High molecular weight poly(ethylene‐2,5‐furanoate); critical aspects in synthesis and mechanical property determination

Furan‐2,5‐dicarboxylic acid (FDCA) is a widely advocated renewable substitute for terephthalic acid (TA). Preparation of high molecular weight FDCA based polyesters by an industrially common combination of melt polymerization and subsequent solid state post condensation is described. Ultimately, poly(ethylene 2,5‐furanoate) (PEF) with absolute M_n = 83,000 g mol^?1 is obtained, determined by triple detection Size Exclusion Chromatography. The bulk polymer properties of FDCA based polyesters, necessary to evaluate their industrial potential were determined the Young's modulus of PEF is determined to be 2450 ± 220 MPa and the maximum stress 35 ± 8 MPa. The influence of crystallinity on the mechanical properties as function of temperature was determined by dynamic mechanical thermal analysis. A detailed differential scanning calorimetry study on the crystallization behavior of high molecular weight PEF allowed to calculate the equilibrium melting temperature (T_m⁰) of 239.3 and 239.7 °C for the first and second melting peak, respectively. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4191–4199     

Synthesis and characterization of poly(2,5‐furan dicarboxylate)s based on a variety of diols

Novel polyesters from renewable resources based on 2,5‐dicarboxylic acid and several diols were synthesized and characterized using different polycondensation techniques. The aliphatic diols were sufficiently volatile to allow the use of polytransesterifications, which gave high‐molecular weight semicrystalline materials with good thermal stability. In particular, the polyester based on ethylene glycol displayed properties comparable with those of its aromatic counterpart, poly(ethylene terephthalate), namely, the most important industrial polyester. The use of isosorbide gave rise to amorphous polymers with very stiff chains and hence a high glass transition temperature and an enhanced thermal stability. The interfacial polycondensation between the acid dichloride and hydroquinone produced a semicrystalline material with features similar to those of entirely aromatic polyesters, characterized essentially by the absence of melting and poor solubility, both associated with their remarkable chain rigidity. The replacement of hydroquinone with the corresponding benzylic diol was sufficient to provide a more tractable polyester. This study provided ample evidence in favor of the exploitation of furan monomers as renewable alternatives to fossil‐based aromatic homologs. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Synthesis of furan dimer‐based polyamides with a high melting point

Polyamide composed of furan dimer, which is prepared from biomass‐derived organic molecule 2‐furfural, is synthesized. The reaction of 2,2′‐furan dimer 5,5′‐dicarbonyl chloride with several 1,ω‐diamines was carried out with a solution or interfacial polycondensation leading to the corresponding polyamide. Measurement of the melting point was performed resulting to exhibit a higher temperature compared with the related polyamide bearing a single furan ring composed of furan‐2,5‐dicarboxylic acid (FDCA). Thermal analyses (TG–DTA) also indicated higher temperatures of decomposition than those of FDCA‐derived polyamide. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1516–1519     

Fluorene‐rich high performance polyesters: Synthesis and characterization of 9,9‐fluorenylidene and 2,7‐fluorenylene‐based polyesters with excellent optical property

Polyesters PEs containing high content of fluorene units in their backbones were synthesized from 9,9‐diarene‐substituted fluorene diols ( 1 ) and fluorene‐based diacid chlorides ( 2 ) by high temperature polycondensation at 185 °C in diphenyl ether. The molecular weights of the polyesters PE1‐PE5 were in a range of M_w 25,000–165,000. The polyesters displayed their high thermostability: the glass transition temperatures (T_g) by differential scanning calorimetry analysis ranged from 109 to 217 °C, while the 10% weight loss temperatures (T_d10) measured by thermogravimetric analysis were over 400 °C in nitrogen and 395 °C in air. The polyesters had good solubility in most common organic solvents such as chloroform and toluene and gave tough, transparent and flexible cast films. The transmittance of the films was over 80% in the wavelength range from 450 to 700 nm in any PEs . The PEs exhibited high refractive index values around 1.65, while they had very low degree of birefringence. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2549–2556, 2008     

Synthesis and characterization of chiral liquid‐crystalline polyesters containing sugar‐based diols via melt polymerization

Liquid‐crystalline (LC) polyesters based on hexanediol or butanediol, dimethyl 4,4′‐biphenyldicarboxylate, and a sugar‐based diol, isosorbide or isomanide, were prepared with conventional melt polymerization. ¹H NMR spectroscopy confirmed that 50 mol % of the charged sugar diol was successfully incorporated into various copolyesters. Modest molecular weights were obtained, although they were typically lower than those of polyester analogues that did not contain sugar‐based diols. Thermogravimetric analysis demonstrated that the incorporation of isosorbide or isomanide units did not reduce the thermal stability in a nitrogen atmosphere. Melting points that ranged from 190 to 270 °C were achieved as a function of the copolyester composition. The lined focal conic fan textures, typical indications of a chiral smectic C LC phase, were observed upon the shearing of the LC melt under polarized light microscopy. Atomic force microscopy revealed that the twisted molecular orientation in the chiral LC phase induced periodically soft lamellar structures. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2512–2520, 2003     

