Incorporation of different crystallizable amide blocks in segmented poly(ester amide)s

High molecular weight segmented poly(ester amide)s were prepared by melt polycondensation of dimethyl adipate, 1,4-butanediol and a symmetrical bisamide-diol based on ε-caprolactone and 1,2-diaminoethane or 1,4-diaminobutane. FT-IR and WAXD analysis revealed that segmented poly(ester amide)s based on the 1,4-diaminobutane (PEA(4)) give an α-type crystalline phase whereas polymers based on the 1,2-diaminoethane (PEA(2)) give a mixture of α- and γ-type crystalline phases with the latter being similar to γ-crystals present in odd-even nylons. PEA(2) and PEA(4) polymers with a hard segment content of 25 or 50 mol% have a micro-phase separated structure with an amide-rich hard phase and an ester-rich flexible soft phase. All polymers have a glass transition temperature below room temperature and melt transitions are present at 62-70 °C (T_m,1) and at 75-130 °C (T_m,2) with the latter being highest at higher hard segment content. The two melt transitions are ascribed to melting of crystals comprising single ester amide sequences and two or more ester amide sequences, respectively. These polymers have an elastic modulus in the range of 159-359 MPa, a stress at break in the range of 15-25 MPa combined with a high strain at break (590-810%). The thermal and mechanical properties are not influenced by the different crystalline structures of the polymers, only by the amount of crystallizable hard segment present.     

Synthesis and characterization of poly(ester amide)s containing crystallizable amide segments

High molecular weight segmented poly(ester amide)s were prepared by melt polycondensation of 1,4-butanediol, dimethyl adipate and a preformed bisamide-diol based on 1,4-diaminobutane and ε-caprolactone. By varying the ratio of the bisamide-diol and 1,4-butanediol, a series of polymers was obtained with a hard segment content between 10 and 85 mol%. FT-IR and WAXD analysis revealed that the poly(ester amide)s crystallize in an α-type phase similar to the α-phase of even-even nylons. These polymers all have a micro-phase separated structure with an amide-rich hard phase and an ester-rich flexible soft phase. The polymers have a low and a high melt transition, corresponding with the melting of crystals comprising single ester amide sequences and two or more ester amide sequences, respectively. The low melt transition is between 58 and 70 °C and is independent of polymer composition. By increasing the hard segment content from 10 to 85 mol% the high melt transition increased from 83 to 140 °C while the glass transition temperature increased from −45 to −5 °C. Likewise, the elastic modulus increased from 70 to 524 MPa, the stress at break increased from 8 to 28 MPa while the strain at break decreased from 820 to 370%. Thermal and mechanical properties can thus be tuned for specific applications by varying the hard segment content in these segmented polymers.     

Synthesis,characterization and properties of a castor oil modified biodegradable poly(ester amide) resin

A biodegradable poly(ester amide) resin was synthesized from N,N-bis(2-hydroxy ethyl) fatty amide of castor oil with maleic anhydride, phthalic anhydride and isophthalic acid (100:30:35:35 mole ratio) by the polycondensation process. The fatty amide of the oil was obtained for the first time with 95% yield. The chemical structure of the synthesized resin was characterized by spectroscopic techniques like FTIR, ¹H NMR and ¹³C NMR. Various physical properties such as acid value, saponification value, iodine value, specific gravity and viscosity of the resin were also determined. Further the rheological behavior, studied in the steady shear mode showed shear thinning behavior of the resin. The epoxy cured poly(ester amide) thermoset using poly(amido amine) hardener exhibited better properties than with the cycloaliphatic amine hardener cured system. TGA studies also revealed higher thermal stability of the former system than the latter. In vitro-biodegradation study of the poly(ester amide) thermoset using Pseudomonas aeruginosa and Bacillus subtilus bacteria revealed superior biodegradability of the thermoset using the former bacterial strain. Excellent chemical resistance against various chemical media including alkali was observed for epoxy-poly(amido amine) cured poly(ester amide) resin over epoxy-cycloaliphatic amine one. The epoxy-poly(amido amine) cured poly(ester amide) thermoset thus has the potential to be used as surface coating material.     

