Synthesis,thermal and radiation sensitivities of halogen-containing decamethylene-spacered aromatic polyesters

A series of halogen-containing aromatic polyesters with decamethylene-spacer groups was synthesized by the solution polymerization from 4,4′-dicarboxyl-1,10-diphenoxy-decane and bisphenol A. Incorporation of fluorine atoms in the bisphenol A units in the polymer backbone enhanced the solubility of the polyesters in various organic solvents, as did the substitution of chlorine and bromine on the aromatic rings of the bisphenol A, ortho to the ester linkages. The effect of the halogen substituents on the thermal and radiation sensitivities of the polyesters has been investigated. The inherent viscosities of THF solutions at 30°C ranged from 0.25 to 0.63 dL/g. The number average (6,000∼31,000) and weight average molecular weights (12,000∼48,000) were measured by gel permeation chromatogrpahy, resulting in polydispersity indices of M₂/M_n=1.6∼2.0. The chemical structures of the polyesters were characterized by means of IR spectroscopy, ¹H NMR and ¹³C NMR spectroscopies and elemental analyses. All the results were in good agreement with the expected formula. Comparison of ¹³C NMR spectra of the polymers aided in the assignments of the structures. Only the unsubstituted polyester derived from bisphenol A was found to be semicrystalline by X-ray diffraction and DSC measurements, with a crystalline melting temperature of 160°C. The glass transition temperatures of the polyesters was found to be dependent on the size of the halogen substituent on the repeating units, and ranged from 77 to 140°C. The thermal stabilities of the polyesters showed a dependence on the nature of the halogen substituent, as did the high energy radiation sensitivites of the polymers, as assessed by the yields of radicals at 77 K. © 1998 John Wiley & Sons, Ltd.     

界面缩聚法制备间苯二甲酰双酚酸酯聚芳酯

以四丁基氯化铵为相转移催化剂,双酚酸甲酯或双酚酸乙酯与间苯二甲酰氯界面缩聚,合成得到了侧链含酯基的聚芳酯.在吡啶、三乙胺、碳酸氢钠、氢氧化钠中选择合适的催化剂,既可以发生聚合反应又不会使双酚酸酯的酯基发生水解.聚合反应在7种溶剂中进行,通过探讨聚合反应机理以解释溶剂对聚合反应产率以及聚合物特性黏数的影响.以二氯甲烷为溶剂,在优化的聚合条件下较高产率地得到了高特性黏数的聚合物.DSC及TGA分析表明,间苯二甲酰双酚酸酯类聚芳酯具有比间苯二甲酰双酚酸好的热稳定性,热分解温度可从200℃提高到300℃.     

Effects of ionizing radiation on linear aromatic polyesters

The influence of chemical structure on the response of aromatic polyesters to high-energy ionizing radiation was studied. Systematic variations of polymers related to poly(ethylene terephthalate) were subjected to γ radiation, and the competitive chain scission and crosslinking reactions were determined by measuring changes in intrinsic viscosity and molecular weights. It was found that an increase in the paraffinic glycol segment of polyterephthalates facilitated crosslinking, while the protective nature of aromatic groups was demonstrated by modifying the dibasic acid segments. The influence of substituents on the terephthalate moiety was mixed: electronegative groups led to chain scission (as evidenced by decreased viscosities), but electropositive substituents exerted a stabilizing effect on polymer viscosity. In almost all cases, number-average molecular weights were decreased by exposure to γ radiation, regardless of viscosity behavior. Crystalline melting temperatures of the polymers generally were decreased by the combined radiation effects of chain scission and crosslinking.     

Synthesis and characterization of new polyesters with enhanced phosphorus content

New polyesters were prepared from several aromatic phosphonic dichlorides and a diolic monomer bearing a cyclic bulky group containing phosphorus. From kinetic investigation, the rates of polycondensation in melt were calculated and compared with those of the reaction between aromatic diols and phosphonic dichloride. Polyesters were analytically, spectral and thermally characterized and effect of structure on optical properties was investigated.     

