Synthesis, characterization and biodegradation of biodegradable-cum-photoactive liquid-crystalline copolyesters derived from ferulic acid

Novel biodegradable-cum-photoactive liquid-crystalline copolyester was prepared by melt polycondensation of ferulic acid (FA), 4-hydroxybenzoic acid (HBA) and d,l-lactic acid (LA) in the presence of acetic anhydride and a transesterification catalyst. The chemical structures and properties of the synthesized copolyesters were characterized by means of viscosity measurements, Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy (¹H NMR), differential scanning calorimetry (DSC), thermogravimetry (TGA), polarizing light microscopy (PLM) and ultraviolet spectroscopy (UV). It was found that modestly increasing LA content and adjusting feed ratios could enhance the solubility and biodegradability of the copolyesters, still retaining the liquid crystallinity. The obtained copolyester could degrade in phosphate buffer solution (pH 7.2) with enzyme proteinase K, and could crosslink by UV-irradiation at ambient temperature.     

Completely amorphous high thermal resistant copolyesters from bio-based 2,5-furandicarboxylic acid

Polyesters from renewable resources with glass transition temperature (T_g) higher than 100°C are crucial in broadening their application range. In this work, a series of high molecular weight copolyesters, poly(butylene bis[4-(2-hydroxyethoxy) phenyl] sulfone 2,5-furandicarboxylate) (PBSF), was synthesized from bis[4-(2-hydroxyethoxy) phenyl] sulfone (BHEPS), bio-based 1,4-butanediol (BDO), and 2,5-furandicarboxylic acid (FDCA) via transesterification. Nuclear magnetic resonance spectroscopy (¹H-NMR and ¹³C-NMR) was used to confirm their chemical structures, composition, and sequence distribution. Characterizations demonstrated that with the increasing content of BHEPS unit, T_g of synthesized polyesters was increased from 38.2°C for PBF to 122°C for PBSF-95, in which the content of BHEPS unit was 95%. However, the weight average molecular weight (M_w) of PBSF was dramatically decreased after the addition of BHEPS, from 95,300 g/mol for PBF to only 9600 g/mol for PBSF-95, which was too low for practical application. Taking molecular weight, T_g, and mechanical properties into account, PBSF-65 was considered to be a promising polyester with M_w of 28,500 g/mol, T_g of 104.7°C, tensile strength of 82 MPa, and elongation-at-break of 98%. Besides, it was a completely amorphous polyester with a transmittance of 89.9% by cutoff at 700 nm. Summarily, PBSF-65 showed great potential to be used as raw material for the manufacture of baby bottles, children's toys, kitchen appliances, and beverage packaging, especially in the case when high transparency and heat resistance are required.     

Effect of monomer composition on the rheological properties of poly(p-oxybenzoate-co-ethylene terephthalate)s

Summary Effect of monomer composition on the dynamic viscoelastic properties and the steady flow properties of thermotropic liquid crystalline poly (p-oxybenzoate-co-ethylene terephthalate)s in the fluid state have been investigated as compared with the isotropic melt of the copolyester including 28 mol% p-oxybenzoate unit (POB). The liquid crystalline copolyesters show the rheological transition temperature, which increases with increasing the content of POB unit. Above the transition temperature, all the thermotropic copolyesters exhibit much higher compliance and much more shear-thinning behavior of the apparent viscosity than the isotropic melt of the non-liquid crystalline copolyester.     

Effects of dispersing agents on dispersity and mechanical properties of carbon black/PET

Three kinds of dispersing agents, all copolyesters, were synthesized from the polycondensation reaction of dimethyl terephthalate (DMT), dimethyl isophthalate (DMI), sebacic acid (SA), and 1,4-butandiol (BD). Copolyester from DMT, SA, and BD was designated as PBTS; from DMT, SA, DMI, and BD as PBTIS; and from DMT, DMI, and BD as PBTI. Carbon black masterbatches were prepared by mixing carbon black into the dispersing agents in a Brabender Plasticorder PLE331. Using single screw extruder, masterbatches were compounded with poly(ethylene terephthalate) in 3 wt% concentration and mechanical properties of the compounds were investigated. Gel permeation chromatography data implied that thermal degradation of polymeric dispersing agents was not very significant. Capillary rheometer tests showed that PBTI has the highest viscosity and shear sensitivity of the three dispersing agents. Volume resistivities of each masterbatch were increased as the rotor rpm of the Brabender and mixing time increased. Transmission electron micrographs showed that dispersion of carbon black was enhanced by increasing the melt viscosity of the dispersing agent. The performance and mechanical characteristics of carbon-black-filled PET compounds depends directly on the dispersion quality of the carbon black in the masterbatch. Mechanical properties of compounds were improved by increasing dispersion of carbon black and increasing numbers of rigid aromatic groups in the copolyester dispersing agent.     