Synthesis and characterization of novel renewable polyesters based on 2,5‐furandicarboxylic acid and 2,3‐butanediol

Novel polyesters from 2,5‐furandicarboxylic acid or 2,5‐dimethyl‐furandicarboxylate and 2,3‐butanediol have been synthesized via bulk polycondensation catalyzed by titanium (IV) n‐butoxide, tin (IV) ethylhexanoate, or zirconium (IV) butoxide. The polymers were analyzed by size exclusion chromatography, nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy (FTIR), matrix‐assisted laser ionization‐desorption time‐of‐flight mass spectrometry, electrospray ionization time‐of‐flight mass spectrometry, electrospray ionization quadruple time‐of‐flight mass spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. Fully bio‐based polyesters with number average molecular weights ranging from 2 to 7 kg/mol were obtained which can be suitable for coating applications. The analysis of their thermal properties proved that these polyesters are thermally stable up to 270–300 °C, whereas their glass transition temperature (T_g) values were found between 70 and 110 °C. Furthermore, a material was prepared with a molecular weight of 13 kg/mol, with a T_g of 113 °C. This high T_g would make this material possibly suitable for hot‐fill applications. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Polycondensation of Sebacic Acid with Primary and Secondary Hydroxyl Groups Containing Diols Catalyzed by Candida antarctica Lipase B

Abstract

The aliphatic polyesters are normally synthesized by ester interchange reactions or direct esterification of hydroxyacids or diacid/diol combinations. Biotransformation, utilizing the enzymes as catalysts, was accepted as an alternative route for the synthesis of aliphatic polyesters and offers various advantages compared with the conventional, metal-catalyzed polymerization reactions. Previous studies indicated that lipase-catalyzed polycondensation reactions between diols and diacids occurred preferentially at primary hydroxyl groups of diols, when diols contained both primary and secondary hydroxyl groups. In this work, we investigated lipase-catalyzed polycondensation of diacids and secondary hydroxyl group–containing diols, and successfully synthesized polyesters by polycondensation with secondary hydroxyl groups as well as primary hydroxyl groups. Various diols, glycerol, 1,2-propanediol, 1,3-butanediol, 2,3-butanediol, and 2,4-pentanediol were tested for the polycondensation. The polymerization was achieved by heating a mixture of lipase B, sebacic acid, and the diols in anhydrous toluene at 100 °C for 72 h. The resulting polymers were characterized by ¹H and ¹³C NMR spectroscopy, Fourier transform–infrared spectroscopy, thermogravimetric analysis, and gel permeation chromatography.     

Partially bio‐based aromatic polyimides derived from 2,5‐furandicarboxylic acid with high thermal and mechanical properties

Two novel bio‐based diamines are synthesized through introduction of renewable 2,5‐furandicarboxylic acid (2,5‐FDCA), and the corresponding aromatic polyimides (PIs) are then prepared by these diamines with commercially available aromatic dianhydrides via two‐step polycondensation. The partially bio‐based PIs possess high glass transition temperatures (T_gs) in the range from 266 to 364 °C, high thermal stability of 5% weight loss temperatures (T_5%s) over 420 °C in nitrogen and outstanding mechanical properties with tensile strengths of 79–138 MPa, tensile moduli of 2.5–5.4 GPa, and elongations at break of 3.0–12.3%. Some colorless PI films (PI‐1‐b and PI‐1‐c) with the transmittances at 450 nm over 85% are prepared. The overall properties of 2,5‐FDCA‐based PIs are comparable with petroleum‐based PI derived from isophthalic acid, displaying the potential for development of innovative bio‐based materials. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 1058–1066     

Aza‐Michael addition reaction: Post‐polymerization modification and preparation of PEI/PEG‐based polyester hydrogels from enzymatically synthesized reactive polymers

The utility of aza‐Michael addition chemistry for post‐polymerization functionalization of enzymatically prepared polyesters is established. For this, itaconate ester and oligoethylene glycol are selected as monomers. A Candida Antarctica lipase B catalyzed polycondensation reaction between the two monomers provides the polyesters, which carry an activated carbon‐carbon double bond in the polymer backbone. These electron deficient alkenes represent suitable aza‐Michael acceptors and can be engaged in a nucleophilic addition reaction with small molecular mono‐amines (aza‐Michael donors) to yield functionalized linear polyesters. Employing a poly‐amine as the aza‐Michael donor, on the other hand, results in the formation of hydrophilic polymer networks. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 745–749     

