minus, 58.1 &deg, C, respectively. Young&rsquo, s modulus can be modified via partial cross-linking by BTCA in the presence of IA, ranging between 32.19&ndash, 168.45 MPa. Non-isothermal crystallization kinetics were carried out to explore the crystallization behavior, revealing the highest crystallization rate was placed in the BA/BI = 90/10 at a given molecular weight. Furthermore, the thermal, mechanical properties, and crystallization rate of PBABI copolyesters can be tuned through the adjustment of BTCA and IA concentrations.

To improve the mechanical properties of bio-based poly(ethylene succinate), the sugar monomer isosorbide, which is relatively easy to obtain, was used as a copolymerized third monomer to synthesize poly(ethylene-co-isosorbide succinate), a 100% biomass copolyester. The effects of isosorbide on the crystallinity and thermal properties of copolyester were studied by nuclear magnetic resonance( 1H NMR), differential scanning calorimeter( DSC), and thermogravimetric(TG). Owing to its distinct rigid bicyclic structure, isosorbide can improve the glass transition temperature of the copolyester and decrease the crystallization rate, as well as accelerate the hydrol ysis of the copolyester. Simultaneously, the introduction of isosorbide can effectively improve the antistatic properties of copolyester.

We modified poly(butylene succinate) (PBS) with sugar-based monomer isosorbide to improve the bond strength between PBS and metal interfaces and thereby alleviate the environmental problems caused by nondegradable hot-melt adhesives. We analyzed the efficiency of different catalysts in the synthesis of poly(butylene-co-isosorbide succinate) (PBIS) copolyesters. The thermal stability, thermodynamic characteristics, and melting viscosity of PBIS copolyesters were systematically evaluated by characterization. The results indicate that isosorbide can greatly improve the bond strength of the interface between PBS and the iron plate when copolyesters are used as hot-melt adhesives.

Pristine poly(butylene adipate-co-terephthalate) (PBAT) is a biodegradable aliphatic-aromatic copolyester that shows no photoluminescent features. The radio induction of photoluminescence (PL) properties in PBAT, after exposure to high doses of gamma radiation, was firstly reported in 2014. These new PL properties have great potential for applications at “in vitro” imaging of human cancer, bio-imaging devices and radiation dosimetry. In this paper, we report the radio induction of photoluminescence (PL) properties in PBAT, after exposure to low energy UV irradiation. In this investigation, films of PBAT, produced by the wire-bar coating technique, were exposed to UV radiation for periods of time ranging from 50 to 500 hours. The PL emission analysis revealed that UV irradiation performed under O2 rich air atmosphere enhances the PL output when compared to irradiations performed in the air. FTIR data confirm that the mechanism behind the UV photo-induction of PL features are similar to the mechanism suggested for gamma radio-induction PL emission. The PL intensity x Spectral Irradiance relationship and RGB color components, the green (G) and blue (B) components, can be used to perform 2D UV dosimetry. The high quantum yield emission of UV-induced PL near 500 nm observed in PBAT is a very interesting finding because it involves the development of a new cheap biodegradable photoluminescent polymer that finds application in drug delivery, bio-imaging devices and also in 2D dosimetry.

Aromatic copolyesters, derived from bio-based nipagin and eugenol, were synthesized with renewable 1,6-hexandiol as the spacer. Number-average, weight-average molecular weights (Mn, Mw), and polydispersity (D) values were determined by size exclusion chromatography (SEC). Chemical structures were confirmed by 1H NMR and 13C NMR spectroscopies. Chemical microstructure analysis suggested that the nipagin and eugenol-derived units were inserted into polymer chains in an arbitrary manner. Due to the short chain of 1,6-hexanediol, the splitting of magnetically different methylene carbons, adjacent to the alcohol-oxygens, proved to be more sensitive towards sequence distributions, at the dyed level, than those from 1,10-decanediol. Thermal gravimetric analysis (TGA) demonstrated that these polyester materials have excellent thermal stability (&gt, 360 &deg, C), regardless of the content of eugenol-derived composition incorporated. Differential scanning calorimetric (DSC) and wide-angle X-ray diffraction (WXRD) experiments revealed the semicrystalline nature for this kind of copolyesters. The crystallinities gradually decreased with the increase of eugenol-derived composition. Thermal and crystalline properties were well discussed from the microscopic perspective. The point of this work lies in establishing guidance for future design and modification of high-performance polymer materials from the microscopic perspective.

