The molecular structure and polarizabilities of poly(aryl ether ketone)s

The molecular structure and polarizabilities of poly(aryl ether ketone)s were investigated with quantum chemical calculations, based on the fully optimized structures of model compounds (S₅: ArCOArOArOArCOAr and BS₆: ArOArCOArArCOArOAr) for their chain segments. The results showed that the average dihedral angle between their aromatic rings was in the range of 36°−37° relative to the molecular zig-zag plane. Especially, when a biphenyl group was introduced into the molecular chain of this polymer, its two aromatic rings were distorted by 48.0° to each other. Also, the calculation results of refractive indices for pure crystals obtained by using the structural parameters were in good accordance with those reported in the literature.     

Novel fluorinated poly(aryl ether ketone)s

Two novel fluorinated monomers were prepared and polymerized with biphenols to produce amorphous, thermally stable poly(aryl ether ketone)s. The properties of the fluorinated polymers are compared to those of unfluorinated, amorphous poly(aryl ether ketone)s. The presence of fluorine in the polymers was found to cause a decrease in glass transition temperature and Young's moduli, however, no increase in thermal stability was observed. The fluorinated polymers are soluble in common organic solvents such as chloroform and methylene chloride at room temperature, and also show solubility in solvents containing a ketonic moiety, such as acetone. Evidence of polymer branching through fluorines considered to be unreactive under the polymerization conditions was found. Efforts were made to evaluate the reactivity of fluorine atoms under the polymerization conditions using both molecular modeling and ¹⁹F-NMR to ascertain if such branching could be avoided. © 1995 John Wiley & Sons, Inc.     

Crystal structure and crystallinity of poly(aryl ether biphenyl ether ketone ketone)

The crystal structure of poly(aryl ether biphenyl ether ketone ketone) (PEDEKK) was determined to comprise a two-chain orthorhombic unit cell with dimensions a = 0.778 nm, b = 0.606 nm and c = 2.375 nm by using wide-angle X-ray diffraction (WAXD). According to the orthorhombic system, the 12 reflections of this polymer were indexed. The crystallite size increases with increasing the crystallization temperature. The results of the degree of crystallinity (W_c,x) calculated from WAXD were compatible with those from density (W_c,d) and calorimetry (W_c,h) measurements.     

Relationship between molecular structure and thermal properties of poly(aryl ether ketone)s

Five kinds of poly(aryl ether ketone)s (PAEKs) having para-substituted linear molecular chains were synthesized via nucleophilic substitution reaction of the corresponding difluoro- and dihydroxy-compounds. The glass transition temperature and melting temperature of the PAEKs measured through differential scanning calorimetry in addition to those of other PAEKs reported are approximately proportional to the logarithm of the ratio of the mole fractions of ketone and ether groups in the repeating unit of the PEAKs. On the other hand, this ratio does not affect the crystal structure of the PAEKs.     

Crystallization of poly(aryl ether ketone ketone) copolymers containing terephthalate/isophthalate moieties

In a previous study, we have investigated the structure, crystallization, and morphology of poly(aryl ether ketone ketone), PEKK, copolymers prepared from diphenyl ether (DPE), terephthalic acid (T), and isophthalic acid (I) with T/I ratios from 100/0 to 50/50. These materials were considered as having -DPE-T-DPE-T- (TT) and/or -DPE-T-DPE-I- (TI) “phthalate diads.” In this work, we continue the study of this copolymer series with six different T/I ratios (40/60, 30/70, 20/80, 15/85, 10/90, and 0/100), which are viewed as having TI and/or -DPE-I-DPE-I- (II) “diads.” The I moieties (1,3-linked isomers) were always found to be incorporated in the crystals and acted as “entropy or symmetry” defects that effectively decreased the equilibrium melting temperature T_m^o and the rate of crystallization. However, the retardation of crystallization in PEKK 0/100 (the homopolymer with pure II diads) was significantly less than expected, which was attributed to the segregation of I moieties between the chains leading to a reduction of total entropy in the unit cells. The evidence of segmental segregation in PEKK 0/100 was seen in x-ray diffraction patterns, where several extra reflections were seen that could only be indexed by the published unit cell modified with a larger c-axis dimension (3.048 nm, corresponding to the length of six phenyl residues or 1.524 nm, the length of three phenyl residues). The composition of 15/85 was found to have the lowest value of T_m^o and the slowest crystallization rate. Upon heating, the “II” crystals (T/I from 30/70 to 0/100) exhibited the conventional double-melting behavior rather than the triple-melting behavior as in the “TI” crystals (50/50 to 40/60). No indication of the second polymorph form 2 was found in “II” crystals. © 1994 John Wiley & Sons, Inc.     

