Search

With increased public awareness of fire-safety, flame retardant materials have been widely used and developed. Among them, a polyester called CPET, synthesized by the copolymerization of polyethylene terephthalate and 2-carboxyethyl (phenyl) phosphinic acid, has a good fire-safety and has been employed in the manufacture of synthetic fibers. However, the fabricated fiber made of CPET simultaneously possessing good flame retardancy and mechanical properties is a dilemma. Herein, we resolve this problem through the reactive blending of CPET with a type of thermotropic liquid crystal copolyester (PPDT) and subsequently solid-state polymerization (SSP). Thus, the fire-safety of the CPET/PPDTSSP blend improves greatly. The peak heat release rate, total heat release, and total smoke release decrease by 31.2%, 16.3%, and 11.0%, respectively, compared with those of CPET. Meanwhile, the CPET/PPDTSSP shows better crystallization and mechanical properties than CPET. The strength at yield and Young’s modulus of CPET/PPDTSSP increase by 20.0% and 15.8%, respectively. This blend shows great potential in the fabrication of fire-safety fibers with high strength.

The miscibility behavior of the blends of a copolyester of bisphenol-A with terephthalic and isophthalic acids in equal ratio and poly(methyl methacrylate) was studied by different experimental techniques. The intrinsic viscosities were determined for several copolyesters of bisphenol-A with terephthalic and isophthalic acids in equal ratio and poly(methyl methacrylate) blends in dilute chloroform solutions at 25°C by viscometric analysis. From experimental results of the intrinsic viscosities of the polymer blends, some miscibility parameters were obtained by applying the criteria proposed by some research groups. The miscibility of the blends was also studied using Fourier transform infrared spectroscopy and differential scanning calorimeter.

Aliphatic–aromatic copolyester/oxidized starch blends were formulated using different copolyester proportions and a constant starch–plasticizer ratio. After homogeneity evaluation, the samples were subjected to mechanical and thermal analyses. Subsequently, biodegradability evaluation under sandy loam garden soil was performed. The results showed that tensile strength, Young’s modulus and elongation at break presented a proportional increase with copolyester content. Differential scanning calorimetry analysis evidenced that the blend composition has no important influence on the glass transition temperature. The biodegradability tests showed a proportional relation between the amount of modified starch in the formulations and their degradation. Moreover, samples with a higher mass loss exhibited greater color changes, which indicate the microorganisms’ activity.

We present the first example of surface-initiated polymerization mediated by Lewis pairs for the synthesis of polymer brushes on planar substrates. The method enables the rapid grafting polymerization from the self-assembled monolayer or surface-attached macroinitiators, furnishing linear polymer brushes and bottle-brush brushes. Both homopolyester and block copolyester brushes can be synthesized via this versatile approach. This work not only opens up new opportunities for the application of Lewis pair-mediated polymerization but also enriches the surface-initiated polymerization on different surfaces.

A multiple amides-based linear organic compound (TMC-300) was synthesized and as an efficient nucleator was incorporated into PHBH to fabricate PHBH/TMC-300 composite to investigate effect of TMC-3...

The synthesis and modification of high performance thermotropic liquid crystal polyesters (TLCP) are still being investigated due to their excellent properties. In this study modification o...

In this study, the homopolymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and its copolymerizations with e‐caprolactone (CL) were carried out in detail using the isothiourea‐based Lewis pairs comprised 2,3,6,7‐tetrahydro‐5H‐thiazolo(3,2‐a)pyrimidine and magnesium halides (MgX₂) with benzyl alcohol (BnOH) as the initiator. The copolymerization of DTC and CL via one‐pot addition produced randomly sequenced copolymers. On the other hand, a well‐defined linear poly(e‐caprolactone)–block–poly(2,2‐dimethyltrimethylene carbonate) (PCL‐b‐PDTC) diblock copolymer was prepared by simple sequential ring‐opening polymerization of CL and DTC. In addition, poly(ω‐pentadecalactone)–block–PDTC diblock copolymer was successfully prepared by the same strategy. Moreover, PDTC–poly(ethylene glycol) (PEG)–PDTC triblock copolymer was synthesized in the presence of PEG 2000. The effects of different polymerization conditions on the polymerization reactions have been systematically discussed. The resulting polymers were characterized by the ¹H and ¹³C NMR spectra, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐ToF MS). The block copolyester structures were confirmed by the ¹³C NMR spectroscopy and DSC characterizations. These results indicated that the supposed mechanism was a dual catalytic mechanism. The proposed mechanism involved activation of the monomer via coordination to the MgX₂, and the initiator alcohol was deprotonated by base. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2349–2355