4,4′-biphenyl dicarboxylate modified poly(ethylene terephthalate) (PET) copolyester molecules proximate to glass fiber surfaces in composites are shown to self-order into a liquid crystalline state. Near the glass fiber surfaces, the polymer chains are proposed to align and form more ordered domains increasing translational entropy, which leads to an overall increase in entropy of the system. The frustrated liquid crystalline polymer of this study, when confined near glass fiber surfaces, became more easily ordered, an example of the concept know as “order through entropy”. Solid-phase birefringence, lower molten-phase viscosity and storage modulus were observed and discussed as properties of these new systems. Such glass fiber reinforced PETBB55 composites possess enhanced mechanical and processing properties, a unique combination.

Poly(ethylene 2,5-furandicarboxylate) (PEF) is a biobased polyester characterized by high gas barrier properties as well as high tensile modulus and strength, but poor toughness. Toughening PEF without sacrificing its modulus, strength and gas barrier performance is a great challenge for PEF modification. In this study, high molecular weight random poly(ethylene- co-1,5-pentylene 2,5-furandicarboxylate)s (PEPeFs) were synthesized via melt copolycondensation of 2,5-furandicarboxylic acid (FDCA), ethylene glycol (EG) and 1,5-pentanediol (PeDO), a cheap, biobased and commercially available odd-carbon comonomer. The synthesized PEPeFs were characterized and assessed with intrinsic viscosity, ATR-FTIR, 1H NMR, DSC, TGA and tensile, impact and O2 permeation test. Mayo-Lewis equation with "reactivity ratio" of 3.78 for PeDO and 0.75 for EG could be used as an empirical equation to correlate the copolyester composition (ϕPeF) with monomer composition. PEPeFs proved nearly amorphous copolyesters having excellent thermal stability. Brittle-ductile transition was achieved at ϕPeF as low as 9 mol %. Increasing ϕPeF led to increase in elongation at break and notch impact strength and decrease in Tg, O2 barrier performance and tensile modulus and strength. However, in comparison with PEF, PEF-rich PEPeFs (ϕPeF 9-47%) not only showed greatly improved elongation at break (29-265% vs 4%) and enhanced impact strength (2.2-3.9 kJ/m2) but also retained very high Young's modulus (2.8-3.3 vs 3.3 GPa) and yielding strength (72-83 vs 82 MPa). Particularly, when compared with bottle-grade PET, PE82Pe18F possesses equal Tg (ca. 75 °C) and comparable elongation at break (ca. 115%), but greatly improved yielding strength (83 MPa) and O2 gas barrier property (4.8 times). As modified PEF materials possessing superior thermo-mechanical and O2 gas barrier properties, these integrally biobased copolyesters may find practical applications in eco-packaging and other fields.

To investigate whether dendritic superstructures can be formed from random copolymers, the morphological evolution of a random copolymer, poly(p-dioxanone-co-butylene-co-succinate) (PPBS), is tracked at different crystallization temperatures by optical microscopy. The crystal morphology is regulated by controlling the molecular structure of PPBS as well as the crystallization temperatures, that is, from rounded spherulite for the homopolymer counterpart to dendrites for the copolymer with high p-dioxanone (PDO) content and crystallization temperature. Different from previous works on dendritic crystals, interestingly, film thickness shows no obvious effect on the formation of dendrites. While we find that the crystal growth rate is seriously frustrated by the random structures of PPBS copolyester. Besides, small-angle X-ray scattering (SAXS) analysis indicated that the inter-lamellar region of PPBS copolyester is highly affected by the crystallization temperature. The PDO content, random structure, and high crystallization temperature were believed to be the main factors for the crystals transition from well-rounded spherulite to dendritic crystals.

The glass transition is a genuine imprint of temperature‐dependent structural relaxation dynamics of backbone chains in amorphous polymers, which can also reflect features of chemical transformations induced in macromolecular architectures. Optimization of thermophysical properties of polymer nanocomposites beyond the state of the art is contingent on strong interfacial bonding between nanofiller particles and host polymer matrix chains that accordingly modifies glass transition characteristics. Contemporary polymer nanocomposite configurations have demonstrated only marginal glass transition temperature shifts utilizing conventional polymer matrix and functionalized nanofiller combinations. We present nanofiller‐contiguous polymer network with aromatic thermosetting copolyester nanocomposites in which carbon nanofillers covalently conjugate with cure advancing crosslinked backbone chains through functional end‐groups of constituent precursor oligomers upon an in situ polymerization reaction. Via thoroughly transformed backbone chain configuration, the polymer nanocomposites demonstrate unprecedented glass transition peak broadening by about 100 °C along with significant temperature upshift of around 80 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2018, 56, 1595–1603

