Synthesis and properties of poly(isosorbide 2,5-furandicarboxylate-co-ε-caprolactone) copolyesters

Bio-based poly(isosorbide 2,5-furandicarboxylate-co-ε-caprolactone) (PIFCL) copolyesters were synthesized from 2,5-furandicarboxylic acid, isosorbide and ε-caprolactone. The obtained copolyesters were characterized by ¹H NMR, ¹³C NMR, intrinsic viscosity, GPC, DSC, TGA and tensile testing. The NMR characterization results confirmed the insertion of lactones units into poly(isosorbide 2,5-furandicarboxylate) (PIF) chains. All PIFCL copolyesters were amorphous with T_{D, 5%} higher than 300 °C. The glass transition temperatures of PIFCLs with FDCA molar ratio from 74% to 45% were within the range of 132.1 °C and 72.4 °C. Tensile testing revealed that introduction of ε-caprolactone into PIF chain imparted PIFCL with excellent mechanical performance, typically, PIFCL polyseter with FDCA molar ratio of 45% had a Young's modulus 858 ± 92 MPa, a tensile strength 44 ± 4 MPa and an elongation at break 480 ± 45%.     

Synthesis, crystallization and hydrolysis of aromatic-aliphatic copolyester: Poly(trimethylene terephthalate)-co-poly(l-lactic acid)

In this study, poly(trimethylene terephthalate)-co-poly(l-lactic acid) (PTT-co-PLLA) copolyesters with different compositions were synthesized by melt polycondensation. The crystal morphologies of PTT-co-PLLA copolyesters were investigated with polarized light microscope (PLM). It was found that PTT-co-PLLA copolyesters exhibited banded spherulites with smaller band spacing at the same degree of super-cooling compared with PTT homopolymer. The PLLA segments in those copolyesters ranged from 0 to 28.4 mol% and did not form crystals during crystallization. Hydrolysis study on PTT homopolymer and PTT-co-PLLA copolyesters was carried out in buffer solutions. PTT-co-PLLA copolyesters represented pronounced hydrolytic degradation, which increased with the content of lactyl units. And it was concluded that degradation of PTT-co-PLLA was mainly attributed to the scission of PLLA segments.     

Synthesis and characterization of amorphous poly(ethylene terephthalate) copolymers containing bis[4-(2-hydroxyethoxy)phenyl]sulfone

Poly(ethylene terephthalate) copolymers (abbreviated as PETS) that contain bis[4-(2-hydroxyethoxy)phenyl]sulfone (BHEPS) were prepared from dimethyl terephthalate (DMT), ethylene glycol (EG) (5-95%) and BHEPS (5-95%). The compositions and microstructures of the copolyesters were determined by ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy, respectively. The thermal behaviors were studied over the entire range of copolymer compositions, using X-ray analysis, differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The molecular weights, optical characteristics and tensile properties of these polymers were also determined. Experimental results indicated that the copolymers had a random microstructure. The intrinsic viscosities of the copolymers ranged from 0.65 to 0.69 dL/g. The copolyesters with BHEPS of <10 mol% were crystallizable, whereas the copolyesters with BHEPS of ?10 mol% were amorphous. Incorporating BHEPS affected the glass-transition temperature (T_g) values of those polymers, from about 81 °C for PETS₅ to 126 °C for PETS₉₅. The optical transmissions exceeded 86% for λ = 400 nm for all of the amorphous polyesters. The tensile modulus and strength of the copolyesters increased with BHEPS. However, they also became brittle and their elongation at break decreased.     