A partially bio-based bisphenol containing pendant azido group viz., 4,4′-(5-azidopentane-2,2-diyl) diphenol (AZBPA) was synthesized starting from 4,4′-bis (4-hydroxyphenyl) pentanoic acid. AZBPA was reacted with isophthaloyl chloride (IPC), terephthaloyl chloride (TPC) and a mixture of IPC/TPC (50:50 mol%) by phase transfer-catalyzed interfacial polycondensation route to obtain aromatic polyesters containing pendant azido groups. Copolyesters containing pendant azido groups were also synthesized by polycondensation of different molar proportions of AZBPA and commercially available 4,4′-(1-phenylethane-1,1-diyl) diphenol (BPA-AP) with IPC. Inherent viscosities and number average molecular weights of (co)polyesters were in the range 0.85–1.64 dL/g and 58,900–190,400, respectively, indicating the formation of reasonably high molecular weight polymers. Tough, transparent, and flexible films could be cast from chloroform solutions of these polyesters. X-Ray diffraction analysis showed that (co)polyesters were amorphous in nature. (Co)polyesters were characterized using FT-IR, 1H NMR spectroscopy, XRD, TGA and DSC analysis. The chemical modification of a representative copolyester containing pendant azido groups was carried out quantitatively using copper-catalyzed azide-alkyne cycloaddition (CuAAC) with two alkynes viz., phenyl acetylene (PA) and ethynyl-4-nitrobenzene (ENB). Additionally, (co)polyesters containing pendant azido groups were thermally cross-linked (170 °C/12 h) leading to the formation of network structures based on azide to nitrene decomposition and subsequent reactions on polyester backbone. The selected cross-linked polyesters were characterized by stress-strain measurements. The cross-linked polymers exhibited higher tensile strength and Young’s modulus and lower % elongation at break compared to corresponding pristine polyesters containing pendant azido groups.

In this paper, the synthesis and properties of poly(1,4-cyclohexanedimethylene-co-isosorbide terephthalate) (PCIT) with isosorbide (IS) content ranging from 16 to 61 mol% relative to the total diols amount were investigated. Amorphous polymers were successfully synthesized without isosorbide ring hydration. Glass transition temperature (Tg) linearly increased of 1.1 °C for each molar percent of isosorbide included in the polyester, meanwhile melting temperature (Tm) linearly decreased of 2.1 °C for semi-crystalline samples (up to 25 mol% of isosorbide). Molar masses of semi-crystalline samples were easily increased using high temperature solid-state polymerization (SSP) and reduced viscosity (ηred) higher than 70 mL g−1 were obtained. Semi-crystalline samples exhibit outstanding impact resistance compared with commercial high performance copolyester, whereas amorphous copolyesters exhibit acceptable mechanical properties coupled with high thermal resistance. Results confirmed the promising association between isosorbide and 1,4-cyclohexanedimethanol to reach tunable thermal and mechanical properties, depending on the targeted applications.

Fully biobased copolyesters poly(isosorbide-co-butylene 2,5-furandicarboxylate) (PISBF) were synthesized from 2,5-dimethylfuran dicarboxylate (DMFD), isosorbide (IS) and 1,4-butanediol (BDO) via transesterification and polycondensation reactions. The resulting copolymers were characterized by 1H NMR, 13C NMR, GPC, intrinsic viscosity, DSC, TGA and tensile testing, respectively. The NMR characterizations had confirmed that BDO was successfully introduced into the poly(isosorbide 2,5-furandicarboxylate) (PIF) polyester chains. Over the IS experimental composition range 20–80 % in copolymer chains, PISBF copolymers had TD, 5% values higher than 370 °C and TDM higher than 405 °C, and Tg values within the range of 55 °C and 150 °C. Introduction of BDO units into PIF chains imparted the PISBF copolyester with better mechanical performance than PIF, thus PISBF copolyesters with IS content of 20–50% were strong and toughened copolymers with Young’s modulus about 1400 MPa, tensile strength at break higher than 53 MPa, and elongation at break higher than 46%.