Thermal properties of poly(alkylene dicarboxylate)s derived from 1,12‐dodecanedioic acid and even aliphatic diols

A series of new aliphatic polyesters derived from 1,12‐dodecanedioic acid and different diols with an even number of methylene units have been studied to assess the effect of the chemical structure on the final thermal properties of the materials. The polyesters have high thermal stability and are fast crystallizing polymers, with crystallization rate similar to that of polyethylene (PE). This behavior is connected to the fact that long aliphatic chains assume conformational characteristics very similar to that of PE. However, the polyester prepared from ethanediol shows a peculiar behavior (for example, double melting peak, melting and crystallization temperatures, which do not fit the trend of those of the other samples and ringed spherulites) owing to a probable different conformation, deviating from the all‐trans planar typical of PE. In the isothermal crystallization studies, a bell‐shape trend has been found for the crystallization rate as a function of the number of ? (CH₂)? units in the diol. The high crystallization rate of the sample with long ? (CH₂)? sequences has been attributed to the high chain flexibility and, thus, high mobility in the molten state and ease of chain folding. By reducing the aliphatic sequence length, instead, implications of the structural characteristics of the samples are probably involved. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1053–1067, 2007     

Polyamide–polyester multiblock copolymers by chain‐coupling reactions of carboxy‐terminated polymers with phenylene and pyridylene bisoxazolines

Polyamide–polyester multiblock copolymers were synthesized through the reaction of α,ω‐dicarboxy polyamides and polyesters with various arylene bis(2‐oxazoline)s. 2,2′‐(2,6‐Pyridylene)bis(2‐oxazoline) was very reactive and yielded multiblock copolymers with number‐average molar masses ranging from 15,000 to 25,000 after 30 min of reaction in the bulk at 200 °C. The molar masses and thermal properties of the resulting random multiblock copolymers (glass‐transition temperature, melting temperature, and melting enthalpy) were close to those of their alternating homologues prepared by conventional polycondensation between diamino polyamides and dicarboxy polyesters. This showed that the presence of coupling agent moieties in the polymer chains did not exert a significant influence on the block copolymer morphology. The chain‐coupling method showed several advantages over conventional polycondensation: a much shorter reaction time, a lower temperature, no byproducts, and easy control of the final copolymer properties through the mass ratio of the starting oligomers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1331–1341, 2005     

A series of furan‐aromatic polyesters synthesized via direct esterification method based on renewable resources

A series of furan‐aromatic polyesters were successfully synthesized via direct esterification method starting from 2,5‐furandicarboxylic acid, ethylene glycol, 1,3‐propanediol, 1,4‐butanediol, 1,6‐hexanediol, and 1,8‐octanediol and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹H NMR), X‐ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), tensile tests, and so on. The preliminary evidence clearly showed that direct esterification method was rewarding and worthy to synthesize these furan‐aromatic polyesters. The densities of furan‐aromatic polyesters were ranging from 1.19 to 1.38 kg/m³. The FTIR and ¹H NMR confirmed their expected structures in detail. The results of XRD showed that these furan‐aromatic polyesters were crystalline polyesters. The results of DSC, TGA, DMA, and tensile tests showed that they behaved as thermoplastic polyester, had satisfactory thermal and mechanical properties, and their thermal stabilities were quite similar to that of corresponding benzene‐aromatic polyesters. The results of contact angle measurement showed that they were hydrophilic. The properties above showed that furan‐aromatic polyesters based on renewable resources could be a viable alternative to their successful petrochemical benzene‐aromatic counterpart. Furthermore, they could be used as biopolymer materials according their satisfactory thermal and mechanical properties and hydrophilicity in the future. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis,thermal, rheological characteristics,and enzymatic degradation of aliphatic polyesters with lignin‐based aromatic pendant groups

This research aims to produce lignin‐based biodegradable polyesters with improved thermal quality. A series of aliphatic polyesters with lignin‐based aromatic side groups were synthesized by conventional melt‐polycondensation. Decent molecular weight (21–64 kg mol^?1) was achieved for the polymerizations. The molecular structures and thermal and mechanical properties of the obtained polyesters were characterized. As a result, the obtained polyesters are all amorphous, and their glass‐transition temperature (T_g) depends on the size of the pendant aromatic group (31–51 °C). Furthermore, according to the TGA results, the thermal decomposition temperatures of the polyesters are all above 390 °C, which make them superior compared with commercial biodegradable polyesters like polylactic acid or polyhydroxyalkanoates. Finally, rheological characteristics and enzymatic degradation of the obtained polyesters were also measured. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2314–2323     

