High Molecular Weight Polyesters Research Articles

Molecular Characterization of High Molecular Weight Polyesters by Matrix-Assisted Laser Desorption/Ionization High-Resolution Time-of-Flight Mass Spectrometry Combined with On-plate Alkaline Degradation and Mass Defect Analysis

Matrix-assisted laser desorption ionization high-resolution time-of-flight mass spectrometry (MALDI HR TOF MS) is a powerful tool for the molecular characterization of industrial polymers. However, accurate mass determination and resolution of isobaric ions are possible for oligomer samples only typically below m/z 3000. To cut long polymer chains into oligomers suitable for high-resolution mass spectrometry, we propose a simple “on-plate” alkaline degradation of polyesters as a sample pretreatment technique prior to the MALDI TOF MS measurement. This pretreatment can be performed on a MALDI target using a small amount of sample (μg or less) and 1 μL of alkaline reagent by simple pipetting. Informative mass spectra in the oligomeric mass range are successfully recorded but complicated by the variation of end-groups and the copolymeric composition of the degradation products. Data processing is assisted by a series of advanced Kendrick mass defect (KMD) analyses recently proposed by the authors to plot visually understandable two-dimensional maps. On-plate degradation pretreatment, high-resolution MALDI TOF MS measurements, and advanced KMD analyses are innovatively combined for the compositional characterization of bacterial poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid) and industrial poly(ethylene terephthalate) samples.Graphical ᅟ

Synthesis of high molecular weight aromatic polyesters via integrated alternating ring-opening copolymerization and chain extension methods

Due to their good mechanical properties, high molecular weight polyesters (PEs) are highly desirable for a wide range of applications especially in the packaging industry. However, the synthesis of high molecular weight polymers by energy efficient methods is difficult. In this study, a series of semi-aromatic PEs were synthesized via the alternating ring-opening copolymerization (ROCOP) of phthalic anhydride (PA) and cyclohexene oxide (CHO) using a salen chromium(III) complex as a catalyst and 4-(dimethylamino)pyridine as a cocatalyst. By varying the molar ratios between CHO and PA, PEs of different molecular weights were obtained. Hexamethylene diisocyanate was used as a chain extender that further increased the molecular weights of these PEs. These chain extended aromatic polyesters (PE-Xs) showed significant improvement in the glass transition temperature (Tg) values. Thus, integration of ROCOP with the chain extension method can be used as an effective strategy to prepare high molecular weight PEs with improved thermal stabilities and enhanced mechanical properties. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47200.

Synthesis of High Molecular Weight Polyester Using in Situ Drying Method and Assessment of Water Vapor and Oxygen Barrier Properties.

The preparation of renewable polyesters with good barrier properties is highly desirable for the packaging industry. Herein we report the synthesis of high molecular weight polyesters via an innovative use of an in situ drying agent approach and the barrier properties of the films formed from these polyesters. High number average molecular weight (Mn) semiaromatic polyesters (PEs) were synthesized via alternating ring-opening copolymerization (ROCOP) of phthalic anhydride (PA) and cyclohexene oxide (CHO) using a salen chromium(III) complex in the presence of 4-(dimethylamino)pyridine (DMAP) cocatalyst. The use of a calcium hydride (drying agent) was found to enhance the number Mn of the synthesized PEs, which reached up to 31.2 ku. To test the barrier properties, PE films were prepared by solvent casting approach and their barrier properties were tested in comparison poly(lactic acid) films. The PE films showed significantly improved water vapor and oxygen barrier properties compared to the commercial poly(lactic acid) (PLA) film that suggests the potential use of these PEs in in the food packaging industry.