A series of three random copolyesters comprising biscoumarin and chalcone units as prime monomers, spaced with aliphatic alkyl chains of varying methylene units and 4,4′-oxydibenzoate, was synthesized and characterised by FTIR, NMR, TGA, DSC and XRD. The antimicrobial activity of the copolyesters was studied using Agar disc diffusion and broth dilution assay. The inhibitory effects of copolyesters were higher for Gram positive than Gram negative bacteria. All the copolyesters exhibited appreciable antimicrobial activity. In particular, copolyester 4c, poly(biscoumarin-4,4′-oxydibenzoate-3-methoxychalcone) exhibited highest inhibition zone range of 19±0.39 mm for Bacillus subtilis, 20±0.51mm for Staphylococcus aureus and 20±0.22 mm for Staphylococcus epidermidis. Bacillus subtilis was more sensitive towards copolyester 4c exhibiting a minimum inhibitory concentration of 39.05 μg/mL. Chalcone coupled biscoumarin copolyester presented good antimicrobial activities comparable with those of standard antimicrobial agents, Chloramphenicol and Amphotericin-B. Thus the incorporation of biscoumarin and chalcone units in the polymer chain exhibit very good antimicrobial activity against gram positive bacterial and fungal strains.

The interaction of (L)-lactic acid with p-tert-butylthiacalix[4]arene containing ethoxycarbonyl fragments in the 1,3-alternate conformation was studied in tetraglyme. For the first time, the lactic acid oligomer was obtained by polycondensation with the macrocycle and characterized by 1H, 13C NMR, IR spectroscopy, MALDI mass spectrometry and gel permeation chromatography. Thermal stability of the obtained copolyester of lactic acid and thiacalix[4]arene was studied by TG/DSC analysis and the effect of the macrocyclic platform on its thermal properties was shown. Copolyester obtained was thermally more stable than oligolactic acid. Self-assembly of synthesized oligomer was studied by dynamic light scattering method. It was shown that monodisperse particles (PDI = 0.13) with the size of 208 ± 4 nm are formed in CH3CN solution at 2.5 × 10−5 M concentration.

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...

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.

[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).

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.

In this paper, we study for the first time the effect of hard confinement on the isodimorphic crystallization of random copolyesters. A series of poly(butylene succinate-ran-caprolactone) samples encompassing the entire composition range were successfully infiltrated into nanoporous alumina templates (anodic aluminum oxide (AAO)) with a fixed diameter of 100 nm. The samples were characterized using scanning electron microscopy (SEM), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and grazing-incidence wide-angle X-ray scattering (GIWAXS). FTIR proved that poly(butylene succinate) (PBS)-rich nanofibers showed interactions between the copolyester chains and the walls of the AAO templates; however, the poly(ε-caprolactone) (PCL)-rich nanofibers did not show any interaction with the AAO walls. All infiltrated samples experienced a very large decrease in crystallization temperature, as expected, since the level of confinement is large enough to suppress heterogeneous nucleation. In spite of this, all copolymers were able to crystallize, regardless of composition. Additionally, when Tc or Tm is plotted versus copolymer composition, a clear pseudoeutectic point is observed. These results indicate that the isodimorphic behavior of the copolyesters is maintained under hard confinement. Infiltrated PCL undergoes homogeneous nucleation (inside the nanopore volume) as expected by the lack of interaction with the AAO walls. On the other hand, PBS exhibited a surface nucleation mechanism triggered by the interactions with the AAO walls. In the case of random copolymers, all PCL-rich copolymers nucleated homogeneously. However, in the case of PBS-rich copolymers, the nucleation gradually changed from surface-induced nucleation for neat PBS to homogeneous nucleation as the PCL concentration in the copolymers increased and the interactions of PBS chains with the AAO walls are diluted. The confinement under 100 nm nanopores did not change the orientation of the PBS or PCL phase crystals, which kept their chain direction perpendicular to the pore axis, as demonstrated by GIWAXS., The authors acknowledge the support of the National Key R&D Program of China (2017YFE0117800) and the National Natural Science Foundation of China (21873109, 51820105005). The authors would also like to acknowledge financial support provided by the BIODEST project; this project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 778092. The UPV/EHU and ICTP-CSIC Institutions acknowledge financial support from the Spanish Ministry of Science, Innovation, and Universities (MAT2017-83014-C2-2-P and MAT2017-83014-C2-1-P). M.S. thankfully acknowledges her Ph.D. fellowship by POLYMAT Basque Center for Macromolecular Design and Engineering. The authors would like to thank Dr. Antxon Martinez de Ilarduya and Prof. Sebastian Muñoz for their help in the synthesis of copolyesters at UPC, Spain. J.M. gratefully acknowledges support from the Provincial Council of Gipuzkoa under the program Fellow Gipuzkoa and “Fomento San Sebastián” in the framework program “Retorno del Talento Local” Donostia up! 2016.