In terms of risk assessment especially for known and unknown substances migrating from food contact materials, quantification without corresponding reference substances currently poses a challenge. In the present study, the opportunity of a universal response quantification approach was evaluated by using a corona charged aerosol detector (CAD) for liquid chromatography combined with inverse gradient compensation. Characteristics of CAD detection in dependence of substance properties were analyzed with 46 randomly chosen reference substances. An almost equal CAD response (±20%) was achieved for non-volatile substances with a molecular weight of minimum 400 g/mol and a vapor pressure of maximum 10−8 Torr. We empirically defined an analytical parameter, Q50/35, the quotient of CAD peak areas at CAD evaporator temperatures of 50 °C and 35 °C, to predict the adequacy of the CAD universal response approach for quantification of known and unknown analyte substances. Exemplarily, we applied the CAD universal quantification approach for the determination of extractable oligomers below 1000 g/mol from a variety of food contact polycondensate plastic materials (e.g. polyesters like polyethylene terephthalate, polybutylene terephthalate, Tritan copolyester, polyamides 6, 6.6 and 6 T/6I and polyarylsulfones polyphenylsulfone and polyethersulfone). Quantitative results for in total 44 oligomers out of 11 materials were compared with established material-specific quantification methods using extracted oligomer mixtures as well as individual oligomers isolated from the mixtures. CAD-based quantification results were generally in accordance to published quantification approaches for polyamide oligomers and oligomers from polyarylsulfones. For oligomers extracted and isolated from polyester materials a slight underestimation was determined by CAD universal response approach. In terms of detection limits and accuracy, the universal CAD approach exhibits no advantages compared to established UV-methods, to date.

At present, developing a flame-retardant unit to solve the flammability and melt-dripping of poly(ethylene terephthalate) (PET) still is a key issue. To endow PET with good flame retardancy and low smoke releasing, a third monomer, N, N′-bis(2-hydroxyethyl)-biphenyl-3,4,3′,4′-tetracarboxylic diimide (BPDI) containing biphenyl biimide and without any traditional flame-retardant elements, is synthesized and incorporated to the main chain of PET to obtain the P(ET-co-BP)n copolyester via melt polymerization. The thermal stability, combustion and pyrolysis behaviors of the obtained copolyesters have been well investigated. Thermogravimetric analysis (TGA) results demonstrate that introducing BPDI into PET obviously improves its thermal stability and the forming ability of char residue. LOI, vertical UL-94 and cone calorimeter measurements have been applied to investigate the combustion behaviors of P(ET-co-BP)n. The results prove that P(ET-co-BP)n copolyesters containing biphenyl biimide show better fire safety, reflected by lower fire growth rate (FIGRA) and low smoke production. SEM and Raman results suggest that the char layers of P(ET-co-BP)n become denser and mainly consist of polyaromatic species with small and uniform microstructures. The pyrolysis behaviors of the copolyesters are investigated by Py-GC/MS, and the results showed that the biphenyl biimide structure units can lead to rearrangement reactions at high temperature, ultimately forming the phenanthrene ring structures during combustion. Without traditional flame-retardant elements like halogen and phosphorus, this novel PET copolyester is environmentally friendly and more safety.

To improve the flame retardant efficiency of aromatic Schiff base (BA), and adjust the crosslinking temperature of imine groups, a cyano group, an electron-drawing group has been introduced into the chemical structure of aromatic Schiff base to obtain a third monomer for poly(ethylene terephthalate) (PET), named as dimethyl-5-[(2-cyanobenzylidene)amino]-isophthalate (CBAA). Thermogravimetry-differential scanning calorimetry (TG-DSC) and dynamic rheological results prove that the PET-based copolyester containing CBAA (CBAAnPETs) can cross-link at higher temperature than that containing BA, which will not affect the preparing and processing of PET. DSC and wide angle x-ray diffraction (WAXD) results demonstrate CBAAnPETs remain good crystallization ability. Owing to the two types of cross-linking reactions, i. e. the reactions between Schiff base ( CH N-) and cyano group (-C≡N), and among -CH N- units, CBAA plays an important role in solid phase as well as gaseous phase endowing CBAAnPETs with excellent flame retardancy. With a low CBAA content (only 6.7 mol%), the copolyesters self-extinguish in 5 s with no melt drips in UL-94 vertical test, and its LOI value also increases to 31.0%. The peak heat release rate and total smoke release of the copolyesters obtained from cone calorimetry also observably decrease.