Copolyesters developed from bio-based 2,5-furandicarboxylic acid: Synthesis,sequence distribution,mechanical, and barrier properties of poly(propylene-co-1,4-cyclohexanedimethylene 2,5-furandicarboxylate)s

A series of poly(propylene-co-1,4-cyclohexanedimethylene 2,5-furandicarboxylate)s (PPCFs) with different compositions were synthesized from bio-based aromatic monomer 2,5-furandicarboxylic acid and 1,3-propanediol (PDO), along with 1,4-cyclohexanedimethylene (CHDM). The chemical structure, composition, and sequence distribution of PPCFs were determined by nuclear magnetic resonance (¹H NMR and ¹³C NMR). Results showed that the compositions of copolyesters depended on the feed molar ratio of PDO and CHDM, and all the obtained PPCFs copolyesters had triad component in a random sequential structure. With the addition of CHDM, the gas barrier properties of poly(propylene 2,5-furandicarboxylate) (PPF) deteriorated. However, when the content of CHDM reached 79%, PPCF79 still showed the CO₂ and O₂ barrier improvement factor of 4.5 and 3.25, respectively, which were better than those of poly(ethylene naphthalate), a well-known polymer with barrier property. Besides, PPCF79 showed good performance on tensile modulus, tensile strength, elongation at break, and the crystallization enthalpy was improved from 3.2 J g⁻¹ for PPF to 30.7 J g⁻¹ for PPCF79. It has the potential to serve as a promising bio-based polymer with excellent comprehensive performance. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47291.     

Structure–property relationship of poly(cyclohexane 1,4-dimethylene terephthalate) modified with high trans-1,4-cyclohexanedimethanol and 2,6-naphthalene dicarboxylicacid

A series of novel poly(1,4-cyclohexanedimthylene terephthalate-co-1,4-cyclohxylenedimethylene 2,6-naphthalenedicarboxylate) (PCTN) copolyesters were successfully melt polymerized using different content of trans- or cis-isomers. Before evaluations, the performance properties, their actual chemical composition, chemical structure, and molecular weight were determined using proton nuclear magnetic resonance (¹H-NMR), Fourier transform infrared spectroscopy (FTIR), and intrinsic viscosity (IV) measurements. Thermal studies of obtained copolyesters were carried out using differential scanning calorimetry (DSC). Thermal degradation behaviors were analyzed by thermogravimetric analysis (TGA). Randomly oriented film specimens were developed using a hot-press and their thermal, barrier, dimensional stability, and optical properties were analyzed and compared with conventional poly(ethylene terephthalate) (PET) and poly(ethylene naphthalate) (PEN). The results revealed that glass transition temperature (T_g), melting temperature (T_m), and crystallinity (X_c) of the synthesized copolyesters are increased in a linear trend by increasing the trans-1,4-cyclohexanedimethanol (trans-CHDM) isomers. It was also found that synthesized films had better thermal, barrier, optical, and dimensional stability properties than conventional PET and PEN films. Results clearly indicated that high trans-CHDM isomers significantly improve the performance properties of the fabricated films. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48950.     

Preparation and study of terephthalate copolyester of ethylene glycol and butane-1,4-diol

Summary Random terephthalate copolyesters of ethylene glycol and butane-1,4-diol of various compositions were prepared by trans-esterification of poly(ethylene terephthalate) (PET) with butane-1,4-diol (BD). Proton nuclear magnetic resonance spectroscopy (NMR) was used to elucidate the structure and compositions of copolyesters. The thermal behaviour of the copolyesters were investigated by differential thermal analysis (DTA). Intrinsic viscosities were measured in orthochlorophenol at 30°C.     