Synthesis, characterization and biodegradation of poly(ester amide)s based hydrogels

A series of new biodegradable hybrid hydrogels were designed and fabricated from a new family of amino acid-based functional poly(ester amide) (PEA-AG) and commercial poly(ethylene glycol) diacrylate (PEG-DA) or Pluronic diacrylate (Pluronic-DA) by UV photocrosslinking. These biodegradable hybrid hydrogels were characterized in terms of equilibrium swelling ratio (Q_eq), compression modulus by dynamic mechanical analysis (DMA), and interior morphology by scanning electron microscope (SEM). Both the precursors’ chemical structures and feed ratio had significant effect on the properties of the hybrid hydrogels. All these hybrid hydrogels had a three-dimensional porous network structure. The hydrophobicity, crosslinking density and mechanical strength of the hybrid hydrogels increased with an increase in allylglycine (AG) content in the PEA-AG, but the swelling and pore size of the hybrid hydrogels decreased. The biodegradation rate of these hybrid hydrogels in an enzyme (α-chymotrypsin) solution was faster than in a pure PBS buffer control, and the biodegradation rate increased with an increase in α-chymotrypsin concentration and allylglycine content.     

Synthesis of biodegradable amino‐acid‐based poly(ester amide)s and poly(ether ester amide)s with pendant functional groups

A new family of biodegradable amino‐acid‐based poly(ester amide)s (AA–PEAs) and amino‐acid‐based poly(ether ester amide)s (AA–PEEAs) consisting of reactive pendant functional groups (? COOH or ? NH₂) were synthesized from unsaturated AA–PEAs and AA–PEEAs via a thiol–ene reaction in the presence of a radical initiator (2,2′‐azobisisobutyronitrile). The synthetic method was a one‐step reaction with near 100% yields under mild reaction conditions. The resulting functional AA–PEA and AA–PEEA polymers were characterized by Fourier transform infrared spectroscopy, NMR, and differential scanning calorimetry. These new functional AA–PEA and AA–PEEA derivatives had lower glass‐transition temperatures than the original unsaturated AA–PEA and AA–PEEA polymers, and their solubility in some organic solvents also improved. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

聚丙烯/聚醚酯酰胺共混纤维的研制

用聚乙二醇与己二酸反应合成聚醚酯,再用聚醚酯与己内酰胺反应得到聚醚酯酰胺。将聚醚酯酰胺与聚丙烯共混并纺丝得到聚丙烯/聚醚酯酰胺共混纤维;研究了聚醚酯与聚醚酯酰胺的结构和热性质;考察了共混纤维性能。结果表明:聚醚酯含量增加,聚醚酯酰胺的熔点下降,结晶温度升高;共混纤维的抗静电性和回潮率随聚醚酯酰胺含量和聚醚酯含量的增加而增强;共混纤维有很好的可染性,但强度略低。     

含锌聚醚酯酰胺的热性能研究

以氧化锌、脂肪族二羧酸、聚乙二醇为原料合成含锌聚醚酯(PEEM),再将PEEM与聚己内酰胺低聚合物反应,制备含锌聚醚酯酰胺(PEEAM),借助差示扫描量热法(DSC)、热重(TG)分析,研究了PEEAM的热性能。结果表明:PEEAM呈双熔融和双结晶峰,随PEEM含量增加,PEEAM中PEEM链段的熔融温度降低,熔融热焓增大,聚酰胺链段的熔融温度略有下降,结晶放热和结晶温度随PEEM含量变化有最小值;PEEAM中含脂肪族二羧酸种类不同,其相应的熔融温度、熔融热焓、结晶温度及结晶放热不同,没有明显规律可循。脂肪族二羧酸种类对PEEAM的初始降解温度和最大质量损失温度没有明显影响。PEEM含量增大,PEEAM的热失重速率增大。     

以季戊四醇为核的超支化不饱和聚酰胺酯的合成

以顺丁烯二酸酐（MA）和二乙醇胺（DEA）为原料合成超支化不饱和聚酰胺酯AB2型单体。通过季戊四醇和AB2型单体进行酯化反应合成支化不饱和聚酰胺酯HBP。考查了反应温度、催化剂用量、反应时间对反应产率的影响。最佳工艺条件为：温度140℃,反应时间5h,催化剂对甲苯磺酸用量为反应物量的1.5%。     

Infrared spectroscopic studies of a nematic liquid crystalline poly(ester amide) in the solid phase

Infrared spectroscopy has been used to study the hydrogen bonding conditions in a nematic liquid crystalline poly(ester amide). The results showed that the material formed interchain hydrogen bonding as a result of the inclusion of amide groups in the polymer chains. The hydrogen bonding was found to be stable in the temperature range studied (up to 150°C). However, the studies suggested that the hydrogen bond strength was weaker than in polyamide and did not appear to affect the mechanical properties of the material significantly.     