Efficient Physisorption of Candida Antarctica Lipase B on Polypropylene Beads and Application for Polyester Synthesis

In the present work, Candida antarctica lipase B (CaLB) was adsorbed onto polypropylene beads using different reaction conditions, in order to investigate their influence on the immobilization process and the enzyme activity of the preparations in polymerization reactions. In general, lower salt concentrations were more favorable for the binding of enzyme to the carrier. Polymerisation of dimethyl adipate (DMA) and 1,4-butanediol (BDO) was investigated in thin-film systems at 70 °C and at both atmosphere pressure (1000 mbar) and 70 mbar. Conversion rates and molecular masses of the reaction products were compared with reactions catalyzed by CaLB in its commercially available form, known as Novozym 435 (CaLB immobilized on macroporous acrylic resin). The best results according to molecular weight and monomer conversion after 24 h reaction time were obtained with CaLB immobilized in 0.1 M Na2HPO4\NaH2PO4 buffer at pH 8, producing polyesters with 4 kDa at conversion rates of 96% under low pressure conditions. The stability of this preparation was studied in a simulated continuous polymerization process at 70 °C, 70 mbar for 4 h reaction time. The data of this continuous polymerizations show that the preparation produces lower molecular weights at lower conversion rates, but is comparable to the commercial enzyme concerning stability for 10 cycles. However, after 24 h reaction time, using our optimum preparation, higher molecular weight polyesters (4 kDa versus 3.1 kDa) were obtained when compared to Novozym 435.

Solid-State Polymerization of Poly(Ethylene Furanoate) Biobased Polyester, II: An Efficient and Facile Method to Synthesize High Molecular Weight Polyester Appropriate for Food Packaging Applications.

The goal of this study was to synthesize, through a facile strategy, high molecular weight poly(ethylene furanoate) (PEF), which could be applicable in food packaging applications. The efficient method to generate PEF with high molecular weight consists of carrying out a first solid-state polycondensation under vacuum for 6 h reaction time at 205 °C for the resulting polymer from two-step melt polycondensation process, which is catalyzed by tetrabutyl titanate (TBT). A remelting step was thereafter applied for 15 min at 250 °C for the obtained polyester. Thus, the PEF sample was ground into powder, and was then crystallized for 6 h at 170 °C. This polyester is then submitted to a second solid-state polycondensation (SSP) carried out at different reaction times (1, 2, 3.5, and 5 h) and temperatures 190, 200, and 205 °C, under vacuum. Ultimately, a significant increase in intrinsic viscosity is observed with only 5 h reaction time at 205 °C during the second SSP being needed to obtain very high molecular weight PEF polymer greater than 1 dL/g, which sufficient for manufacturing purposes. Intrinsic viscosity (IV), carboxyl end-group content (–COOH), and thermal properties, via differential scanning calorimetry (DSC), were measured for all resultant polyesters. Thanks to the post-polymerization process, DSC results showed that the melting temperatures of the prepared PEF samples were steadily enhanced in an obvious way as a function of reaction time and temperature increase. It was revealed, as was expected for all SSP samples, that the intrinsic viscosity and the average molecular weight of PEF polyester increased with increasing SSP time and temperature, whereas the number of carboxyl end-group concentration was decreased. A simple kinetic model was also developed and used to predict the time evolution of polyesters IV, as well as the carboxyl and hydroxyl end-groups of PEF during the SSP.

High Molecular Weight Polyesters Derived from Biobased 1,5-Pentanediol and a Variety of Aliphatic Diacids: Synthesis, Characterization, and Thermo-Mechanical Properties

High molecular weight aliphatic polyesters were synthesized from biobased 1,5-pentanediol and aliphatic diacids with 4, 5, 6, 9, 10, or 12 carbon atoms via melt polycondensation. The poly(1,5-pentylene dicarboxylate)s were characterized with intrinsic viscosity, gel permeation chromatography (GPC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), thermogravimetric analysis (TGA), and tensile testing. The effects of dicarboxylate chain length on crystalline structure and thermo-mechanical properties were investigated. All the polyesters had weight-average molecular weight over 100,000 g/mol or intrinsic viscosity over 1.05 dL/g except poly(1,5-pentylene adipate) (PPeA), which was less thermally stable than others. As semicrystalline polymers, they have a polyethylene-like crystal structure and crystallize rapidly except poly(1,5-pentylene succinate) (PPeS). As a whole, the crystallizability and melting temperature (Tm) increase with dicarboxyla...