基于PA10T的生物基耐高温聚酰胺的合成

采用生物基单体2,5–呋喃二甲酸(FDCA)作为第三单体,与癸二胺、对苯二甲酸(PTA)进行共聚合,合成了相对于聚对苯二甲酰癸二胺(PA10T)(55.6%)具有更高生物基含量的聚对苯二甲酰癸二胺/聚呋喃二甲酰癸二胺(PA10T/10F)共聚物(61.6%)。采用核磁共振波谱(NMR)技术表征了共聚物的结构,明确了共聚合过程中FDCA发生了脱羧反应,导致预聚物端基失衡、增黏产物黏度较低。研究了预聚合温度、排水量、固相增黏温度和氮气流速等反应条件对共聚物结构的影响,确定较优的聚合反应条件为:预聚合温度225℃、排水量70 g、增黏温度235℃以及氮气流速≥0.2 L/min。同时研究了聚合条件对共聚物颜色的影响。     

PEFT共聚酯的热氧化分解行为研究

采用热重(TG)分析法研究2,5-呋喃二甲酸(FDCA)质量分数分别为0,25％,50％,75％,100％的聚对苯二甲酸-2,5-呋喃二甲酸乙二醇共聚酯(PEFT)的热氧化分解行为,使用Kinssinger法、Ozawa法和Coats-Redfen法对PEFT热氧化分解的表观活化能(Ea)和反应机理进行了分析.结果表明...     

Synthesis and characterization of aliphatic copolyesters containing 1,4‐bis[(carboxylethoxy)methyl]cyclohexane

A series of aliphatic copolyesters was synthesized using newly prepared cyclohexane‐based alicyclic diacid, succinic acid and 1,4‐butanediol with various molar ratios, in order to investigate the effects of these compositions on the crystallinity and thermal properties of the aliphatic copolyesters. The structures, average molecular weights and physical properties of the resulting random aliphatic copolyesters were characterized using nuclear magnetic resonance, gel permeation chromatography, differential scanning calorimetry (DSC) and X‐ray diffraction. The results of DSC reveal that thermal and crystallization behaviors depend on the corresponding diacid comonomer (1,4‐bis[(carboxylethoxy)methyl]cyclohexane) content in the aliphatic copolymers. However, the crystalline structures of the aliphatic copolyesters and of poly(butylene succinate) homopolymer are identical. Copyright © 2011 Society of Chemical Industry     

Synthesis and thermal properties of poly(ethylene 2,6‐naphthalate) copolyesters containing modified diacid monomer

A series of poly(ethylene 2,6‐naphthalate) (PEN) copolyesters was synthesized using three monomers (newly prepared 1,4‐bis[(methoxycarbonylethoxy)methyl]benzene, dimethyl 2,6‐naphthalenedicarboxylate, and ethylene glycol) with various molar ratios to investigate the effects of these compositions on thermal properties of the copolyesters. Copolyesters having weight average molecular weights of 11,000–22,000 were obtained by melt polycondensation in the presence of metallic catalysts. The structures and thermal properties of the resulting random PEN copolyesters were characterized by nuclear magnetic resonance, differential scanning calorimetry, thermal‐mechanical analyzer, and X‐ray diffraction analysis. The results of thermal measurements revealed that thermal properties depended on the corresponding new diacid comonomer content of the PEN copolyesters. Nonetheless, the crystal structures of PEN copolyesters and PEN homopolymer are identical. POLYM. ENG. SCI., 54:2641–2644, 2014. © 2013 Society of Plastics Engineers     

Effective biosynthesis of poly(3‐hydoxy‐ butyrate‐co‐4‐hydroxybutyrate) with high 4‐hydroxybutyrate fractions by Wautersia eutropha in the presence of α‐amino acids

BACKGROUND: Biopolymers produced by microbes are in demand as their biodegradable and biocompatible properties make them suitable for disposable products and for potential use as biomaterials for medical applications. The effective microbial production of copolyesters of 3‐hydroxybutyrate (3HB) and 4‐hydroxybutyrate(4HB) with high molar fractions of 4HB unit by a wild‐type Wautersia eutropha H16 was investigated in culture media containing 4‐hydroxybutyric acid (4HBA) and different carbon substrates in the presence of various α‐amino acids. RESULTS: The addition of carbon sources such as glucose, fructose and acetic acid to the culture medium containing 4HBA in the presence of α‐amino acids resulted in the production of random poly(3HB‐co‐4HB) with compositions of up to 77 mol% 4HB unit, but the yields of copolyesters with 60–77 mol% 4HB units were less than 15 wt% of dried cell weights. In contrast, when carbon sources such as propionic acid and butyric acid were used as the co‐substrates of 4HBA in the presence of α‐amino acids, poly(3HB‐co‐4HB) copolyesters with compositions of 72–86 mol% 4HB were produced at maximally 47.2 wt% of dried cell weight (11.3 g L^?1) and the molar conversion yield of 4HBA to 4HB fraction in copolyesters was as high as 31.4 mol%. Further, poly(3HB‐co‐4HB) copolyesters with compositions of 93–96 mol% 4HB were isolated at up to 35.2 wt% of dried cell weights by fractionation of the above copolymers with chloroform/n‐hexane. CONCLUSION: The productivity of copolyesters with over 80 mol% 4HB fractions was as high as 0.146 g L^?1 h^?1 (3.51 g L^?1 for 24 h) by flask batch cultivation. Copyright © 2007 Society of Chemical Industry     