Fully biobased blends of thermoplastic starch and a poly(butylene cyclohexanedicarboxylate)-based random copolyester containing 25 % of adipic acid co-units (PBCEA) are prepared by melt blending and direct extrusion film casting. The obtained films are characterized from the physicochemical and mechanical point of view and their fragmentation under composting conditions is evaluated. The results demonstrate that the introduction of adipic acid co-units in the PBCE macromolecular chains permits to decrease the blending temperature, thus avoiding unwanted starch degradation reactions. Moreover, the presence of small amounts of citric acid as compatibilizer further improves the interfacial adhesion between the two components and promotes the formation of micro-porosities within the films. The synergistic combination of these factors leads to the development of materials showing an elastomeric behavior, i.e. no evident yield and elongation at break higher than 450 %, good moisture resistance and fast fragmentation in compost.

Based on the excellent flame retardant performance, environment-friendly and abundant surface functional groups, Carbon Dots (CDs) were adopted as copolymerizable flame retardants for Poly(ethylene terephthalate)(PET) for the first time. The CDs with gelatin as precursor (gCDs) were synthesized by one-step hydrothermal method and copolymerized with pure terephthalic acid (PTA) and ethylene glycol(EG) to prepare flame retardant copolyester (gCDs-PET) based on the hydroxyl and amine groups on the surface of gCDs by in situ polymerization. It is demonstrated that gCDs-PET had showed better smoke suppressant and higher flame retardancy than pristine PET. The limiting oxygen index (LOI) of gCDs-PET composites achieved to 29% with the addition of 2.0 wt% gCDs. What is more, cone calorimeter tests showed that the peak value of heat release rate(pk-HRR) greatly decreased 42.66% and the total smoke production (TSP) reduced 62.64%. Besides, the flame-retardant mechanism disclosed that gCDs catalyzes the thermal decomposition of PET to form a shielding carbon layer, which handicap the release of combustible materials to the outside and expand the as-formed char, so that interrupt the combustion reaction. Furthermore, mechanical properties and spinnability of gCDs-PET was evaluated. It was demonstrated that the addition of gCDs into PET could enhance the mechanical strength and gCDs-PET could be made to fibers with excellent spinnability.

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.

International audience; The aim of this study is to investigate the printability conditions of a copolyester based polymer that has not received yet much attention. This material presents several advantages over PLA and ABS including its food contact compliance and BPA (Bisphenol A) free formulation. The determination of optimal conditions to print copolyester with FDM process was done by quantifying the influence of printing temperature on thermal behavior and tensile properties including Young's modulus, yield stress, tensile strength, ultimate properties, and fracture toughness. Analysis of damage mechanisms through the observation of fracture surfaces of printed copolyester were also performed using SEM. The results indicate a strong relationship between thermal cycling, tensile properties and printing temperature. It is also shownthat the mechanical behavior of printed copolyester is significantly affected by the filament arrangement within the meso-structure. Particular fracture patterns are revealed, which suggest the simultaneous action of three main damage mechanisms triggered by the in homogeneous change in the filament morphology at the rupture point.