Mechanism of Catalyst Action in Interfacial Polycondensation of Chlorobisphenol and Isophthaloyl Chloride

The mechanism of action of quaternary ammonium salt catalysts in the synthesis of aromatic polyesters was investigated. The possibility of formation of compounds of these salts and bisphenols and their extraction in the form of an ion pair into the organic phase was investigated. The structure of the compounds obtained was determined.     

New polymer syntheses. 60. Thermostable polymers of 2-(hydroxyaryl)benzoxazole-5-carboxylic acids

Tristrimethylsilyl-3-amino-4-hydroxybenzoic acid was condensed with various aromatic acetoxy carboxylic acid chlorides in Marlotherms-S® at 20–350°C. Under these conditions formation of an amide group, ring closure to benzoxazole groups and polycondensation occur step by step in a “one-pot procedure”. The crude polyesters were hydrolyzed to yield pure 2-(hydroxyaryl) benzoxazole-5-carboxylic acids which were acetylated and polycondensed. The pure polyesters obtained in this way were characterized by viscosity and DSC measurements, WAXS-powder patterns, and thermogravimetric analyses. The polyester of 2-(4-hydrophenyl) benzoxazole-5-carboxylic acid has a degree of crystallinity > 90% and a short term in thermostability in air up to 500°C.     

Thermal degradation of polymers with phenylene units in the chain. III. Polyarylates

The thermal decomposition of three aromatic polyesters was studied in vacuo. The degradation products were analyzed by mass spectroscopy, infrared spectroscopy, and elemental analysis. Breakdown mechanisms are proposed. Primary cleavage of the ester linkages appears to take place either between the carbonyl and the oxygen or between the oxygen and the ring, yielding carbon monoxide and carbon dioxide in varying ratios. Another major decomposition product is a sublimate which seems to consist mainly of the phenolic component of the polyester. A polyester with a 2,2-propylene linkage showed, as expected, early loss of methane. A pendent pentyloxy chain in one of the polymers is removed almost completely below 350°C with formation of alkanes and alkenes. Lack of oxygen in the fragments indicates that the main cleavage must occur between the ether oxygen and the aliphatic chain or with in the aliphatic chain.     

Phenothiaphosphine-containing polyamides and polyesters

Phosphorus-containing polyamides and polyesters, which had tricyclic fused rings (phenothia-phosphine rings) in the main chain, were prepared and the properties of the resulting polymers were examined. These polymers were obtained at highly reduced viscosities in satisfactory yields by the polycondensation of 2,8-dichloroformyl-10-phenylphenothiaphosphine 5,5,10-trioxide with aromatic diamines or bisphenols. The polyamides and polyesters were soluble in polar aprotic solvents such as dimethylacetamide and N-methyl-2-pyrrolidone; the polyesters were also soluble in chloroform. The polymers exhibited good heat resistance. The phenothiaphosphine-containing polyamides and polyesters self-extinguished immediately when flame was removed and were highly flame-resistant. The polyester obtained from bisphenol A showed a limiting oxygen index value of 43.5.     

Direct synthesis of aromatic polyesters by use of a sulfonium salt derived from tosyl chloride and N-methylimidazole

A sulfonium salt derived from tosyl chloride and N-methylimidazole was successfully used as an effective condensing agent for the preparation of high-molecular-weight aromatic polyesters by the direct polycondensation of aromatic dicarboxylic acids and bisphenols. Conditions for the formation of the sulfonium salt and of the reaction of the salt with dicarboxylic acids favorable for the polycondensation were examined. Thermal property of a polymer was investigated in terms of random sequences of monomer in the polymer backbone. Preparation of a polyamide and a polyesteramide was attempted with limited success.     

Aromatic components in copolyesters: Model structures help to understand biodegradability

Copolyesters build of aliphatic and aromatic components have been shown to be degraded by microorganisms in a certain range of composition. While aliphatic polyesters of diol and dicarbonic acid often are hydrolyzed e.g. by lipases, pure aromatic polyesters like polyethylene terephthalate are not biodegradable. To understand the degradation mechanism of complex aliphatic/aromatic copolymers, we performed degradation experiments with different enzymatic systems and also especially screened highly active microorganisms. Several polymers and monomeric esters representing distinct structure elements within the polymer-chain have been synthesized. These model structures were investigated in terms to understand the correlation of the stereo selectivity of the tested enzymes and the biodegradability of the polymer structure.     