Lipase-catalyzed synthesis of biodegradable copolymer containing malic acid units in solvent-free system

This work is to explore a new route to synthesize functional polyesters bearing pendant hydroxyl groups. The approach is via biocatalyzed direct polycondensation. l-Malic acid, adipic acid and 1,8-octanediol were used as comonomers and lipase Novozym 435 as a biocatalyst. ¹H NMR studies on the structure of the products indicated that Novozym 435 was strictly selective for esterification of l-malic acid carboxyl groups while leaving the hydroxyl groups unchanged. The influences of the monomer feeding ratio, reaction temperature, and reaction time on the molecular weight of the products were investigated. By varying l-malic acid feed ratio in the total monomers from 0 to 20 mol%, the molecular weight (M_W) of the product changed from 9.5 kilo Dalton (kD) to 4.7 kD while reaction was held at 70 °C for 48 h. The maximum M_W could reach 7.4 kD at 80 °C when varying temperature between 70 and 90 °C if l-malic acid is 20 mol% and reaction time is 48 h. At 75 °C the M_W increased from 5.2 kD to 6.6 kD when reaction time was elongated from 48 h to 72 h. However, little change in M_W was observed at 80 and 85 °C when the reaction time was above 48 h. Thermal property of the copolyesters was studied by differential scanning calorimetry (DSC). Increasing the l-malic acid content in copolyesters resulted in melting temperature depression.     

Bio-based copolyesters poly(butylene 2,6-naphthalate-co-butylene furandicarboxylate) derived from 2,5-furandicarboxylic acid (FDCA): Synthesis,characterization, and properties

A series of copolymers poly(butylene 2,6-naphthalate-co-butylene furandicarboxylate) (PBNFs) derived from 2,5-furandicarboxylic acid (FDCA) were synthesized. The molecular weight, microstructures, thermal and mechanical properties were characterized. DSC results show that PBN and PBNF25 can crystallize rapidly. However, the crystallization rates of PBNF50, PBNF75 and PBF are very slow. The T_d,5% and T_d,max values of all polyesters were higher than 360 °C and 390 °C, respectively. Compared with PBN, PBNF25, PBNF50, PBNF75 and PBF exhibited much higher elongation at break (214–295%) and bio-based content (46–100%).     

Synthesis and characterization of aliphatic-aromatic copolyesters based on Cis-1,3-indanediol

This paper reports the synthesis of new copolyesters which incorporate pure isomer cis-1,3-indanediol as well as aliphatic diols HO-(CH₂) _n -OH. 1,3-propanediol, 1,4-butanediol, 1,7-heptanediol and 1,10-decanediol have been used with aromatic diacid terephthaloyl chloride. The stoichiometric proportion of aromatic-aliphatic diols and diacid used is 0.5/0.5/1. All polyesters have been obtained with yields varying from 60 to 84%. The polymers obtained were characterized by various techniques such as FTIR, viscosities, differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction and scanning electron micrograph. All characterizations show that the polymers exhibit semi-crystalline property.     

Study on poly(oxybenzoate-p-trimethylene terephthalate) copolymer

This study examined copolymers synthesized from poly(trimethylene terephthalate) (PTT) and p-acetoxybenzoic acid using solution proton nuclear magnetic resonance (NMR) spectroscopy. Proton NMR spectra showed that these p-oxybenzoate (POB)/PTT copolyesters were almost random copolymers because the preference factor of POB bonded to another POB unit in these copolyesters is close to 1.0 with a POB content between 20 and 80 mol%.The melting and crystallization behaviors of these copolyesters were studied by differential scanning calorimetry (DSC). In the heating DSC scan of the POB rich composition, the endothermic peak is weaker because the enthalpy of fusion decreased due to a melting transition from a crystalline to anisotropy liquid state. Thermogravimetric analysis results indicated that the decomposition temperature (T_d) increased with POB content. The crystalline morphology of the copolyester was further investigated with a polarized optical microscope, indicating that the POB/PTT copolyesters with 60 mol% POB are highly anisotropic in the liquid state.     