聚芳醚酮醚酮酮类聚合物的结晶与多晶型

晶体结构;聚芳醚酮醚酮酮类聚合物的结晶与多晶型     

Fluorenyl-containing sulfonated poly(aryl ether ether ketone ketone)s (SPFEEKK) for fuel cell applications

A series of fluorenyl-containing sulfonated poly(aryl ether ether ketone ketone)s (SPFEEKK) were synthesized via aromatic nucleophilic substitution polymerization. The sulfonation content (SC) was controlled by the feed ratios of sulfonated and nonsulfonated monomers. Flexible and strong membranes in the sulfonic acid form were obtained from cast membranes in the sodium salt forms by treatment with acid. The thermal properties, water uptake, swelling ratio, water state, oxidative stability, proton conductivity and methanol permeability were investigated. All the polymers had proton conductivities greater than 1 × 10⁻² S/cm at room temperature, and the conductivity values of m-SPFEEKK-80 and p-SPFEEKK-80 were up to 1.86 × 10⁻¹ and 1.78 × 10⁻¹ S/cm at 100 °C. This series of polymers also possessed good dimensional stability in water and low methanol crossover.     

Isothermal melt and cold crystallization kinetics of poly(aryl ether ketone ether ketone ketone)

The isothermal melt and cold crystallization kinetics of poly(aryl ether ketone ether ketone ketone) are investigated by differential scanning calorimetry over two temperature regions. The Avrami equation describes the primary stage of isothermal crystallization kinetics with the exponent n ≈ 2 for both melt and cold crystallization. With the Hoffman–Weeks method, the equilibrium melting point is estimated to be 406 °C. From the spherulitic growth equation proposed by Hoffman and Lauritzen, the nucleation parameter (K_g) of the isothermal melt and cold crystallization is estimated. In addition, the K_g value of the isothermal melt crystallization is compared to those of the other poly(aryl ether ketone)s. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1992–1997, 2000     

Sulfonated poly(aryl ether ether ketone ketone)s containing fluorinated moieties as proton exchange membrane materials

A series of sulfonated poly(aryl ether ether ketone ketone)s statistical copolymers with high molecular weights were synthesized via an aromatic nucleophilic substitution polymerization. The sulfonation content (SC), defined as the number of sulfonic acid groups contained in an average repeat unit, could be controlled by the feed ratios of monomers. Flexible and strong membranes in sodium sulfonate form could be prepared by the solution casting method, and readily transformed to their proton forms by treating them in 2 N sulfuric acid. The polymers showed high T_gs, which increased with an increase in SC. Membranes prepared from the present sulfonated poly(ether ether ketone ketone) copolymers containing the hexafluoroisopropylidene moiety (SPEEKK‐6F) and copolymers containing the pendant 3,5‐ditrifluoromethylphenyl moiety (SPEEKK‐6FP) had lower water uptakes and lower swelling ratios in comparison with previously prepared copolymers containing 6F units. All of the polymers possessed proton conductivities higher than 1 × 10^?2 S/cm at room temperature, and proton conductivity values of several polymers were comparable to that of Nafion at high relative humidity. Their thermal stability, oxidative stability, and mechanical properties were also evaluated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2299–2310, 2006     

Synthesis and characterization of the B3-monomer and hyperbranched poly(aryl ether ketone)s

Hyperbranched poly(aryl ether ketone)s were prepared by polymerization of hydroquinone (A₂) and 1,3,5-tris[4-(4-fluorobenzoyl)phenoxy]benzene (B₃). The gelation of hyperbranched poly(aryl ether ketone)s was effectively avoided. Hydroxyl-term inated (HPAEK-OH) and fluoro-terminated (HPAEK-F) hyperbranched poly(aryl ether ketone)s were prepared by using different A₂/B₃ mass ratio. The structure of the B₃ monomer was confirmed by MS, ¹H NMR/IR. The glass transition temperatures of the HPAEK-F and HPAEK-OH are 114°C and 162°C respectively. Thermal stability of HPAEK-F is higher than HPAEK-OH. __________ Translated from Acta Scientianum Naturalium Universitatis Jilinensis, 2005, 5 (in Chinese)     

Thermal behavior and phase behavior in blends of liquid crystalline poly(aryl ether ketone) and poly(aryl ether ether ketone) containing thioether units