Sequence distribution,thermal properties,and crystallization studies of poly(trimethylene terephthalate‐co‐1,4‐cyclohexylene dimethylene terephthalate) copolyesters

A series of novel poly(trimethylene terephthalate‐co‐1,4‐cyclohexylene dimethylene terephthalate) (PTCT) with various compositions were synthesized by melt polycondensation of 1,3‐propanediol, 1,4‐cyclohexanedimethanol and dimethyl terephthalate. The resulting copolyesters were characterized using ¹³C and ¹H nuclear magnetic resonance. The average length of both trimethylene terephthalate (TT) and cyclohexylene dimethylene terephthalate (CT) sequences varies from 1 to 10, and the chain structure is statistically random. The crystallization was investigated using wide angle X‐ray diffractometer (WAXD) and differential scanning calorimeter. The WAXD patterns can be divided in two groups according to the composition: copolyesters with less than 35 mol % CT content exhibit PTT‐type lattice, and those with CT unit content higher than 42 mol % crystallize with the PCT‐type lattice. The crystallizability of CT sequence is higher than that of TT sequence. Thermodynamic analysis shows that the comonomer is excluded from the PTT‐type or PCT‐type crystal of the copolyesters. The thermal decomposition temperature of copolyesters increases with increasing CT content, and their thermal stability is improved as compared to that of PTT. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Implementing plant‐derived isosorbide and isomannide as comonomers for polyester synthesis: Effects of crystallization properties on optical properties

This article describes the implementation of plant‐derived isosorbide (IS) and isomannide (IM) in the copolymerization modification of poly(ethylene terephthalate). The effects of the two comonomers on the optical, crystallization, and thermal properties of the resulting copolyesters were studied using the following analytical methods: proton nuclear magnetic resonance; differential scanning calorimetry; X‐ray diffraction; thermogravimetry; and ultraviolet‐visible spectroscopy. As comonomers, IS and IM increased the transmittance and reduced the haze of the copolyesters. Moreover, while IM improved the optical properties more than did IS, both monomers improved the optical properties of the copolyesters by lowering its crystallization ability. After the copolymerization modification, the crystallization rate of the copolyesters was reduced, decreasing the crystallinity and crystal size and thereby reducing the light transmission interference. The comonomers also altered the light absorption properties of the copolyesters and conferred a substantial increase in the transmittance of near‐infrared (NIR) wavelengths. These changes in optical properties exhibit the potential of these comonomers for applications in optical materials and NIR detectors. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45444.     

Study on co[poly(butylene terephthalate‐p‐oxybenzoate)] thermotropic copolyester. I. Composition analysis and sequence distribution

Copolyesters made from Poly(butylene terephthalate) (PBT) and p‐acetoxybenzoic acid (PAB) have been examined in solution by proton nuclear magnetic resonance (NMR) spectroscopy. Proton NMR spectra of solutions have shown that the sequence distribution for POB/PBT copolyesters can be described in terms of a probability model in which POB (p‐oxybenzoate) has a chance that is almost random of being bonded to another POB in the copolyesters, with POB content ranging from 20 to 40 mol %. From the experimental data, we can predict that the higher the content of POB in copolyester is, the larger the deviation from randomness of sequence distribution is. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 949–954, 2000     

Efficient Catalytic Oxidation of 5‐Hydroxymethylfurfural to 2,5‐Furandicarboxylic Acid by Magnetic Laccase Catalyst

2,5‐Furandicarboxylic acid (FDCA) is a bio‐based platform chemical for the production of polyethylene furanoate (PEF) and other valuable furanic chemicals. A magnetic laccase catalyst with (2,2,6,6‐tetramethyl‐piperidin‐1‐yl)oxyl (TEMPO) as the mediator has the remarkable capability of oxidizing 5‐hydroxymethylfurfural (HMF) to 2,5‐furandicarboxylic acid (FDCA). Under optimal reaction conditions, a quantitative yield (90.2 %) of FDCA with complete HMF conversion was obtained after 96 h of reaction. More importantly, the magnetic laccase catalyst exhibited good recyclability and stability, maintaining 84.8 % of its original activity following six reuse cycles. This is the first report on the efficient catalytic oxidation of HMF to FDCA by using an immobilized enzyme catalyst.     