Preparation,characterization and thermal degradation study of poly(amide imide)s based on tri-component mixture of PMDA/BTDA,diamines and acid chloride

A series of poly(amide imide)s (PAIs) having alternate (amide–amide) and (imide–imide) units (polymers 1–14 and 22–35), and random distribution of amide-imide linkages (polymers 15–21 and 36–42) were prepared by low temperature solution polymerization of benzene-1,2,4,5-tetracarboxylic dianhydride (PMDA)/benzophenone-3,3′,4,4′-tetracarboxylic dianhydride (BTDA), diamines (cyclic and aromatic) and acid chloride in dimethylforamide. All the polymers were readily soluble in polar aprotic solvents with inherent viscosities in the range of 0.134–0.878. The process of cycloimidization of poly(amide amic acid)s (PAAs) to PAIs was investigated by TGA and FT-IR techniques at four different temperatures i.e., 175, 200, 225, and 260 °C. The rate of cycloimidization was calculated by taking into account the theoretical weight loss (W_T), obtained from [n × M_w (H₂O)/M_w (R_U)] W, where M_w (H₂O) molecular weight of water, W weight of PAA taken for TGA, M_w (R_U) the molecular weight of repeat unit of PAA, n number of water molecules eliminated per repeat unit of PAA upon cycloimidization. For a particular diamine, the extent of percentage cycloimidization at the end of the isothermal heating was higher for PAAs containing trimellitic anhydride chloride (TMAc) unit, irrespective of the nature of the dianhydride and diamine. Thermal and thermooxidative degradation of PAIs was investigated by TGA in nitrogen and oxygen atmosphere. The initial decomposition temperatures (IDT) of polymers are above 260 °C, and vary widely (from 260 to 501 °C) depending upon the structure of the polymer backbone. PAIs containing TMAc exhibited higher thermal stability as compared to those polymers having diacid chloride units, in both N₂/O₂ atmospheres.     

Synthesis and characterization of allyl functionalized poly(α-hydroxy)acids and their further dihydroxylation and epoxidation

In this study, the synthesis of an allyl functionalized aliphatic polyester and the subsequent oxidation of the double bonds was investigated. Allylglycolide (3-allyl-1,4-dioxane-2,5-dione) was synthesized and its homopolymer and copolymers with l-lactide were prepared by ring opening polymerization in the melt using benzyl alcohol and SnOct₂ as initiator and catalyst, respectively. The polymerizations proceeded with high yields and conversions and good control over molecular weights and copolymer composition. The obtained polymers were amorphous materials and their T_g increased with increasing lactide content. Dihydroxylation of the double bonds in poly(allylglycolide) and copolymers with lactide was attempted with osmiumtetroxide/4-methylmorpholine-4-oxide (OsO₄/NMO). However, particularly the polymers rich in allylglycolide could not be isolated after dihydroxylation because they likely underwent degradation during workup. Optimizing the reaction conditions gave partially dihydroxylated copolymers only for copolymers with high lactide content (50 and 75 mol%) with a conversion of the double bonds of only ∼60%. GPC analysis showed that chain scission had occurred during the dihydroxylation reaction and/or workup.The allyl groups of poly(allylglycolide) homopolymers and copolymers with lactide were oxidized using m-chloroperoxy benzoic acid (mCPBA) to yield the corresponding epoxidated polymers in high yield. NMR analysis showed that conversion of the double bonds to epoxides was quantitative, whereas GPC analysis showed that the epoxidation was not associated with chain scission. All epoxidated polymers were amorphous materials with a T_g depending on the composition.     

Biodegradable aliphatic polyesters. Part I. Properties and biodegradation of poly(butylene succinate-co-butylene adipate)

A series of aliphatic homopolyesters and copolyesters was prepared from 1,4 butanediol and dimethylesters of succinic and adipic acids through a two-step process of transesterification and polycondensation. The synthesized polyesters were characterized by means of nuclear magnetic resonance spectroscopy (NMR), gel permeation chromatography (GPC), viscosity measurements, differential scanning calorimetry (DSC), X-ray diffraction (XRD), and mechanical property measurements. The homopolymer poly(butylene succinate) exhibited the highest tensile strength, which decreased with increasing adipate unit content, passed through a minimum at copolyester composition close to equimolarity and then increased towards the value of poly(butylene adipate). It is interesting to note that in contrast to tensile strength, the elongation at break increased for adipate unit content of 20-40 mol%. The biodegradation of the polymers was investigated by soil burial and enzymatic hydrolysis using three enzymes, Candida cylindracea lipase, Rhizopus delemar lipase, and Pseudomonas fluorescens cholesterol esterase. It appears that the key factor affecting material degradation was its crystallinity.     