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

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.

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.

To explore the relationship between thermal properties of a polymer and the biological performance of the resulting nanoparticle, all other parameters, including the hydrophobicity, should be kept constant. For this purpose, a gradient and a block copolyester were tailor-made via the triazabicyclodecene catalyzed ring-opening copolymerization of δ-valerolactone (δVL) and δ-decalactone (δDL) to match the hydrophobicity of poly(e-caprolactone) (PeCL). The degree of crystallinity of the semicrystalline materials was significantly reduced due to the incorporation of amorphous PδDL segments, as confirmed by dynamic scanning calorimetry. Atomic force microscopy revealed short and randomly oriented crystals in the gradient copolymer but longer and parallel aligned crystals for the block copolymer and PeCL. The stiffness of nanoparticles (Dh ≈ 170 nm) prepared from the polyesters correlated to the bulk crystallinity. The set of nanoparticles with constant hydrophobicity and size will facilitate direct access to t...

In this study, the preparation and properties of poly(ethylene terephthalate-co-2-methyl-1,3-propanediol) copolyester (PEMT) were reported. The PEMT crystallization properties, optical properties, thermal properties, rheological properties, and other properties were characterized by nuclear magnetic resonance (1H NMR), differential scanning calorimetry, thermo gravimetric analysis, ultraviolet visible near-infrared (UV-VIS-NIR) spectroscopy, polarizing microscope crystal culture, X-ray diffraction (XRD), and rheometer. It was proved that the crystallization abilities and crystallization rate of PEMT copolyesters were significantly affected by the content of 2-methyl-1,3-propanediol (MPO) units; the copolyester becomes amorphous when the content of MPO units exceeded 20 mol%. According to the XRD data, the diffraction peaks of PEMT remained unchanged compared with those of poly(ethylene terephthalate). The transmittance of copolyesters displayed a tendency of increasing at first and then declining with the increase in MPO. In addition to the crystallization properties, the transmittance of copolyesters was also affected by the extent of yellowing. When the MPO addition was less than 20 mol%, PEMT can maintain good thermal decomposition performance and processability.

This paper focuses on the effects of cyclic water immersion and salt spray aging tests on the physical properties of aromatic thermosetting copolyester (ATSP) matrix. Neat and graphene nanoplatelet (GNP) incorporated nanocomposite ATSP foam morphologies are employed to have enhanced surface areas exposed to the surrounding aqueous media, via porous configurations, which deliberately aggravate the extent of the aging on the matrix. The ATSP foams are fabricated through a thermal condensation polymerization process. Upon exposures to the periodic aging conditions, ATSP demonstrates an adsorption-regulated mass uptake mechanism. Contact angle measurements reveal GNP-neutral and hydrophobic characteristics for the ATSP matrix. Microstructural imaging exhibits no substantial physical degeneration in the matrix caused by the accelerated aging conditions. Glass transition temperatures of both neat and nanofiller incorporated ATSP forms display only marginal decreases stemmed from small volumes in the matrix occupied through the hygroscopic swelling. Thermal degradation stability of the ATSP morphology is effectively preserved following the aging processes. Compressive mechanical strengths of the foams lie within the regime of their virgin (not exposed to the aging conditions) counterparts yet show slight reductions. The ATSP matrix demonstrates an outstanding aging resistance to the subjected environments which can potentially address high-performance requirements in cutting-edge industrial applications.

New potentially biobased copolyesters having the same ethylene skeletal structure as poly(ethylene glycol-co-1,4-cyclohexanedimethanol terephthalate) (PETG) were synthesized based on 1,2-propanediol (1,2-PD) or 2,3-butanediol (2,3-BD) with 1,4-cyclohexane dimethanol (CHDM). The compositions of each copolyester were confirmed using 1H-NMR spectroscopy, and the detailed structure was analyzed using 2D NMR spectroscopy. In order to observe the effect of the lateral methyl groups on the microstructure and randomness in the sequences of the copolymers, 13C-NMR spectroscopy analysis was performed. The thermal properties, mechanical properties, and crystallinity of the copolyesters were analyzed using differential scanning calorimetry, thermogravimetric analysis, universal testing machine, and wide-angle X-ray diffraction. Depending on the number of the lateral methyl groups and the contents of the ethylene diol units, the copolyesters displayed different densities, glass transition temperatures (Tg), degrees of randomness and mechanical properties; however, a notable difference was not observed in thermal stability or crystallinity.