Synthesis and Properties of Biobased Multiblock Polyesters Containing Poly(2,5-furandimethylene succinate) and Poly(butylene succinate) Blocks

Novel biobased multiblock polyesters poly(2,5-furandimethylene succinate)-b-poly(butylene succinate) (PFS-PBS) containing PFS and PBS blocks were synthesized in a full composition range via chain-extension reaction of dihydroxyl terminated poly(2,5-furandimethylene succinate) (HO-PFS-OH) and poly(butylene succinate) (HO-PBS-OH) prepolymers. High molecular weight polyesters were obtained, and the stability of double bonds in 2,5-bis(hydroxymethyl)furan was guaranteed via this preparation procedure. The obtained copolyesters were characterized with 1H NMR, gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, polarized optical microscopy, wide-angle X-ray diffraction, and the mechanical properties were also investigated. No transesterfication reaction happened during chain-extension reaction, and the expected multiblock chemical structure was obtained. The PBS block is crystallizable, while the PFS block is nearly amorphous. Crystallization temperature and degree of crystallinity gradually decreased with increasing PFS fraction, but the melting temperature of crystalline samples showed no sharp reduction (109.4–105.2 °C). The crystallization rate also decreased with incorporation of PFS during isothermal crystallization, but the crystallization mechanism remained unchanged at any composition. Finally, the PFS-PBS copolyesters exhibit widely tunable mechanical properties, ranging from semicrystalline thermoplastics to amorphous soft elastomer-like polymers.

Thermally Degradable Polyesters with Tunable Degradation Temperatures via Postpolymerization Modification and Intramolecular Cyclization

We report the novel synthesis of thermally degradable polyesters through the postpolymerization modification of an unsaturated aliphatic polyester from maleic acid via Michael addition reaction with β-amino mercaptans. A high molecular weight polyester (P0) was synthesized by the acyclic diene metathesis (ADMET) polymerization of a diene monomer, di(10-undecenyl) maleate. Postpolymerization modification of P0 with three β-amino mercaptans (2-aminoethanethiol, l-cysteine methyl ester, and 2-(butylamino)ethanethiol) and 2-mercaptoethanol via the selective and quantitative thiol–Michael addition reaction with the maleate vinylic double bonds afforded four polyesters (P1–P4). All the polyesters were characterized by 1H NMR, GPC, and MALDI-TOF-MS, and their thermal properties were studied by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The three polymers with pendant amino groups (P1–P3) subjected to thermal-induced degradation in the solid state, the driving force of which i...

Enzymatic ring opening polymerization of ω-pentadecalactone using supercritical carbon dioxide

ω-pentadecalactone, a cyclic macrolactone can be polymerized by enzymatic ring opening polymerization (e-ROP). The resulting polyester, poly(ω-pentadecalactone) has mechanical and biocompatibility properties that make it desirable for biomedical uses, especially for bone and cartilage tissue regeneration. Conventional synthesis of poly(ω-pentadecalactone) involves acid or metal catalysts and organic solvents such as toluene that can leave toxic residuals in obtained material. In this work, e-ROP of ω-pentadecalactone was performed using supercritical carbon dioxide (scCO2) as solvent, a co-solvent and Novozym 435 lipase as catalyst. Different polymerization conditions were tested to obtain high molecular weight polyesters. Reactions conducted using only scCO2 as solvent showed yields around 60wt% and molecular weights up to 33,000g/mol. Higher molecular weights were obtained when a co-solvent was used. The results also showed a strong influence of water content on enzyme and monomer concentration in reaction medium over the final polymer molecular weight and reaction yield.

Enzymatic reactive extrusion: moving towards continuous enzyme-catalysed polyester polymerisation and processing

Enzyme catalysed ring-opening polymerisation was performed by reactive extrusion gave high molecular weight polyester (Mw ≥ 163 000 g mol−1) in 15 minutes.