Enzymatic and microbial biodegradability of poly(ethylene terephthalate) copolymers containing nitrated units

Enzymatic and microbial degradability of poly(ethylene terephthalate) (PET) and PET copolyesters containing 30 mol% of either 5-nitroisophthalic units (PET₇₀NI₃₀) or nitroterephthalic units (PET₇₀NT₃₀) was investigated in laboratory cultures. Two commercial fungal lipases, two bacteria from environmental isolates, and two collection filamentous fungi were tested. The topography of the polymer surface exposed to degradation was characterized by interferometry-confocal microscopy techniques. Biodegradation was estimated by optical and electron microscopy observation, and gel permeation chromatography. Evidence of biodegradation including roughness enhancement, swelling and decrease of the weight-average molecular weight, was only obtained for the case of PET₇₀NT₃₀ cultured with Aspergillus niger. Differences in surface textures were found to be crucial to determine the positive response of this copolyester to biodegradation.     

Synthesis and characterization of biodegradable poly(butylene succinate-co-butylene fumarate)s

A series of aliphatic biodegradable polyesters modified with fumaric residues was synthesized by transesterification in the melt of dimethyl succinate, dimethyl fumarate and 1,4-butanediol. The amount of unsaturation, originating from the fumaric acid residues in the polyesters chains was varied from 5 to 20 mol%. The molecular structure and composition of the polyesters were determined by ¹H NMR spectroscopy. The effects of the content of fumaric residues on the thermal and thermo-oxidative properties of the synthesized polyesters were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis. The degree of crystallinity was determined by DSC and wide angle X-ray scattering. The degrees of crystallinity of the unsaturated copolyesters were reduced, while the melting temperatures were higher in comparison to poly(butylene succinate). Biodegradation of the synthesized copolyesters was estimated in enzymatic degradation tests using a buffer solution with Rhizopus arrhizus lipase at 37 °C. Although the degree of crystallinity of the copolyesters decreases slightly with increasing unsaturation, the biodegradation is not enhanced suggesting that not only the chemical structure and molecular stiffness but also the morphology of the spherulites has an influence on the biodegradation properties. The highest biodegradability was observed for the copolyesters containing 5 and 10 mol% of fumarate units.     

Biodegradable poly(butylene succinate-<Emphasis Type="Italic">co</Emphasis>-butylene dimerized fatty acid)s: Synthesis,crystallization, mechanical properties,and rheology

Poly(butylene succinate-co-butylene dimerized fatty acid) (P(BS-co-BDFA)) copolyesters were synthesized from succinic acid (SA) and dimerized fatty acid (DFA) with 1,4-butanediol (BDO) through a two-step process of esterification and polycondensation. The polyester compositions and physical properties of copolyesters were investigated by GPC, ¹H NMR and ¹³C NMR, DSC, WAXD, DMA, TGA, tensile and rheology test. The melting temperature (T_m), and crystallization temperature (T_c) decreased gradually as the content of DFA monomer increased. P(BS-co-BDFA) copolyesters showed the same crystal structure as the PBS homopolyester. Besides, TGA results indicated that P(BS-co-BDFA)s were of higher thermal stabilities. Moreover, it was found that the synthesized P(BS-co-BDFA)s showed the maximum elongation at break (591%) as the DFA contents were 10 mol%. Rheology analysis indicated that the viscoelastic behavior of the polyesters greatly depended on the molecular weight of polyesters.     