Novel copolyester thermoplastics based on 4,4′-bibenzoate and 3,4′-bibenzoate moieties with ethylene glycol were synthesized via melt polycondensations. Crystallization behavior was modified by the additional incorporation of terephthalate or isophthalate units into the backbones. Copolyester compositions were verified by 1H NMR spectroscopy and molecular weights were assessed using inherent viscosity (ηinh). Thermogravimetric analysis (TGA) showed single-step weight losses in the range of 360–400 °C. Differential scanning calorimetry (DSC) was used to determine melting points and glass transition temperatures over a wide range of copolyester compositions. Observation of thermal data was used to identify amorphous windows in composition ranges containing 3,4′BB and 4,4′BB moieties. Dynamic mechanical analysis (DMA) provided information about thermal transitions and sub-T g relaxations. Mechanical data were obtained using tensile testing to expand structure-property- morphology relationships. Permeability analysis helped to understand how monomer symmetry affects oxygen diffusivity and solubility in selected amorphous film and biaxially oriented copolyester samples.

A long-chain branched copolyester (i.e. p-hydroxybenzoic acid (HBA)/2-hydroxy-6-naphthoic acid (HNA)/1,1,1-tris(4-hydroxyphenyl)ethane (THPE) copolyester) and its extrusion film with superior physical properties to commercial Ticona A950 and Vecstar CTZ have been manufactured by the design of appropriate prescriptions, T-Die extrusion, and thermal treatment of crystal transformation. In order to investigate the fabricating feasibility for flexible copper clad laminate (FCCL) of fourth/fifth generation long-term evolution (4G/5G LTE), we have also agglutinated lab-made copolyester extrusion film with the copper foil by hot compression. Experimental results manifest that lab-made copolyester extrusion film is a highly potential FCCL substrate of 4G/5G LTE because its thickness, dielectric constant (Dk), dielectric loss (Df), hygroscopicity, yellowness index (YI), antistatic capability, flammability, melting temperature (Tm), coefficient of thermal expansion (CTE), and peel strength to copper foil are 50 μm, 2.90, 0.00140, 0.04%, 2.7, 6.5 × 109 Ω/□, UL-94 V0, 305 °C, 24.8 ppm/°C, and 29.9 lb/in, respectively.

Through a two-stage transesterification/esterification and polycondensation method, three biobased poly(hexamethylene 2,5-furandicarboxylate-co-adipate) (PHFA) copolyesters with low contents of hexamethylene adipate (HA) units were synthesized in this research. The thermal properties, crystal structure, and tensile properties of PHFA copolyesters and poly(hexamethylene 2,5-furandicarboxylate) (PHF) homopolymer were extensively studied and compared with each other. All PHFA copolyesters still maintained good thermal stability. The glass transition temperatures, melting point temperatures, and equilibrium melting point temperatures of PHFA copolyesters gradually decreased with the increase of HA units. PHFA copolyesters displayed the same crystal structures as PHF. The elongation at break remarkably increased to 498.3 ± 12.0% for the PHFA copolyester containing 30 mol% of HA units (PHFA30) from 197.3 ± 12.2% for PHF; moreover, PHFA30 still showed a relatively high melting point temperature of 116.4 °C, similar to that of biodegradable poly(butylene succinate) (about 114 °C).

Divanillic acid, the dimer of vanillic acid, has been widely used as an aromatic building block of bio-based polymers. In this study, a series of homo- and copolyesters composed of a methylated dialkoxydivanillic acid monomer with an alkoxy side-chain length of 1 or 4 carbon units, cyclohexanedimethanol, and an alkanediol with a chain length of 6, 8, or 12 carbon units was synthesized. The polyesters obtained exhibited high weight-average molecular weights in the range of 4.4 × 104 to 20 × 104 g/mol and degradation temperatures higher than 380 °C. Thermo-pressed films were prepared from all the polyesters. Their glass transition temperature and elongation-at-break values could be tuned from −1 to 120 °C and 3% to 1500%, respectively, by changing the lengths of the alkoxy side chain and the alkanediol as well as the composition of the copolyester.