Synthesis, Functionalization, and Controlled Degradation of High Molecular Weight Polyester from Itaconic Acid via ADMET Polymerization

We report a facile strategy for the synthesis, functionalization, and controlled degradation of high molecular weight polyesters based on itaconic acid (IA) and 10-undecenol. A diene monomer, di(10-undecenyl) itaconate (DUI), was synthesized from IA and 10-undecenol by esterification reaction. The acyclic diene metathesis (ADMET) polymerization of DUI was conducted with Grubbs first-generation catalyst (G-I) to afford high molecular weight polyesters (PEIA: P1 and P2). Modification of P1 with three mercaptans (3-mercapto-1,2-propanediol (MP), benzyl mercaptan (BM), and dodecyl mercaptan (DM)) and piperidine (PI) via Michael addition reaction with the itaconate vinyl groups was performed. Quantitative postpolymerization modifications with no degradation of the polyesters were achieved for all the three mercaptans and PI as revealed by NMR and GPC characterizations. One-pot sequential modification of P1 with MP and PI was also successfully conducted. Thermal properties of the modified polyesters were studie...

Facile and Highly Efficient Strategy for Synthesis of Functional Polyesters via Tetramethyl Guanidine Promoted Polyesterification at Room Temperature.

A facile and highly efficient strategy for the synthesis of functional polyesters from 10-undecenoic acid, which is abundantly available and derived from ricin oil, has been successfully achieved using 1,1,3,3-tetramethyl guanidine (TMG) as a promoter at room temperature. The experimental results indicate that high molecular weight polyesters have been obtained and a variety of functional groups, such as alkenyl, alkynyl, nitro, epoxy, hydroxyl, and bromoisobutyrate, can be incorporated as pendant groups. The structures of the obtained polymers were demonstrated by 1H and 13C NMR spectroscopy and their thermal properties were studied by DSC and TGA.

Synthesis and ring-opening copolymerization of cyclic aryl ester dimers

Abstract Two kinds of cyclic aryl ester dimers have been synthesized by reaction of phthaloyl dichloride with bisphenols via interfacial polycondensation. The cyclic dimers readily undergo anionic ring-opening polymerization or copolymerization in the melt by using sodium benzoate as the initiator, producing linear, high molecular weight polyesters. The contents of cyclic dimers in the homopolymers P1, P2, and copolymer P12 are 13.7%, 10.2%, 2.9%, respectively, which indicates that ring-opening copolymerization of cyclic dimers may impel the conversion of cyclic dimers and decrease the content of cyclic dimers in the resulting copolymer. Moreover, the isothermal chemorheology of the ring-opening copolymerization of cyclic dimers indicates that the reactive molten mixture has low shear viscosity and the viscosity increases slowly in the initial stage of ring-opening polymerization.

Acid catalyzed polymerization of macrolactones in bulk and aqueous miniemulsion: Ring opening vs. condensation

Aliphatic polyesters from three macrolactones (pentadecalactone, globalide and ambrettolide) were synthesized by organic acid catalyzed polymerization in bulk and in an aqueous miniemulsion. Two different mechanism of polymerization take place depending on the polymerization media. Relatively high molecular weight polyesters (Mn aprox. 10,000g/mol) were obtained in bulk following a ring opening polymerization mechanism. Interestingly, relatively fast polymerizations were observed which depended in the acid pKa (triflic acid>benzene sulphonic acids>diphenyl phosphate). On the other hand, a condensation mechanism is observed in water miniemulsion leading to oligoesters of aprox. 2000g/mol. This molecular weight limitation prevented these latexes to be suitable for most applications. Interestingly, it is demonstrated that the introduction of unsaturated macrolactones in these aqueous latexes allows subsequent cross-linking leading to cured polyester films.