Structure and properties of new polyester elastomers composed of poly(trimethylene terephthalate) and poly(ethylene oxide)

Series of PTT-b-PEO copolymers with different composition of rigid PTT and PEO flexible segments were synthesized from dimethyl terephthalate (DMT), 1,3-propanediol (PDO), poly(ethylene glycol) (PEG, M_n = 1000 g/mol) in a two stage process involving transesterification and polycondensation in the melt. The weight fraction of flexible segments was varied between 20 and 70 wt%. The molecular structure of synthesized copolymers was confirmed by ¹H NMR and ¹³C NMR spectroscopy. The superstructure of these polymers was characterized by DSC, DMTA, WAXS and SAXS measurements. It was observed that domains of three types can exist in PTT-b-PEOT copolymers: semi-crystalline PTT, amorphous PEO rich phase (amorphous PEO/PTT blended phase) and semi-crystalline PEO phase. Semi-crystalline PEO phase was observed only at temperature below 0 °C for sample containing the highest concentration of PEO segment. The phase structure, thermal and mechanical properties are effected by copolymer composition. The copolymers containing 30÷70 wt% of PEO segment posses good thermoplastic elastomers properties with high thermal stability. Hardness and tensile strength rise with increase of PTT content in copolymers.     

Biosynthesis and characterization of novel polyhydroxyalkanoate polymers with high elastic property by Cupriavidus necator PHB4 transformant

We attempted to synthesize novel polyhydroxyalkanoate (PHA) containing new 3-hydroxy-4-methylvalerate (3H4MV) monomer from the transformed strain of Cupriavidus necator PHB⁻4 harboring the PHA synthase gene of Chromobacterium sp. USM2 (phaC_Cs). Novel PHA containing SCL and MCL monomers were successfully synthesized from crude palm kernel oil (CPKO) and isocaproic acid. Results showed that P(3HB-co-1 mol% 3HV-co-3 mol% 3H4MV-co-18 mol% 3HHx) possessed higher thermal stability, higher elastomeric behavior at room temperature and higher ductility than the P(3HB-co-5 mol% 3HHx). The novel PHA film was found to possess an interesting rubber-like elasticity and flexibility property which has not been reported. The soil surface degradation study showed that the novel PHA film was degraded faster than the 3HB homopolymer and copolymer with 5 mol% of 3HHx.     

Synthesis, properties and enzymatic hydrolysis of biodegradable alicyclic/aliphatic copolyesters based on 1,3/1,4-cyclohexanedimethanol

This study synthesizes a series of cyclohexanedimethanol (CHDM)-based alicyclic/aliphatic copolyesters (PBSCs) using succinic acid, 1,4-butanediol and 1,3/1,4-CHDM at various molar ratios to investigate the effects of these compositions on crystallinity, biodegradability and the mechanical properties of PBSCs. The PBSCs were characterized using proton nuclear magnetic resonance, gel permeation chromatography, wide-angle X-ray diffraction, differential scanning calorimeter and thermogravimetric analysis. Biodegradability was evaluated by enzymatic hydrolysis with a lipase from Pseudomonas cepacia. The mechanical properties of PBSCs were determined using a tensile testing machine.Experimental results reveal that the PBSCs containing 1,3/1,4-CHDM in total diol with less than 50 mol% are crystallizable, while those containing 1,3/1,4-CHDM with more than 50 mol% are amorphous. The biodegradability test results suggest that PBSCs can be classified as surface-eroding polymers with a random endo-type scission. Surface hydrophilicity of PBSCs was the predominant effect on enzymatic hydrolysis, not crystallinity.     

Examining thermal stability and structure property relationships in coatings based on linear aromatic poly(methoxy-thiocyanurate)s

A series of copoly(methoxy-thiocyanurate)s is prepared in good yield and purity, and fully characterised. Many of the resulting polymers, formed at room temperature using phase transfer catalysis, can be cast into films with good resilience and thermal stability (some examples suffer practically no mass loss when held isothermally at 190 °C and only display appreciable losses when held continuously at 225 °C). Char yields of 61–64% are achieved in nitrogen depending on backbone structure. Some problems were encountered with solubility, particularly with copolymers, which limited molecular weights analysis, but values of M_n = 7000–10,000 g mol⁻¹ were obtained for the polycyanurate and polythiocyanurate homopolymers. DSC reveals polymerisation exotherms with maxima at 197–207 °C (ΔH_p = 39–48 kJ/mol), which are believed to be due to isomerisation of the (activation energies span 172–205 kJ/mol), since X-ray powder diffraction measurements reveal no evidence of crystalline structure in the resulting product.     