Structure and mesophase of a new series of aromatic polyesters

A new series of aromatic polyesters in which the polymethylene flexible spacers are connected with the rigid main chain containing benzene ring were prepared by interfacial polycondensation. The polymers were characterized by hotstage polarized microscopy, differential scanning calorimetry, wide-angle X-ray diffraction and Fourier-transform infrared spectroscopy. The structure and properties of polyesters were investigated. The results showed that the textures of the thermotropic liquid-crystalline polyesters are smectic and/or nematic. The dependence of melting point, clearing point and transition enthalpy of polyesters on length of the alkylene group revealed a regular zig-zag trend. The thermal analysis of polyesters revealed that the clearing transition is an equilibrium process, so the entropy of this transition may be taken as an indication of the degree of the order in mesomorphic state presented in the system. Furthermore, the thermal history of polymer had a significant effect on its thermal behavior. The regular arrangement of methylene segments changed when polymer melted from the crystal state to the liquid-crystalline state. The research also implicated that the conformational change of the methylene flexible spacer was one of the reasons for this thermal effect.     

结晶性芳香聚酯高压结晶行为研究进展

运用高压极限手段研究聚合物的结构、形态和性能是20世纪60年代以来兴起的一项聚合物前沿课题。本文主要结合作者自己的研究工作，重点叙述聚对苯二甲酸乙二醇酯(PET)的高压结晶行为研究，包括温度、压力、时间及分子量对PET高压结晶行为的影响，高压结晶PET的形态。以及对PET伸直链晶体结晶机理的探讨，同时简要介绍了对其它结晶性芳香聚酯诸如聚对苯二甲酸丁二醇酯(PBT)及聚对萘二甲酸乙二醇酯(PEN)的高压结晶行为研究，反映了该领域的研究概况和最新进展。并对今后的研究提出了展望。     

A series of furan‐aromatic polyesters synthesized via direct esterification method based on renewable resources

A series of furan‐aromatic polyesters were successfully synthesized via direct esterification method starting from 2,5‐furandicarboxylic acid, ethylene glycol, 1,3‐propanediol, 1,4‐butanediol, 1,6‐hexanediol, and 1,8‐octanediol and characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (¹H NMR), X‐ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), tensile tests, and so on. The preliminary evidence clearly showed that direct esterification method was rewarding and worthy to synthesize these furan‐aromatic polyesters. The densities of furan‐aromatic polyesters were ranging from 1.19 to 1.38 kg/m³. The FTIR and ¹H NMR confirmed their expected structures in detail. The results of XRD showed that these furan‐aromatic polyesters were crystalline polyesters. The results of DSC, TGA, DMA, and tensile tests showed that they behaved as thermoplastic polyester, had satisfactory thermal and mechanical properties, and their thermal stabilities were quite similar to that of corresponding benzene‐aromatic polyesters. The results of contact angle measurement showed that they were hydrophilic. The properties above showed that furan‐aromatic polyesters based on renewable resources could be a viable alternative to their successful petrochemical benzene‐aromatic counterpart. Furthermore, they could be used as biopolymer materials according their satisfactory thermal and mechanical properties and hydrophilicity in the future. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

含有烷基取代基的热致液晶性全芳香共聚酯的合成

<正> 聚对苯二甲酸对苯二酚酯具有类似于聚对苯二甲酰对苯二胺的刚性棒状分子结构,其分子的相关长度甚至还大大超过后者,这就使得有可能由此聚合物纺制出高强度的纤维。遗憾的是,聚对苯二甲酸对苯二酚酯的熔点太高,又尚未找到能使它溶解从而制     

Gamma irradiation of polyester films

Irradiation in air of several thermoplastic aromatic polyesters was carried out in order to investigate changes in characteristic properties. Polymers are irradiated at high doses, until 1 MGy, and no drastic changes seem to emerge. Dielectric and resistance measurements are carried out in order to evaluate changes in electrical insulation property; moreover, nanoholes dimensions, analyzed by positron spectroscopy, are measured in pristine and irradiated polyesters. The study shows good durability of this kind of polyesters, due to the aromatic rings able to stabilize the polymeric chains towards ionizing radiations and able to preserve the original structural, electrical and permeability properties.     