Study of Seed Polymerized Polyester Emulsion for Chemically Prepared Toner

In full color laser printers and copiers, the performance requirements include high printing speed, fine image quality, and environmental friendliness. Specially designed toners are needed to achieve these requirements. To develop the toner for low-energy fusing, hot-offset resistance, and good storage stability, chemically prepared polyester toner was developed (core-shell typed toner) by emulsion aggregation method. Polyester emulsion is usually made by phase inversion emulsification with organic solvent. Unfortunately higher molecular weight polyesters, which provide resistance against storage stability and hot-offset, have limited solubility in organic solvent. To solve these problems, some cross-linking techniques like urethane reaction and oxazoline-polymer reaction have been developed. But these techniques resulted in disappearance of carboxyl groups which play a role in the dispersion stability of emulsion, so emulsions with small and narrow particle size distribution could not be made. It is a challenge to design resins that have both larger molecular weight and dispersion stability.In this study, to support larger molecular weight and dispersion stability of polyester emulsion at the same time, we introduced seed polymerization which allows radical polymerization inside emulsion without disappearance of carboxyl groups. In addition, it is found that seed polymerization could control the thermal properties of polyester emulsion like storage elastic modulus and glass-transition temperature. With this method, we could design polyester chemically prepared toners having a wider range of thermal properties.

Monitoring biodegradation of poly(butylene sebacate) by Gel Permeation Chromatography, 1H-NMR and 31P-NMR techniques

The increasing use of new generation plastics has been accompanied by the development of standard methods for studying their biodegradability. Generally, test methods are based on the measurement of CO2 production, i.e. the mineralization degree of the tested materials. However, in order to describe the biodegradation process, the determination of the residual amount of tested material which remains in the environment and its chemical characterization can be very important. In this study, the biodegradation in soil of a model polyester (poly(butylene sebacate)) was monitored. Gel Permeation Chromatography and Nuclear Magnetic Resonance (31P-NMR and 1H-NMR) were used in order to obtain information about the polyester structure and the possible by-products that can be found in soil during and at the end of the incubation. The polyester mineralization (i.e. the CO2 production) was tested according to ASTM 5988 standard method for 245 days. When the polyester mineralization was about 21% and 37% (after 78 and 140 days of incubation) and at the end of the process (63% of mineralization, 100% if compared to the cellulose used as reference material), the soil was extracted with chloroform (solvent of the tested substance) and the extracts were analyzed using GPC and NMR acquisitions. The analytical acquisitions showed high molecular weight polyester in soil during the incubation (78 and 140 days): the polyester concentration decreased but its structure remained almost the same with a slow decreasing in molecular weight. At the end of the test (245 days) no film of the polyester could be extracted from the soil: NMR acquisitions and GPC analyses of the extracts suggested a strong degraded structure of the residual polyester. Even if at the end of the process only 63% of carbon had been lost by mineralization, the whole of the added polyester seems to have disappeared after about eight months of incubation, suggesting substantial biomass formation.

Lipase-catalyzed synthesis and characterization of polymers by cyclodextrin as support architecture

Diesters and diols were successfully converted into aliphatic polyesters by enzymatic lipase Candida sp.99-125 catalysis, with β-cyclodextrin acting as supporting architecture (in a similar way as chaperone proteins). No organic solvents were used. The polytransesterification was a much greener process, being solvent-free and without metal residues. Lipase Candida sp.99-125 showed a high catalytic activity for bulkpolymerization of diesters and diols with various numbers of methylene groups in their chains. β-Cyclodextrin encircled the linear polymer chain and maintained the chain in a proper configuration to avoid its coagulation. Lipase initiated the polymerization and β-cyclodextrin threaded onto the polymer chain to control the structure for producing high molecular weight polyesters. From a combination of diesters and diols, polyesters with a high molecular weight of 62,100Da were obtained at 70°C. The corresponding polyesters showed an excellent thermal stability till 350°C and had a strong ability to crystallize with up to 72% crystallinity, contributing to their high storage modulus.