Crystallization and properties of poly(ethylene terephthalate) copolymers containing 5-tert-butyl isophthalic units

The influence of incorporating 5-tert-butyl isophthalic units (^tBI) in the polymer chain of poly(ethylene terephthalate) (PET) on the crystallization behavior, crystal structure, and tensile and gas transport properties of this polyester was evaluated. Random poly(ethylene terephthalate-co-5-tert-butyl isophthalate) copolyesters (PET^tBI) containing between 5 and 40 mol% of ^tBI units were examined. Isothermal crystallization studies were performed on amorphous glassy films at 120 °C and on molten samples at 200 °C by means of differential scanning calorimetry. Furthermore, the non-isothermal crystallization behavior of the copolyesters was investigated. It was observed that both crystallinity and crystallization rate of the PET^tBI copolyesters tend to decrease largely with the comonomeric content, except for the copolymer containing 5 mol% of ^tBI units, which crystallized faster than PET. Fiber X-ray diffraction patterns of the semicrystalline PET^tBI copolyesters proved that they adopt the same triclinic crystal structure as PET with the comonomeric units being excluded from the crystalline phase. Although PET^tBI copolyesters became brittle for higher contents in ^tBI, the tensile modulus and strength of PET were barely affected by copolymerization. The incorporation of ^tBI units slightly increased the permeability of PET, but copolymers containing up to 20 mol% of the comonomeric units were still able to present barrier properties.     

5-羟甲基糠醛无碱有氧氧化合成2,5-呋喃二甲酸负载型贵金属催化剂的研究进展

将生物质平台分子5-羟甲基糠醛（5-hydroxymethylfurfural,HMF）高效、绿色地催化转化为更高附加值的2,5-呋喃二甲酸（2,5-furandicarboxylic acid,FDCA）已经成为目前生物质能源转化领域的研究热点。碱性载体负载贵金属催化剂用于HMF无碱氧化为FDCA已经得到广泛研究,并取得了一系列成果。本文综述了水滑石、羟基磷灰石、碳材料、金属氧化物等不同载体负载的贵金属催化剂用于HMF无碱氧化为FDCA的最新进展,详细介绍了各类催化剂的结构性质、催化反应参数及催化活性,重点讨论了催化剂与催化反应的构效关系及催化反应机理等研究工作。最后,指出了今后在HMF转化为FDCA的研究工作中负载型贵金属催化剂的设计开发及机理探究等方面的努力方向。     

Monitoring the functionalization of single-walled carbon nanotubes with chitosan and folic acid by two-dimensional diffusion-ordered NMR spectroscopy

A conjugate between single-walled carbon nanotubes, chitosan and folic acid has been prepared. It was characterized by diffusion ordered two-dimensional hydrogen-1 nuclear magnetic resonance and hydrogen-1 nuclear magnetic resonance spectroscopy which revealed the presence of a conjugate that was generated by the linkage between the carboxyl moiety of the folic acid and the amino group of the chitosan, which in turn was non-covalently bound to the single-walled carbon nanotubes. The obtained diffusion coefficient values demonstrated that free folic acid diffused more rapidly than the folic acid conjugated to single-walled carbon nanotubes–chitosan. The values of the proton signal of hydrogen-1 nuclear magnetic resonance spectroscopy and two-dimensional hydrogen-1 nuclear magnetic resonance spectroscopy further confirmed that the folic acid was conjugated to the chitosan, wrapping the single-walled carbon nanotubes.     

Synthesis and characterization of 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles with two-photon fluorescence properties

Four novel 2,5-bis[4-(2-arylvinyl)phenyl]-1,3,4-oxadiazoles that exhibit strong two-photon absorption and enhanced two-photon excited fluorescence were designed and synthesized based on push-core-pull-core-push  molecules built from embedding electron-transporting 1,3,4-oxadiazole in aromatic conjugated system through Wittig-Horner reaction. Their chemical structures were determined to show trans-vinylene character according to infrared (IR) and ¹H nuclear magnetic resonance (NMR) spectra. A very effective energy transfer from the excited units to the ?-conjugated bridging unit can enhance the two-photon absorption and two-photon fluorescence.