Thermal behavior and phase behavior in blends of liquid crystalline poly(aryl ether ketone) with lateral methoxy groups (M-PAEK) and poly(aryl ether ether ketone) containing thioether units (S-PEEK) have been investigated by differential scanning calorimetry (DSC) and polarized light microscopy (PLM) techniques. The results indicate that the composition of the blends has great effect on the phase behavior and morphology. Thin films of pure M-PAEK and S-PEEK crystallized from the melts exhibit typical mosaic and spherulitic structures, respectively. For the blends with higher M-PAEK contents (> 50%), an unusual ring-banded spherulite with structural discontinuity is formed. The bright core and rings of the ring-banded spherulites under PLM are composed of M-PAEK phase, while the dark rings consist mainly of S-PEEK phase. For the 50:50 M-PAEK/S-PEEK blend, the ring-banded spherulites and S-PEEK spherulites coexist, which implies that a partial phase separation between the two components takes place in the melting state. In S-PEEK-rich blends, a volume-filled spherulite is produced. In addition, the effect of isothermal crystallization temperature on the phase behavior, especially the ring-banded spherulite formation in the blends, is discussed.     

Dielectric and dynamic mechanical relaxation studies on poly(aryl ether ketone)s

The relaxation behavior of four amorphous poly(aryl ether ketone)s was investigated using dielectric relaxation spectroscopy and dynamic mechanical analysis. The temperature dependence of the relaxation times of the glass transition process and the cooperative nature of this process were unaffected by changes in polymer structure. The temperature location of the loss peaks for all polymers progressed smoothly between the low frequency of the mechanical measurements and the higher frequencies of the dielectric probe. Differences were observed in mechanical activation energy and dielectric relaxation strength for one polymer which contained a significant concentration of meta linkages, compared with the para-linked polymers, while relaxation broadness was generally greater in the dynamic mechanical mode. Changes in chemical structure had little effect on the shape, intensity, and location of the β-relaxation peak, the main observation being that the Arrhenius activation energy measured by dynamic mechanical analysis was significantly higher than that calculated from the dielectric data. The dielectric β-relaxation was sensitive to absorbed moisture. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 851–859, 1998     

聚芳醚酮模型化合物分子结构与分子极化的研究

本文合成了一系列的聚芳醚酮模型化合物, 研究了它们在硫酸及氯仿(或氯仿加二甲亚砜)中的分子结构变化, 实验结果表明, 硫酸使其分子产生明显极化。在UV谱中, 波长在400nm左右处出现新的吸收峰, ^1^3C NMR谱中, 羰基碳弛豫时间缩短, 化学位移增加而与羰基相连的季碳弛豫时间与化学位移均减小。计算得到芳环平均两面角36°~39°, 据此计算了不同极化模型的电荷运移, 提出极化机理为桥键受硫酸质子化及偶极作用使芳环电荷离域。     

含间苯连接的聚醚醚酮酮的等温结晶过程和形态结构

用透射电子显微镜和电子衍射方法研究了含间苯连接的聚醚醚酮酮（PEEKmK）溶液浇铸薄膜的等温结晶过程和形态结构．结果表明，PEEKmK无论从玻璃态结晶还是从熔体结晶均能形成2种不同取向的结晶形态结构，即平放片晶和侧放片晶；前者c轴垂直于膜平面，后者c轴平行于膜平面．其结晶发展过程为先形成平放单晶状片晶，随着时间的增长，在单晶上开始生长侧放片晶，逐渐发展形成球晶，最终形成2种不同取向的单晶和球晶共存的结晶形态结构．     

Isomorphic behavior of poly(aryl ether ketone) blends

Blends of various poly(aryl ether ketones) have been found to exhibit a range of miscibility and isomorphic behavior. This range is dependent on molecular weight; however, for poly(aryl ether ketones) with number-average molecular weight of 20,000, this range is about ±25% difference in ketone content. All miscible blends exhibit isomorphism, and all immiscible blends exhibit no evidence of isomorphism. The dependence of the glass transition temperature T_g versus composition exhibits a minimum deviation from linearity whereas the melting temperature T_m versus composition exhibits a pronounced maximum deviation from linear behavior. The crystalline melting point versus composition for isomorphic blends is considerably different than for random copolymers with isomorphic units. Homopolymers and random copolymers exhibit a melting point that is a linear function of ketone content (increasing ketone content increases T_m). For blends, the melting point is essentially the same as that of the higher melting constituent until high levels of the lower melting constituent are present. The observed melting point versus composition behavior will be interpreted using classical theory to calculate the components of the liquid and crystalline phase compositions. As a miscible blend is cooled from the melt, essentially pure component of the highest melting point crystallizes out of solution, as predicted by calculated solid-liquid phase diagrams. This occurs until the crystallization is complete owing to spherulitic impingement. At high concentrations of the lower melting constituent, lower melting points will be observed because the highest melting constituent will be depleted before the crystallization is complete. In many miscible blends involving addition of an amorphous polymer to a crystalline polymer, the degree of crystallinity of the crystalline polymer has been shown to increase. On the basis of evidence presented here, it is hypothesized that dilution by a miscible, amorphous polymer allows for a higher level of crystallinity.     