High molecular weight aliphatic-aromatic copolyesters were synthesized from Sebacic acid, terephthalic acid, 1, 4-butanediol and glycerol via two-step esterification and polycondensation. Copolyesters were characterized with intrinsic viscosity, gel permeation chromatography, X-ray diffraction, Fourier infrared spectroscopy, nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, rheological analysis, tensile and puncture testing. All the copolyesters had a weight-average molecular weight over 20,000 g/mol or intrinsic viscosity over 1.1 dL/g when the glycerol content was in the range from 0.04 to 0.1 mol. Particularly, in addition to a small reduction in the tensile strength and elongation at break, the molecular weight, crystallinity, and intrinsic viscosity of the polyester were increased when the glycerol content was 0.04 mol, and the puncture resistance reached its maximum, which would improve the performance of the copolyester film. Obviously, the addition of glycerol did not significantly affect the melting temperature, glass transition temperature and thermal stability of polyesters, which would make it possible to use copolyester as a base material for cold-resistant hydrogels. As a whole, the level of glycerol within 0.1 mol is sufficient to improve the properties of copolyesters, which is beneficial to promote the generalization of them for films and hydrogels.

Sustainable biobased terpolyester based on heterocyclic dimethyl furan-2,5-dicarboxylate and isosorbide in combination with ethylene glycol and 1,4-cyclohexanedimethylene (PEICF) were successfully synthesized by two-step melt polymerization method and characterized. A series of PEICF terpolyester exhibited excellent heat resistive properties, with glass transition temperatures of 81–119 °C, and high molecular weights (Mw = 50,800 g mol−1). When esterification was carried out at fixed a COOH:OH molar ratio of 1:2, 1,4-cyclohexanedimethanol (CHDM) showed increased reactivity compared to isosorbide (ISB) and ethylene glycol (EG) monomers. As a result, EG was most likely to be placed at the end of the oligomer chains, which accelerated the transesterification process and drastically increased chain growth via chain scission at the carbonyl carbon adjacent to the ethylene unit due to steric hindrance. The zero shear viscosities of the PEICF terpolyester were much higher than that of the copolyester and increased with increasing ISB content. This study proposed a method for improving the low reactivity of dimethyl furan-2,5-dicarboxylate, which shows suppressed furan ring flipping, with sterically hindered ISB by using highly reactive CHDM at atmospheric pressure. These results signify the importance of controlling the synthetic conditions, as they affect the composition of the polymer backbone due to the different reactivities, volatilities, and steric hindrances of the monomers.

Retro-Diels-Alder reaction (rDA) has been widely used as a common modification approach for expanding functional applications of polymers. Especially, it has become an effective method of current cross-linking chemistry. With the goal of designing a cross-linkable PET-based copolyester toward flame retardancy and anti-dripping during combustion, dimethyl 5-(1,3-dioxo-3a,4,7,7a-tetrahydro-1H-4,7-methanoisoindol-2(3H)-yl) isophthalate (DMTMI) was incorporated as the functional co-monomer into PET chains via random transesterification polycondensation. Thermogravimetry-differential scanning calorimetry (TG-DSC) and rheological studies demonstrated the existence of cross-linking behavior at high temperature. By controlling the co-monomer content, expected flame retardancy was obtained, as illustrated by the results from the limiting oxygen index (LOI) and cone calorimetry. Furthermore, LOI values increased firstly and then decreased with the content of DMTMI increased, which was related to the existence of rDA reaction, and further proposed that a competitive relationship between the release of inflammable cyclopentadiene during rDA reaction and cross-linking behavior occurred in combustion. The hypothesis was verified through pyrolysis-gas chromatograph-mass spectrometry (Py-GC-MS).