Hydrogen bonds in poly(ester amide)s and their model compounds

The hydrogen bonds in poly(ester amide)s and their model compounds were investigated using infra-red spectroscopy in the temperature range from 20 to 240°C. It was found that in the polymers investigated both amide—amide and amide—ester hydrogen bonds were formed, while in the corresponding model compounds only amide-amide hydrogen bond formation was observed.     

Studies on the biodegradation and biocompatibility of a new poly(ester amide) derived from L-alanine

A new poly(ester amide) derived from L -alanine has been synthesized and characterized. The polymer has good fiber- and film-forming properties, as well as other characteristics like thermal stability and solubility in chloroform, which enhance its processing facilities. Degradation studies show that both pH and temperature influence in the hydrolisis rate that takes mainly place through the ester linkages. Degradation was also studied by using different enzymes. Results indicated that papain was the most efficient of these, and that the hydrolysis to water-soluble products could be attained in a few days. Basal cytotoxicity was assayed using a mouse L929 fibroblast permanent cell line. The MTT viability test was performed with liquid extract of the material (50 days, 37°C). An attachment and proliferation screening study with intact material was also carried out. No cytotoxic responses were detected, in either assay, after a 24- and 48-h incubation period with the cells. After 72 h a slight cytotoxicity was detected in the polymer material, while a more significant one was detected in the material extract. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1537–1549, 1998     

Bio-degradable vegetable oil based hyperbranched poly(ester amide) as an advanced surface coating material

Vegetable oil based hyperbranched poly(ester amide) (HBPEA) has enormous importance because of its unique characteristics. Thus the synthesis of HBPEA using N,N′-bis(2-hydroxy ethyl) castor oil fatty amide, maleic anhydride, phthalic anhydride and isophthalic acid as A₂ monomers and diethanol amine, as B₃ monomer was reported for the first time. The chemical structure of the synthesized resin was characterized by Fourier transform infrared (FTIR) and nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopic techniques. The degree of branching (DB) (as vouched by ¹H NMR analysis) and initial degradation temperature were found to increase with the increment in B₃ monomer content. Resins with 5 and 10 wt% of B₃ monomer showed shear thinning behavior while rheopectic nature of HBPEA with 15 wt% of B₃ content was observed. The evaluation of tensile strength, elongation at break, abrasion resistance, adhesion strength, scratch hardness, gloss, impact strength and chemical resistance complemented by microbial and lipolytic degradation forward the epoxy cured thermosets as advanced biodegradable surface coating materials.     

超支化聚酰胺酯对聚乳酸增韧改性的研究

采用熔融共混的方法,用生物可降解的超支化聚酰胺酯(HBP)对聚乳酸(PLA)进行增韧改性,制备出具有良好韧性的PLA复合材料。对不同HBP含量的共混物的红外光谱、热性能和力学性能进行了测试和分析。红外光谱显示PLA和HBP间存在氢键作用。HBP的加入使PLA的结晶度从30.99%降低到18.58%。当HBP含量增加到10%时,PLA共混物的拉伸强度略有提高,且断裂伸长达到43.06%。结果表明:HBP的加入对PLA起到了很好的增韧作用。     

Electrospinning of Novel Poly(ester amide)s

Novel PEAs derived from 1,4‐butanediol, dimethyl adipate and a preformed α,ω‐amino alcohol were synthesised and successfully electrospun from solution. The effects of increasing the ratio of amide/ester groups in the copolymer, polymer concentration, solvent mixtures and applied voltage on fibre morphology and diameter were investigated. The obtained fibres (diameter 180–450 nm) were randomly oriented. The fibre quality and homogeneity increased with increasing amide concentration. The solvent mixture CHCl₃/HCOOH gave the best electrospinning results. The ultra‐fine fibres were characterised using SEM, DSC and FT‐IR, showing that the electrospun fibres are amorphous as compared to the pristine samples. These fibres are potential candidates for use as scaffolds in tissue engineering.

