Synthesis and characterization of poly(ethylene‐co‐trimethylene terephthalate)s

Taking advantage of a melt polycondensation process, a series of copolyesters composed of pure terephthalate acid (PTA), ethylene glycol (EG), and 1,3‐propanediol (1,3‐PDO) were synthesized. The component, molecular weight, molecular weight distribution, and thermal properties of the copolymers were characterized. The results show that the contents of trimethylene terephthalate (TT) units in the resulting copolyesters are higher than PDO compositions in original diol. Oligomer content in the copolyesters varies with the compositions and attains a minimum value when the TT ingredient is 49.52 mol %. The glass transition temperature (T_g) of the copolyesters varies from 78.5°C for PET (polyethylene terephthalate) to 43.5°C for PTT (polytrimethylene terephthalate) and decreases monotonically with the components. The copolyesters are amorphous copolymers when TT content is in the range of 32.4–40.8 mol %, as calculated from the melting enthalpy (ΔH_m) measured via differential scanning calorimetry. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1511–1521 2006     

Competitive interaction of polyanions and 2-(4′-hydroxyphenylazo) benzoic acid with bovine serum albumin

The binding of the anionic dye 2-(4′-hydroxyphenylazo) benzoic acid (HABA) to bovine serum albumin (BSA) at pH 6.0–7.5 was studied by spectrophotometry. The values of the dissociation constants were obtained by use of a modified Langmuirtype equation for HABA. Competitive binding of the polyanions sodium poly(styrene sulfonate) (PSSNa), potassium poly(vinyl sulfate) (PVSK), poly(acrylic acid) (PAA), and poly(methacrylic acid) (PMAA), with HABA to BSA were evaluated by variations in the difference spectra of BSA-HABA-polymer systems.     

Synthesis and characterization of aromatic polyesters and copolyesters from 4,4′‐(1‐hydroxyphenylidene)diphenol and 4,4′‐(9‐fluorenylidene)diphenol

Two isophthalic polyesters from 4,4′‐(1‐hydroxyphenylidene)diphenol (BAP/ISO) and 4,4′‐(9‐fluorenylidene)diphenol (BF/ISO), and three different copolyesters containing 75, 50, and 25 mol % of BAP/ISO were synthesized by interfacial polycondensation. This preparation method yielded polymers and copolymers that produced flexible and transparent films when they were cast from solution. Proton NMR spectrometry studies showed that the isophthalic copolyesters were obtained as random copolymers with differences in comonomer composition no larger than 2.5 mol % with respect to the expected compositions. Wide‐angle X‐ray diffraction measurements indicated that all the polyesters and copolyesters were amorphous. The copolyesters showed amorphous patterns with maxima that fell between those of the polyesters. It was also found that thermal properties such as glass‐transition temperature, onset of decomposition temperature, thermal stability, dynamic mechanical storage modulus, and maximum on the α‐transition of the damping factor tan δ of BF/ISO were higher than those of BAP/ISO. The values of these thermal properties in the copolyesters fell between those of the polyesters and were dependent on the amounts of BF/ISO and BAP/ISO present in the copolyester in a linear fashion. Therefore, the thermal properties of a given copolyester can be predicted directly from the comonomers' composition. Overall, it shows that the interfacial polycondensation method is suitable to obtain these copolyesters in a controlled manner and that their properties can be tailored to be between those of the homopolyesters. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2515–2522, 2002     

Syntheses of poly(lactic acid)‐poly(ethylene glycol) serial biodegradable polymer materials via direct melt polycondensation and their characterization

Directly starting from lactic acid (LA) and poly(ethylene glycol) (PEG), biodegradable material polylactic acid‐polyethylene glycol (PLEG) was synthesized via melt copolycondensation. The optimal synthetic conditions, including prepolymerization method, catalyst kinds and quantity, copolymerization temperature and time, LA stereochemical configuration, feed weight ratio m_LA/m_PEG and M_n of PEG, were all discussed in detail. When D ,L ‐LA and PEG (M_n = 1000 Da) prepolymerized together as feed weight ratio m_{D ,l‐LA}/m_PEG = 90/10, 15 h copolycondensation under 165°C and 70 Pa, and 0.5 wt % SnO as catalyst, gave D ,L ‐PLEG1000 with the highest [η] of 0.40 dL/g, and the corresponding MW was 41,700 Da. Using L ‐LA instead of D ,L ‐LA, 10 h polymerization under 165°C and 70 Pa, and 0.5 wt % SnO as catalyst, gave L ‐PLEG1000 with the highest [η] of 0.21 dL/g and MW of 15,600 Da. Serial D ,L ‐PLEG with different feed weight ratio and M_n of PEG were synthesized via the simple and practical direct melt copolycondensation, and characterized with FTIR, ¹H NMR, GPC, DSC, XRD, and contact angle testing. D ,L ‐PELG not only had higher MW than PDLLA, PLLA and L ‐PELG, but also better hydrophilicity than PDLLA. The novel one‐step method could be an alternative route to the synthesis of hydrophilic drug delivery carrier PLEG instead of the traditional two‐step method using lactide as intermediate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 577–587, 2006     