Artificial bacterial degradation and hydrous pyrolysis of suberin: Implications for hydrocarbon generation of suberinite

The organic maceral suberinite is widely believed to be a contributor to immature or low mature oils with Ro<0.5% in some coal and terrigenous sequences. However, its evolution of hydrocarbon generation, especially in the relatively high maturation stage of Ro>0.5%, has not been sufficiently characterized. This issue was addressed herein using periderm cork tissues of the modern angiosperm Quercus suber (suberin), which is a possible bio-precursor of suberinite, in artificial bacterial degradation and hydrous pyrolysis experiments. Integrated studies were conducted, including analyses on the compositions of hydrocarbon yields and the content variations that were generated during the experiments, gas chromatography (GC) analyses of generated oils and spectral fluorescence observations, and Rock-Eval and Fourier Transform Infrared (FTIR) microspectroscopic studies on solid residues. Analytical results indicate that suberin and suberinite have long and complex hydrocarbon generation histories. In general, the hydrocarbon that is generated during bacterial degradation is predominantly gas and present in relatively limited amounts, while the oils mainly are generated during hydrous pyrolysis. Furthermore, the oil generation has two peaks that correspond to Ro of approximately 0.35–0.50% and 0.80–1.10%. In composition, the early generated oil mainly consists of long chain waxy and oxygen containing compounds, while the late generated oil is relatively enriched in aromatic compounds. These features can be ascribed to the chemical nature (e.g., composition and structure) of suberin. It is a type of insoluble and high molecular weight polyester compound that contains large quantities of long chain structure dicarboxylic acids and alcohols. Consequently, the deoxygenization of these compounds can take place under relatively low thermodynamic conditions, generating liquid oil that is dominated by a long chain structure and oxygen-containing waxy compounds. In contrast, the degradation of the phenolic compounds results in the second oil generation peak. Therefore, suberinite has a two stage and relatively long oil generation history and is a good bio-precursor for coal-derived oil generation.

Synthesis of High Molecular Weight Polyesters via In Vacuo Dehydrogenation Polymerization of Diols

The Milstein catalyst has proven to be highly effective for the conversion of alcohols to esters, as well as alcohols and amines to amides and polyamides. We have recently found that the catalyst's range can be extended to very efficient in vacuo dehydrogenation polymerization of α,ω-diols to generate polyesters. The gaseous hydrogen byproduct that is produced is easily removed to drive the equilibrium toward product, which leads to the formation of high molecular weight polymer (M(n) up to 145,000 g mol(-1)). This optimized methodology works well to polymerize diols with a spacer of six carbons or more. Diols with fewer carbons are cyclized to lactone; the dividing point is the dehydrogenation of 1,5-pentanediol, which leads to a mixture of polyester and lactone. Reported herein is the synthesis and characterization of five aliphatic polyesters prepared via this novel dehydrogenation polymerization approach.

Chain extension of adipic acid and (or) succinic acid/butanediol polyesters with 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline) and adipoylbiscaprolactamate combined chain extenders

AbstractThis paper provided an easy and flexible method to synthesize high molecular weight polyesters by polycondensation and chain extension. Low molecular weight polybutylene adipate, polybutylene succinate, and poly(butylene succinate‐co‐butylene adipate) (PBSA) were synthesized through melt condensation polymerization from adipic acid and/or succinic acid with butanediol. The prepolyesters obtained had different amount of COOH and OH terminal groups. Chain extension of them was carried out at 180–240°C using 2,2′‐(1,4‐phenylene)‐bis(2‐oxazoline) and adipoyl biscaprolactamate as combined chain extenders. The influencing factors of the chain extension were studied. At the optimal conditions, chain‐extended polybutylene adipate with Mn up to 39,100, polybutylene succinate with intrinsic viscosity of 0.99 dl/g, and PBSA with intrinsic viscosity from 0.73 to 0.81 dl/g were synthesized. The chain‐extended polyesters were characterized by IR spectrum, 1H NMR spectrum, differential scanning calorimetry, thermogravimetric analysis (TGA), wide angle X‐ray scattering, and tensile test. The thermal analysis showed that chain extension often led to slight decrease of the regularity, the crystallinity, and the melting point. This deterioration of the properties is not harmful enough to impair their thermal properties and obstruct them from being used as biodegradable thermoplastics. The TGA showed that the chain‐extended polyesters were stable with initial decomposition temperature over 354.7°C. The tensile strength of the chain extended PBS and PBSAs with butylene adipate units less than 20 mol% was in the range of 18.95–31.22 MPa. Copyright © 2010 John Wiley &amp; Sons, Ltd.