Stress-enhanced transport of toluene in poly aryl ether ether ketone (PEEK)

The transport of fluids in the semicrystalline polymer, poly(aryl ether ether ketone) (PEEK), was investigated. Both solubility and rate of penetration of toluene into PEEK are markedly increased by the application of an external stress. The induction period (i.e., the time for the sorption to begin) is a function of applied stress as well as temperature and crystallinity. At 22°C in 29% crystalline PEEK the induction period was reduced from more than 2000 h to approximately 10 h whereas the solubility of toluene was increased from 9 to 44 wt % upon the application of an external tensile stress of 30 MPa. A critical stress (i.e., a stress value below which the stress-enhanced effects are not observed) was determined. The critical stress is a strong function of crystallinity and temperature. © 1996 John Wiley & Sons, Inc.     

稀土催化异戊二烯-马来酸酐交替共聚

研究了含氟基团的引入对聚醚醚酮（PEEK）的介电常数、溶解性、结晶性和力学性能等的影响，结果表明，这种含氟聚芳醚酮在保持PEEK良好机械性能的条件下，介电常数达到2．7，且频率依赖性小，成膜性能好，成本比相应的含氟PI低5－10倍，有望成为一种极有实用价值的电子封装材料，同时利用合成的含氢氟单体合成了一系列不同－CF3取代基含量的聚芳醚酮共聚物，研究了聚芳醚酮共聚物的介电常数与聚合物结构单元中－CF3取代基含量的关系，结果表明，聚芳醚酮共聚物的介电常数的介电常数随聚合结构单元中－CF3取代基含量的增加而线性降低。     

含氟聚芳醚酮的合成与性能研究

研究了含氟基团的引入对聚醚醚酮(PEEK)的介电常数、溶解性、结晶性和力学性能等的影响.结果表明,这种含氟聚芳醚酮在保持PEEK良好机械性能的条件下,介电常数达到2.7,且频率依赖性小,成膜性能好,成本比相应的含氟PI低5～10倍,有望成为一种极有实用价值的电子封装材料.同时利用合成的含氟单体合成了一系列不同-CF₃取代基含量的聚芳醚酮共聚物,研究了聚芳醚酮共聚物的介电常数与聚合物结构单元中-CF₃取代基含量的关系.结果表明,聚芳醚酮共聚物的介电常数随聚合物结构单元中-CF₃取代基含量的增加而线性降低.     

Structure‐controlled synthesis of novel soluble and thermally stable poly (aryl ether nitrile ether ketone ketone)/poly (aryl ether nitrile ether ketone biphenyl ketone) copolymers by electrophilic polycondensation

One new synthesis route was first designed to synthesize the biphenyl acid chloride (BPACl), and then a series of novel poly (aryl ether nitrile ether ketone ketone) (PENEKK)/poly (aryl ether nitrile ether ketone biphenyl ketone) (PENEKBK) copolymers with different controlled structure compositions were synthesized by electrophilic polycondensation and varying the molar ratio of BPACl to terephthaloyl chloride (TPC). The obtained PENEKK/PENEKBK copolymers were characterized by different physical and chemical techniques. The results showed, the copolymers with 10–50% molar contents of biphenyl moities exhibited good thermal properties with glass transition temperatures (T_gs) of 184–196°C, decomposition temperatures (T_ds) of 498–515°C, and good solubility in organic solvents (N‐Methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide (DMF), and DMSO), indicating that they would have good potential for solvent processing. The thin films of the polymers had tensile strengths of 93.6–101.5 MPa, Young's moduli of 3.03–3.32 GPa, elongations at break of 9–14%, indicating they were strong materials. The densities of the obtained polymers were 1.31–1.40 g/cm^?3, which were far lower than those of some main inorganic materials (such as Fe, nearly 7.8 g/cm^?3), indicating that they would have possible potential for substituting some inorganic materials used as high temperature materials in some areas due to the merits of lightweight. Thus, the copolymers with 10–50% molar contents of biphenyl moities were promising polymer materials. Copyright © 2010 John Wiley & Sons, Ltd.