Thermotropic liquid‐crystalline polyesters containing biphenyl mesogens in the main chain: The effect of connectivity

A homologous series of main‐chain thermotropic liquid‐crystalline polyesters containing rigid biphenyl mesogen and flexible methylene spacers were synthesized with the AB‐type self‐polycondensation approach. The polyesters were characterized with ¹H NMR, gel permeation chromatography, thermogravimetric analysis, differential scanning calorimetry, polarized light optical microscopy, and X‐ray diffraction. These polyesters, containing trimethylene spacers on the acid side and various spacers on the alcohol side of the biphenyl mesogen, showed an odd–even effect in the transition temperatures and mesophase type. The even members showed higher transition temperatures than the odd ones. A normal smectic mesophase was observed for the even members, whereas the odd‐membered counterparts exhibited a tilted smectic mesophase. To study the effect of connectivity, the mesophase characteristics of these polyesters were compared with those of the isomeric AB‐type polyesters without any methylene spacer on the acid side of the biphenyl moiety. The mesophase characteristics were insensitive to whether the mesogen was connected to a carboxyl unit or a methylene unit. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2734–2746, 2004     

Synthesis,characterization, and in vitro degradation of liquid‐crystalline terpolyesters of 4‐hydroxyphenylacetic acid/3‐(4‐hydroxyphenyl)propionic acid with terephthalic acid and 2,6‐naphthalene diol

Melt‐processable liquid‐crystalline terpolyesters of 4‐hydroxyphenylacetic acid (HPAA) and 3‐(4‐hydroxyphenyl)propionic acid (HPPA) with terephthalic acid and 2,6‐naphthalene diol were synthesized by one‐step acidolysis melt polycondensation followed by postpolymerization and were characterized with viscosity studies, Fourier transform infrared (FTIR) and NMR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized light microscopy, and wide‐angle X‐ray diffraction. The melting behaviors and liquid‐crystalline transition temperatures of the terpolyesters were dependent on the composition of the HPAA/HPPA content. The transition temperatures of the polyesters could be effectively reduced by the introduction of an even number of built‐in short methylene spacers in combination with the 2,6‐naphthalene offset structure. A terpolyester with an HPPA content of 33% (NTP33) showed optimum properties for the glass‐transition temperature, around 71 °C, and the melting temperature, near 240 °C, with a Schlieren nematic texture. The polymer showed excellent flow behavior in a Brabender plasticorder. It was also thermally stable up to 400 °C. NTP33 showed 2.5% in vitro hydrolytic degradation in buffer solutions of pH 10 at 60 °C after 540 h. Considerable enzymatic degradation was also observed with porcine pancreas lipase/buffer solutions in comparison with Candida rugosa lipase after 60 days. The degradation was also followed with FTIR, DSC, and TGA. Apart from the temperature and pH of the buffer solution, several structural parameters, such as the aromatic content, crystallinity percentage, and composition of the polymer, affected the degradation behavior. FTIR studies indicated the involvement of chain scission during degradation. Scanning electron microscopy studies further showed that surface erosion also played a major role in the degradation. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 1845–1857, 2002     

Biodegradable network elastomeric polyesters from multifunctional aromatic carboxylic acids and poly(ϵ‐caprolactone) diols

Novel biodegradable network polyesters were prepared from multifunctional aromatic carboxylic acids [trimesic acid (Y), pyromellic acid (X), and mellic acid (Y_M)] and poly(?‐caprolactone) (PCL) diols with molecular weights of 530, 1250, and 2000. Prepolymers prepared by a melt polycondensation method were cast from dimethylformamide solutions and postpolymerized at 220 °C for various times to form a network. The resultant films were transparent, flexible, and insoluble in organic solvents. The network polyesters obtained were characterized by infrared absorption spectra, wide‐angle X‐ray diffraction analysis, density measurements, differential scanning calorimetry, thermomechanical analysis, and tensile testing. Some network polyester films, including YPCL_1250, XPCL₁₂₅₀, and Y_MPCL₂₀₀₀, showed elastomeric properties with high ultimate elongation and low tensile modulus. The enzymatic degradation was measured by the weight loss of the network polyester films in a buffer solution with Rhizopus delemar lipase at 37 °C. The degree and rate of degradation increased with the increasing molecular weight of the PCL diols, but they decreased in the order of YPCL > XPCL > Y_MPCL because of the increase in the crosslinking densities of the network films. The degraded products after enzymatic degradation showed that the ester linkage of the PCL component and the aromatic ester linkage between Y and PCL diols were hydrolyzed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4523–4529, 2002     