Photolysis of polyesters: Poly(propylene-1,2-maleate) and poly(propylene-1,2-ortho-phthalate)

A spectroscopic study of the photo-oxidation of poly(propylene-1,2-maleate), poly(propylene-1,2-o-phthalate) and poly(propylene-1,2-maleate-o-phthalate) under 280–480 nm radiation was investigated in detail. Results obtained indicate that, during photolysis of these polyesters, the primary photoreactions involve excitation of conjugated structures: carbonyl groups (in ester groups)—double bonds or carbonyl groups-phenylene rings. The secondary reactions occur by complicated mechanisms resulting in oxidation, scission, radical termination and cross-linking of structures present in the photolysed polyesters. Light of wavelength 280–480 nm causes deterioration in the polyesters in the early stages of irradiation. Singlet oxygen does not react with these polyesters even during long periods of exposure. Photo-oxidation mechanism occurs by free radical mechanism.     

THE GAS TRANSPORT BEHAVIOR IN AROMATIC POLYESTER MEMBRANES

Six aromatic polyesters were prepared for gas separation membranes, and their per-meation properties for hydrogen, oxygen, nitrogen, carbon dioxide, and methane weremeasured at 30℃ and 1 atmosphere by low pressure manometric method. The cor-relation between the gas transport behavior and molecular structure of aromatic polyestermembrane is discussed. These data are interpreted qualitatively in terms of the calculatedpacking density, gas-polymer interaction, concentration of aryl bromine on backbone, andeffect of silane group on main chain of polymer.     

Isothermal melt-crystallization and melting behavior for three linear aromatic polyesters

Isothermal crystallization and subsequent melting behavior for three different types of linear aromatic polyester, namely poly(ethylene terephthalate) (PET), poly(trimethylene terephthalate) (PTT), and poly(butylene terephthalate) (PBT), were investigated (with an emphasis on PTT in comparison with PET and PBT). These polyesters were different in the number of methylene groups (i.e. 2, 3, and 4 for PET, PTT, and PBT, respectively). Isothermal crystallization studies were carried out in a differential scanning calorimeter (DSC) over the crystallization temperature range of 182-208 °C. The wide-angle X-ray diffraction (WAXD) technique was used to obtain information about crystal modification and apparent degree of crystallinity. The kinetics of the crystallization process was assessed by a direct fitting of the experimental data to the Avrami, Tobin, and Malkin macrokinetic models. It was found that the crystallization rates of these polyesters were in the following order: PBT>PTT>PET, and the melting of these polyesters exhibited multiple-melting phenomenon. Lastly, the equilibrium melting temperature for these polyesters was estimated based on the linear and non-linear Hoffman-Weeks (LHW and NLHW) extrapolative methods.     

脂肪族聚酯及共聚酯的生物降解性研究

以酯交换法或直接缩聚法合成了一系列脂肪族聚酯，经二异氰酸酯(HDI)扩链得到含氨酯键的聚酯及共聚酯，用DSC、X射线衍射等分析表征了聚酯及共聚物的结构和性能。用土埋试验、CO2释放试验和黑曲霉降解试验着重研究了这些聚合物的生物降解性，详细讨论了聚酯结构、组成及聚酯分子量对生物降解性的影响。     

Interfacial Polycondensation in Aqueous and Non-Aqueous Systems

Abstract

Interfacial polycondensation in aqueous and non-aqueous systems has been investigated in order to synthesize various polyamides having functional groups. Rigid aromatic polyamides having pyridine moieties (PPy) were synthesized by interfacial polycondensation using an aqueous system and the solution properties of PPy in concentrated sulfuric acid were investigated in terms of solution viscosity and lyotropic behavior. Interfacial polycondensation in a non-aqueous system using two immiscible solvents was found to be useful for the synthesis of aromatic polyesters and copolyesters.