     

Thermal cross-link behavior of an amorphous poly (para-arylene sulfide sulfone amide)

Cross-link behavior of an amorphous poly (para-arylene sulfide sulfone amide) synthesized via low temperature solution polycondensation was observed for the first time, when the polymer was subject to a series of thermal curing at 260 °C in air condition. The formation of cross-link network was demonstrated by the DSC and TGA results that T_g of the polymer enhanced from 259.17 °C to 268.89 °C, and the 1% weight loss temperature increased remarkably from 243.75 °C to 345.87 °C. EPR analysis further suggested that two kinds of free radicals, CO and C, induced by thermal curing were responsible for this cross-link behavior. According to FT-IR spectrum, the origin of these free radicals was confirmed as amide CO group in the polymer backbone. The cross-linking type was attributed to conventional radical cross-link reaction and the cross-link mechanism was discussed in detail subsequently.     

Poly(ester amide)s derived from 1,4-butanediol, adipic acid and 6-aminohexanoic acid. Part II: composition changes and fillers

BAK poly(ester amide)s differing in the amide/ester ratio have been synthesized and characterized, considering spectroscopic data and both thermal and mechanical properties. Degradability under different media (water at 70 °C, acid or enzymatic catalysis at 37 °C) has also been studied by evaluating the changes in intrinsic viscosity, in the NMR spectra and in the surface texture of samples. The use of chain extenders, such as hexamethylene diisocyanate and 1,3-butadiene diepoxide, has been investigated and the optimal reaction conditions are reported here. Changes on mechanical properties due to the incorporation of biodegradable reinforces have also been evaluated. Finally, the synthesis and determination of thermal properties of related poly(ester amide)s constituted by glutaric or succinic acid instead of adipic acid have been investigated.     

Copolymers of unsaturated and saturated poly(ether ester amide)s: Synthesis,characterization, and biodegradation

A series of biodegradable random unsaturated/saturated poly(ether ester amide)s copolymers (USPEEAs) were synthesized by an active solution polycondensation of unsaturated and saturated dicarboxylic acid‐based diester monomers with diamine salts of phenylalanine and saturated oligo(ethylene glycol) (OEG). These USPEEA copolymers were obtained with fairly good yields in DMA solvent. The chemical structures of the USPEEA copolymers were confirmed by both IR and NMR spectra. The molecular weights (M_n and M_w) of USPEEAs measured by GPC ranged from 3 to 27 kg/mol with the molecular weight distribution (MWD) ranging from 1.52 to 2.13. USPEEA copolymers obtained had T_g lower than that of the pure UPEEAs but higher than that of pure saturated poly(ether ester amide)s (SPEEA). An increase in the unsaturated component in USPEEAs led to an increase in their T_g. A preliminary in vitro biodegradation property of USPEEA copolymers were investigated in both pure PBS buffer and α‐chymotrypsin solutions. The USPEEA copolymers showed a pronounced weight loss in enzyme solutions, but a smaller weight loss in a pure PBS. The biodegradation rates of USPEEA copolymers in α‐chymotrypsin solution were much slower than those of pure PEEAs. Therefore, upon adjusting monomers feed ratio, USPEEA copolymers could have controlled chemical, physical, and biodegradation properties. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of novel aromatic poly(ester amide)s containing pendant trifluoromethylphenoxy groups

A new diamine monomer, 1,4-bis(4-aminophenoxycarbonyl)-2-(4-trifluoromethylphenoxy)benzene containing the trifluoromethyl and ester groups, was prepared from 2-(4-trifluoromethylphenoxy)terephthalyol chloride and 4-nitrophenol in two steps. Then, a series of novel aromatic poly(ester amide)s containing pendant trifluoromethylphenoxy groups with inherent viscosities of 0.51–1.14 dL/g have been prepared by low-temperature solution polycondensation from this diamine with various aromatic diacid chlorides. All the poly(ester amide)s are amorphous and readily soluble in many organic solvents such as N,N-dimethylacetamide (DMAC) and dimethyl sulfoxide. Tough and flexible polymer films cast from DMAc solutions have tensile strengths of 89–114 MPa, elongations at break of 5.8–8.8%, and initial moduli of 2.2–3.2 GPa. These poly(ester amide)s show glass transition temperatures between 166 and 256°C, 10% weight loss temperatures ranging from 395 to 445°C, and char yields higher of 46–56% at 800°C in nitrogen, and also exhibit low dielectric constants ranging from 3.31 to 3.52 (1 MHz), and high transparency with an ultraviolet–visible absorption cut-off wavelength in the 362–380 nm range. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012