Synthesis and characterization of hyperbranched polyesters from glycerol‐based AB2 monomer

This article describes the synthesis of a new glycerol‐based AB₂ type monomer—ethyl{3‐[2‐hydroxy‐1‐(hydroxymethyl)ethoxy]propyl}thioacetate ( 4 ) and its application for the preparation of hyperbranched polyesters. The polycondensation of 4 has been performed over a wide range of catalysts and reaction conditions leading to polymers containing solely primary hydroxyl groups. The polycondensation progress has been monitored by means of ¹H NMR. The degree of branching of the polymers showed to be in the range of 0.5 ± 0.03. The obtained polyesters easily undergo hydrolysis or alcoholysis and may be of interest as recycled materials. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 3860–3868, 2009     

Combining “click” chemistry and step‐growth polymerization for the generation of highly functionalized polyesters

Aliphatic polyesters bearing pendant alkyne groups were successfully prepared by step‐growth polymerization of different building blocks such as adipic acid and succinic acid in combination with an acetylene‐based diol, 2‐methyl‐2‐propargyl‐1,3‐propanediol, besides 1,4‐butanediol and ethylene glycol. It was demonstrated that the alkyne groups survive the high reaction temperatures (200 °C) in the presence of a radical inhibitor. The alkyne loading has been tuned by the ratio of the different monomers used, up to 25 mol % of alkyne groups. Subsequently, the alkyne groups have been reacted with azides by the copper‐catalyzed Huisgen 1,3‐dipolar cycloaddition reaction, a popular type of “click” chemistry. “Click” reactions have been performed quantitatively in the presence of benzyl azide and azide‐terminated poly(ethylene glycol), yielding brush copolymers in the latter case. Kinetic investigations about this click reaction have been performed by means of on‐line Fourier transform mid‐infrared spectroscopy, which was reported for the first time in the field of the click chemistry research. A whole range of functionalized polyesters, based on poly(ethylene succinate) and poly(butylene adipate), is available, the properties of which can be tailored by choosing the appropriate azide compound. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6552–6564, 2008     

Synthesis and kinetic modeling of biomass‐derived renewable polyesters

The biomass‐derived polyesters poly(1,3‐propylene 2,5‐furandicarboxylate) (PPF), poly(1,3‐propylene succinate) (PPS) and poly(1,3‐propylene 2,5‐furandicarboxylate‐co‐1,3‐propylene succinate) (PPFPS) have been synthesized via a two‐step process involving polycondensation and azeotropic distillation. The kinetic parameters were obtained by fitting the experimental data from a batch polymerization reactor to three different kinetic models for polyesterification reactions. The activation energies of the all monomer systems were obtained by Arrhenius plots. Given the increasing availability of biomass‐derived monomers their use in renewable polyesters as substitutes for fossil fuel derived chemicals becomes a distinct possibility. The kinetic modeling of the uncatalyzed polyesterification reactions will enable further integrative process simulation of the studied bioderived polymers and provide a reference for future practical study or industrial applications of catalyzed polyesterification reactions and other bioderived monomer systems. © 2016 The Authors. Journal of Polymer Science Part A: Polymer Chemistry Published by Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2876–2887     

Unsaturated,biobased polyesters and their cross‐linking via radical copolymerization

Biobased, unsaturated polyesters derived from isosorbide, maleic anhydride, and succinic acid were synthesized and characterized. The presence of maleic anhydride units in the structure of the polyesters allowed converting them into cured coatings by radical copolymerization with crosslinking agents such as 2‐hydroxyethyl methacrylate, N‐vinyl‐2‐pyrrolidinone, acrylic acid or methacrylamide. The investigated polyesters were obtained via bulk polycondensation, catalyzed by titanium(IV) n‐butoxide. 2D NMR and MALDI‐Tof‐MS spectroscopy proved that this polymerization resulted in isomerization of maleic acid units into fumaric ones and in the formation of slightly branched structures by the reaction of isosorbide (end) groups with main chain unsaturated bonds. Moreover, some double bonds proved to have reacted with the condensation by‐product water. The resulting polyesters displayed the expected correlation between variables such as molecular weight and content of unsaturated bonds and their T_g values. Since the thermal properties of the obtained polyesters were appropriate for coating applications, the polymers were crosslinked with unsaturated monomers by radical copolymerization. The crosslinking process was studied using FTIR spectroscopy and by measurements of the soluble part of the cured coatings. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2885–2895, 2010