Two novel Zn(II) coordination polymers based on trigonal ligand: 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine

Two novel Zn(II) coordination polymers, [Zn₅(pytpy)₈(fum)₄(H₂O)₄(OH)₂]_n · n(CH₃OH) · 2n(H₂O) (1) and [Zn₃(pytpy)₄ (btc)₂]_n · 2n(H₂O) (2) (pytpy = 4′-(4-pyridyl)-3,2′:6′,3″-terpyridine, H₂fum = fumaric acid, H₃btc = 1,3,5-benzenetricarboxylic acid) have been hydrothermally synthesized and structurally characterized. Complex 1 is a 2D layer structure, which is constructed from linear pentanuclear Zn(II) subunits interconnected via bidentate-bridging pytpy ligands and tridentate-bridging fum²⁻ anions. Complex 2 is a 3D network structure, μ₂-pytpy ligands link the layers based on the heart-like hexanuclear subunits to form the 3D network. Both complexes show strong fluorescence emission upon excitation at 310 nm in solid state. Additionally, these two complexes possess great thermal stabilities, especially for 2, the framework is stable up to 350 °C.     

Synthesis and characterization of novel aromatic poly(amide‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl or 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic diamines

New aromatic diimide‐dicarboxylic acids having kinked and cranked structures, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b), were synthesized by the reaction of trimellitic anhydride with 2,2′‐bis(4‐aminophenoxy)biphenyl (1a) and 2,2′‐bis(4‐aminophenoxy)‐1,1′‐binaphthyl (1b), respectively. Compounds 2a and 2b were characterized by FT‐IR and NMR spectroscopy and elemental analyses. Then, a series of novel aromatic poly(amide‐imide)s were prepared by the phosphorylation polycondensation of the synthesized monomers with various aromatic diamines. Owing to structural similarity, and a comparison of the characterization data, a model compound was synthesized by the reaction of 2b with aniline. The resulting polymers with inherent viscosities of 0.58–0.97 dl g^?1 were obtained in high yield. The polymers were fully characterized by FT‐IR and NMR spectroscopy. The ultraviolet λ_max values of the poly(amide‐imide)s were also determined. The polymers were readily soluble in polar aprotic solvents. They exhibited excellent thermal stabilities and had 10% weight loss at temperatures above 500 °C under a nitrogen atmosphere. Copyright © 2003 Society of Chemical Industry     

Synthesis and properties of fluorinated aromatic poly(amide imide)s based on 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone and various bis(trimellitimide)s

A CF₃‐containing diamine, 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone ( 2 ), was synthesized from 4,4′‐dihydroxybenzophenone and 2‐chloro‐5‐nitrobenzotrifluoride. Imide‐containing diacids ( 3 and 5B_a – 5B_g ) were prepared by the condensation reaction of aromatic diamines and trimellitic anhydride. Then, two series of novel soluble aromatic poly(amide imide)s (PAIs; 6A_a – 6A_k and 6B_a – 6B_g ) were synthesized from a diamine ( 4A_a – 4A_k or 2 ) with the imide‐containing diacids ( 3 and 5B_a – 5B_g ) via direct polycondensation with triphenyl phosphate and pyridine. The aromatic PAIs had inherent viscosities of 0.74–1.76 dL/g. All of the synthesized polymers showed excellent solubility in amide‐type solvents, such as N‐methyl‐2‐pyrrolidone and N,N‐dimethylacetamide (DMAc), and afforded transparent and tough films by DMAc solvent casting. These polymer films had tensile strengths of 90–113 MPa, elongations at break of 8–15%, and initial moduli of 2.0–2.9 GPa. The glass‐transition temperatures of the aromatic PAIs were in the range 242–279°C. They had 10% weight losses at temperatures above 500°C and showed excellent thermal stabilities. The 6B series exhibited less coloring and showed lower yellowness index values than the corresponding 6A series. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:3641–3653, 2006     

聚乳酸立构复合物的合成与表征

采用直接熔融缩聚法制备不同分子量特征的聚乳酸预聚物,将分子量相近的PLLA和PDLA预聚物等量混合,经过熔融共混后再进行固相聚合,制备得到聚乳酸立构复合物.结果表明:sc-PLA与两种PLA预聚物相比,熔点提高50℃左右,通过固相聚合PLA的分子量也得到显著提高.该方法工艺简单,产物纯净,是改善聚乳酸耐热性的一种有效途径.     

Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds

A series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry     

Structure and properties of melt-extruded laRC-IA (3,4′-ODA 4,4′-ODPA) polyimide fibers

LaRC-IA polyimide fibers were extruded from the melt and drawn. The fibers were characterized by sonic pulse propagation, polarized optical microscopy, calorimetric analysis, X-ray diffraction, and tensile testing. When the amorphous, essentially isotropic, as-extruded filaments were heated slowly in a calorimeter, no “cold” crystallization could be detected. However, when these filaments were drawn at temperatures above the T_g of the polymer, they crystallized rapidly to produce oriented semicrystalline structures. The consequent increases in modulus and strength were significant, with the properties reaching the levels of commercial fibers of intermediate tenacity. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1215–1222, 1999     

4-(4-苯基丁氧基)苯甲酸的合成研究

以4-氯-1-丁醇为原料,三氯化铝为催化剂,三氯甲烷为溶剂,经四步反应生成4-(4-苯基丁氧基)苯甲酸,确定了关键反应步骤的反应条件、反应温度和反应时间,产品总收率达到54%,产品含量达到99.5%。     

Crystal structure of 10-chloro-3,3,3′,3′-tetramethyl-1,1′-diethylindodicarbocyanine

The single crystal X-ray structure of indodicarbocyanine dye has been determined at room temperature and its chemical structure confirmed. A unit cell consists of four organic cations, four iodide anions and four H₂O molecules; H₂O molecules are involved into the unit cell during the crystallization. Hydrogen bond interaction probably exists between the iodide anion and a H₂O molecule. The N-atoms are in a cis-type arrangement with respect to the methine chain, and the distributions of bond lengths indicate extended delocation of π-electrons. The molecules are stacked face-to-face to form a column along the b axis direction, and some dimerization is observed.     

Biodegradable polymers based on renewable resources. III. copolyesters composed of 1,4:3,6‐dianhydro‐D‐glucitol, 1,1‐bis(5‐carboxy‐2‐furyl)ethane and aliphatic dicarboxylic acid units

Various copolyesters were synthesized by bulk polycondensation of the respective combinations of 1,4;3,6‐dianhydro‐D ‐glucitol (1) as the diol component and 1,1‐bis[5‐(methoxycarbonyl)‐2‐furyl]ethane (3b) and seven dimethyl dialkanoates with methylene chain lengths of 4, 5, 6, 7, 8, 10, and 12 (4a–4g) as the dicarboxylic acid components. Most of the copolyesters were amorphous, while a copolyester composed of 1, 3b, and dodecanedioic acid (4g) (3b:4g = 25:75) units as well as homopolyesters derived from 1 and azelaic acid (4d), sebacic acid (4e), and dodecandioic acid (4g), respectively, were partially crystalline. All these homo‐ and copolyesters were soluble in chloroform, dichloromethane, pyridine, trifluoroacetic acid, and m‐cresol. The number‐average molecular weights of these polyesters were estimated to be in the range of 10,000–20,000 by SEC using chloroform as an eluent and standard polystyrene as a reference. The biodegradability of these copolyesters was assessed by enzymatic degradation using four different enzymes in a phosphate buffer solution at 37°C and by soil burial degradation tests in composted soil at 27°C. In general, biodegradability of the copolyesters decreased with increase in the difuran dicarboxylate 3b content. Copolyesters containing sebasic acid 4e units showed higher biodegradability. Soil burial degradation in the soil that was treated with antibiotics, together with electron microscopic observation, indicated that actinomycetes are mainly responsible for the degradation of the copolyesters containing 3b units in the present soil burial test. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3342–3350, 1999     

Direct synthesis of poly(4′‐oxy‐4‐biphenylcarbonyl) and poly(2‐oxy‐6‐naphthoyl) under nonstoichiometric conditions

Direct synthesis of poly(4′‐oxy‐4‐biphenylcarbonyl) (POBP) and poly(2‐oxy‐6‐naphthoyl) (PON) was examined by polycondensation of 4′‐hydroxy‐4‐biphenylcarboxylic acid (HBPA) and 2‐hydroxy‐6‐naphthoic acid (HNA) in the presence of 4‐ethoxybenzoic anhydride or 2‐naphthoic anhydride as condensation reagents. Polymerizations were carried out at 320 °C in aromatic solvents and liquid paraffin. POBP, having a number‐average degree of polymerization (DPn) of 38, was obtained as plate‐like crystals at the molar ratio of HBPA and anhydride of 50 mol%. PON was also obtained as plate‐like crystals but the DPn was only 13. HBPA and HNA were first converted to reactive acyloxyaromatic acid intermediates. Then the DPn was increased by means of reaction‐induced crystallization of oligomers and subsequent solid‐state polymerization via an acid–ester exchange under nonstoichiometric conditions caused by the monocarboxylic acid by‐product. Even though the DPn of PON was not as high, direct polycondensation of HBPA and HNA proceeded successfully with aromatic anhydrides. Copyright © 2004 Society of Chemical Industry     