Objective: To evaluate light transmittance, surface roughness, and flexural modulus of copolyester retainer material after long-term exposure to different cleaning methods. Materials and Methods: Standardized copolyester retainer specimens (ACE) were subjected to seven chemical cleaning solutions for 6 months: Invisalign cleaning crystals, Retainer Brite, Polident, Listerine mouthwash, 2.5% acetic acid, 0.6% NaClO, and 3% H2O2. Seventy specimens (n = 10 per method, 50.8 mm × 12.7 mm × 1.0 mm) were exposed to the different solutions twice a week for 2 minutes or according to manufacturer's instructions and stored in artificial saliva at 37°C. Another group of specimens (n = 10) was brushed with a standardized toothbrushing machine for 2 minutes twice a week. At baseline and 6 months, light transmittance, surface roughness and flexural modulus of the specimens were quantified using spectrophotometry, profilometry, and three-point bend testing, respectively. Qualitative assessment was performed using scanning electron microscopy (SEM). Statistical analyses were accomplished at a significance level of .05. Results: The results indicated that light transmittance through the specimens decreased significantly from baseline for all cleaning methods at 6 months. Flexural modulus of the specimens decreased significantly for all cleaning methods except Invisalign crystals and Retainer Brite (P > .05). The Listerine group demonstrated the worst light transmittance change while H2O2 demonstrated the greatest change in flexural modulus of the specimens compared with other cleaning methods; however, no qualitative difference was observed using SEM analysis. Conclusions: The results suggest that different cleaning methods affect long-term physical properties of the ACE retainer material. At the present time, none of these cleaning methods is ideal for copolyester retainer material.

Two series of biobased even-odd aliphatic copolyesters, poly(butylene glutarate-co-butylene azelate) (PBGA) and poly(octylene glutarate-co-octylene azelate) (POGA), were prepared from even diol of 1,4-butanediol or 1,8-octanediol with odd diacids of glutaric acid and azelaic acid, respectively. These even-odd copolyesters can cocrystallize within the entire composition range despite being random, displaying a pseudo-eutectic point when their melting points are plotted as a function of composition. DSC and WAXD studies confirmed the isodimorphic behavior for PBGA and POGA. Then, the competition and miscibility in isodimorphism between PBGA and POGA were comparatively investigated. It demonstrated that the chain length of comonomeric diols can exert a considerable influence on the isodimorphic behavior of copolyesters. The comonomeric diol with longer chain shows greater ability in bridging the gap of competition between comonomer units. This insight contributes to predicting the composition of crystal transition point for isodimorphic copolyesters based on the molecular structure. For miscibility, the mutual insertion of comonomer units in the copolyester containing longer comonomeric diol is easier than in the copolyester with shorter comonomeric diol. Furthermore, a close dependence between the mechanical properties with competition and miscibility in such even-odd copolyesters was observed and discussed. The composition dependence of yield stress presents a similar pseudo-eutectic behavior that matches those exhibited by Tm versus composition, and that of the elongation at break shows an opposite tendency. In conclusion, our work here not only clarifies the effect of chain length of comonomeric diols on competition and miscibility of isodimorphism in the even-odd copolyesters, but also provides guidance in the selection of comonomeric diol for preparation of aliphatic copolyesters with desirable performances.

Bacteria endogenously residing within the plant tissues have attracted significant attention for production of biopolyester, polyhydroxyalkanoates (PHAs). Bacillus cereus RCL 02 (MCC 3436), a leaf endophyte of oleaginous plant Ricinus communis L. accumulates 81% poly(3-hydroxybutyrate) [P(3HB)] of its cell dry biomass when grown in mineral salts (MS) medium. The copolymer production efficiency of B. cereus RCL 02 was evaluated in valeric acid supplemented MS medium under biphasic cultivation condition. The copolymer so produced has been compared with the P(3HB) isolated from RCL 02 in terms of thermal, mechanical and chemical properties. Valeric acid supplementation as co-substrate in the medium has led to the production of copolymer of 3-hydroxybutyrate (3HB) and 3-hydroxyvalerate (3HV) [P(3HB-co-3HV)] with 14.6 mol% 3HV. The identity of the polymers has been confirmed by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopic studies. Thermogravimetric analysis (TGA) revealed that P(3HB) and P(3HB-co-3HV) films degraded at 278.66°C and 273.49°C, respectively. The P(3HB-co-3HV) showed lower melting temperature (165.03°C) compared to P (3HB) (170.74°C) according to differential scanning calorimetry (DSC). Incorporation of 3HV monomers decreased the tensile strength (21.52 MPa), tensile modulus (0.93 GPa), storage modulus (E′) (0.99 GPa) and increased % elongation at break (12.2%) of the copolyester. However, P(3HB) showed better barrier properties with lower water vapor transmission rate (WVTR) of 0.55 g-mil/100 in2/24 h. These findings emphasized exploration of endophytic bacterial strain (RCL 02) to produce biodegradable polyesters which might have significant potential for industrial application.