Copolyester thermoplastic elastomers (COPE) have interesting mechanical properties but low chemical resistance in aggressive environments. Developing a treatment that would increase their chemical resistance while preserving their convenient bulk characteristics would be an advance. Radiofrequency plasma treatments in sulfur hexafluoride were undertaken. Surface properties and corrosion resistance of untreated and treated samples were investigated. Surface chemical composition was altered, resulting in a loss of organic elements and the incorporation of fluorine. Surface morphology and topography were changed by the removal of species during the treatment. Treatment tends to increase hydrophobicity; for the longer treatment times, hydrophobicity tends to be retained even after aging under atmospheric conditions. Resistance to chlorine attack was substantially increased upon fluorination, while resistance to oxygen attack was improved in some cases. The improvement in the corrosion resistance, which suggests an increase in lifetime under practical conditions, depends on fluorine incorporation and its effect on the physical stability of the structure.

Novel poly(lactic acid)-based chain extended triblock copolymers have been successfully synthesized in melt. The new polymers are characterized by a triblock ABA architecture, where A, is poly(lactic acid) and B is an ad hoc synthesized random biobased aliphatic copolyester poly(propylene/neopentyl glycol succinate). PLLA homopolymer has been also prepared for the sake of comparison. The samples under study were deeply characterized from the molecular, thermal and structural point of view. Mechanical and barrier properties and compostability were also investigated, in order to assess the potentiality of these materials in food packaging applications. The results obtained show that copolymerization leads to better mechanical response and barrier properties with respect to poly(lactic) acid homopolymer. Moreover, the presence of the central B block in the main polymer chain facilitates the process of compostability.

High glass transition temperature (Tg) polyesters based on cycloaliphatic diols such as 1,4-cyclohexanedimethanol (CHDM) and 2,2,4,4-tetramethyl-1,3-cyclobutanediol (TMCD) have attracted significant interest as bisphenol-A replacement. Whereas most literature reports focus on synthetic approaches, the present study investigates in depth various structure-property relationships in CHDM- and TMCD-containing novel copolyesters. Significant enhancements in Tg and increases in fragility are observed with the incorporation of bulky CHDM and rigid TMCD as comonomers. Substantial increase in oxygen permeability is measured with the incorporation of CHDM from 14.3 for poly(ethylene terephthalate) to 52.6 cc-mil/100in2.day.atm (SPU) for poly(1,4-cyclohexyldimethylene terephthalate). When 35 mol% CHDM is replaced by TMCD as comonomer, the value further increases to 137.0 SPU. In the case of CHDM-containing polyesters, improvements in both sub-Tg molecular mobility (due to additional chair-to-boat transformations) and fractional free volume (FFV) result in an increase in oxygen diffusion. On the other hand, substituting 35 mol% CHDM with more rigid TMCD yields a suppressed β-relaxation. In particular, CHDM-based copolyesters follow a linear correlation between the strength of β-relaxation and diffusivity whereas the TMCD-based copolyester exhibits a significantly positive deviation from the correlation. Therefore, the much higher FFV in TMCD-containing polyester plays a more important role in determining oxygen transport through such polymer. Finally, we demonstrate that copolyesters based on CHDM and TMCD display significantly enhanced resistance to moisture-induced plasticization and the competing penetrant effect.

In this study, we present carbon nanoparticle incorporated high-performance aromatic thermosetting copolyester (ATSP) nanocomposite foams. The ATSP nanocomposite foams were fabricated through a facile solid-state mixing method wherein carboxylic acid and acetoxy-functional group oligomers were initially combined with chemically pristine carbon nanofillers separately, while in powder form. The mixtures were then subjected to a thermal condensation polymerization reaction in which the constituent oligomers formed the ester backbone of the ATSP matrix and advanced the molecular weight while acetic acid was emitted as the by-product, and generated a porous nanocomposite morphology. As compared to a neat ATSP foam, the nanocomposite foams exhibited a reduced coefficient of thermal expansion by 25% to 75 × 10 −6 °C −1 . Thermal stability temperature at 5% mass loss was increased by 30 °C exceeding 500 °C. Compressive mechanical strength was enhanced two-fold, reaching 16 MPa along with a nearly doubled fracture strain, which ultimately yielded improved material toughness.