The STOBBE condensation. X. The cyclisation of (E)-3-methoxycarbonyl-4-(5′-methyl-2′-furyl)-but-3-enoic acid,and (E)−3-methoxycarbonyl-4-(2′-furyl)-pent-3-enoic acid,to Benzofuran Derivatives

The condensation of 5-methyl-furan-2-aldehyde and 2-furyl-methyl ketone with dimethyl succinate using either potassium t-butoxide or sodium hydride as condensing agents, gives predominantly (E)-3-methoxycarbonyl-4-(5′-methyl-2′-furyl)-but-3-enoic acid 1a and (E)-3-methoxy-carbonyl-4-(2′furyl)-pent-3-enoic acid 5 respectively. Their configurations are inferred by cyclisation with sodium acetate in acetic anhydride to the corresponding benzofuran derivatives 2,6 . Alcoholysis of (E)-3-carboxy-4-(5′-methyl-2′-furyl)-but-3-enoic anhydride 3 gives the half-ester 1c which is isomeric with the half-ester 1a . A competing side reaction also gives the self-condensation product of the succinic ester 4 .     

The structure of liquid crystalline aromatic copolyesters prepared from 4-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid

X-ray methods have been used to investigate the structure of liquid crystalline copolyesters prepared from 4-hydroxybenzoic acid (HBA) and 2-hydroxy-6-naphthoic acid (HNA). Fibre diagrams and meridional diffractometer scans have been obtained for melt-spun specimens of five HBA/HNA ratios: $\text{25}\text{75}$, $\text{30}\text{70}$, $\text{50}\text{50}$, $\text{58}\text{42}$ and $\text{75}\text{25}$. The data indicate a high degree of axial orientation. The lateral packing is more irregular but the observation of some equatorial and off-equatorial Bragg reflections indicates the presence of some three-dimensional order. The patterns differ in the number and position of the meridional maxima, and these can be predicted accurately by a point model for aperiodic chains of totally random sequence. The sensitivity of the data to monomer ratio is illustrated by calculations across the range of composition from 100% HBA to 100% HNA.     

Copolymers of Poly(2,5‐benzimidazole) and Poly[2,2′‐(p‐phenylene)‐5,5′‐bibenzimidazole] for High‐Temperature Fuel Cell Applications

Copolymers of poly(2,5‐benzimidazole) (ABPBI) and poly[2,2′‐(p‐phenylene)‐5,5′‐bibenzimidazole] (pPBI) were synthesized for use as fuel cell membranes to take advantage of the properties of both constituents. The composition of the copolymers were controlled by changing the feed ratio of 3,4‐diaminobenzoic acid and terephthalic acid with 3,3′‐diaminobenzidine in the polycondensation reaction. The copolymer membranes showed higher conductivities, better mechanical properties, and larger acid absorbing abilities than commercial poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole] membranes.

     

Synthesis and characterization of new optically active poly(amide‐imide‐urethane) thermoplastic elastomers,derived from 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L‐leucine‐p‐aminobenzoic acid) and PEG‐MDI

A new class of optically active poly(amide‐imide‐urethane) was synthesized via two‐step reactions. In the first step, 4,4′‐methylene‐bis(4‐phenylisocyanate) (MDI) reacts with several poly(ethylene glycols) (PEGs) such as PEG‐400, PEG‐600, PEG‐2000, PEG‐4000, and PEG‐6000 to produce the soft segment parts. On the other hand, 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L ‐leucine‐p‐amidobenzoic acid) (2) was prepared from the reaction of 4,4′‐(hexafluoroisopropylidene)‐N,N′‐bis(phthaloyl‐L ‐leucine) diacid chloride with p‐aminobenzoic acid to produce hard segment part. The chain extension of the above soft segment with the amide‐imide 2 is the second step to give a homologue series of poly(amide‐imide‐urethanes). The resulting polymers with moderate inherent viscosity of 0.29–1.38 dL/g are optically active and thermally stable. All of the above polymers were fully characterized by IR spectroscopy, elemental analyses, and specific rotation. Some structural characterization and physical properties of this new optically active poly(amide‐imide‐urethanes) are reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2288–2294, 2004