Copolymers of ethyl glycolate and ω–pentadecalactone: Enzymatic synthesis and solid-state characterization

Synthesis of poly(PDL-GA) copolymers is successfully achieved via enzymatic catalysis starting from ω-pentadecalactone and ethyl glycolate. In the copolymers PDL and GA units show a significant tendency to an alternating arrangement. All copolyesters display a high degree of crystallinity (χ_c ≈ 70%) regardless of their composition (GA content: 0–27 mol%). Analysis of melting point depression by the Wendling–Suter model suggests inclusion of GA units in PPDL-type crystals. Accordingly WAXS results show that, with increasing GA unit content, the PPDL unit cell undergoes a gradual increase of c-axis (chain axis) periodicity, compatible with the insertion of GA units within the crystallizing PDL sequences. Poly(PDL-GA) copolymers combine typically hydrophobic (PDL) and hydrophilic (GA) monomers and are promising new tuneable drug-delivery systems for medical applications. In this perspective, poly(PDL-GA) nanoparticles are fabricated and characterized.     

Elastomeric/antibacterial properties in novel random Ricinus communis based-copolyesters

Poly(ricinoleic acid) (PRA), coming from the self-polycondensation of ricinoleic acid (RA), which derives from castor oil, is a very interesting polymer because of its intrinsic antimicrobial activity. However, its mechanical properties are insufficient for whatever application, thus copolymerization is required. In this work, two polyesters based on 1,3 propanediol (PD), such as poly(propylene terephthalate) (PPT) and poly(propylene isophthalate) (PPI), were chosen to prepare random copolyesters containing ricinoleate units. Different content of RA have been tested, such as 10 and 25 mol% respect to the comonomer (terephthalic or isophthalic dimethylester), to evaluate the lowest composition able to confer antibacterial activity. The materials were tested against Staphylococcus aureus and Escherichia coli, and 25 mol% of RA unit resulted to impart antimicrobial activity. Furthermore, thermal properties (DSC and TGA) as well as the elastomeric response of films were investigated. The copolymer PPI/PRA containing 10 mol% of RA presents very high elongation at break, around 1300%. Therefore, by tuning the RA amount it is possible to obtain outstanding elastomeric or antibacterial materials, suitable for textiles and/or film engineering applications.     

Lipase-catalysed degradation of copolymers prepared from ?-caprolactone and dl-lactide

A series of copolymers were prepared by ring-opening polymerization of ?-caprolactone and dl-lactide, using zinc lactate as catalyst. The resulting PCL/PLA copolymers were characterized by various analytical techniques such as NMR, SEC, DSC and X-ray diffraction. The [CL]/[LA] ratios of the copolymers are very close to those in the feed, indicating a good conversion of monomers. The copolymers with CL contents higher than 50% appear semi-crystalline, the crystalline structure being of the PCL-type. Compression moulded polymer films were allowed to degrade in a pH = 7.6 phosphate buffer containing Pseudomonas lipase. Data show that copolymers with CL contents lower than 25% are not degradable and the degradation rate increases with CL content for CL-rich copolymers. Various soluble degradation products are detected in the degradation medium, including CL₁ to CL₃ and LA₁ to LA₄ homo-oligomers, and CL₂LA₁ co-oligomer. The presence of LA homo-oligomers and CL₂LA₁ co-oligomer suggests that Pseudomonas lipase can not only degrade PCL but also LA short blocks along PCL/PLA copolymer chains. On the other hand, little changes of composition are detected during degradation, in agreement with a surface erosion mechanism as shown by ESEM.