Preparation and characterization of carbon membranes made from poly(phthalazinone ether sulfone ketone)

Carbon membranes were prepared from a novel polymeric precursor of poly(phthalazinone ether sulfone ketone) (PPESK), of which the changes of microstructure and chemical compositions during pyrolysis from 500 °C to 950 °C were monitored by thermal gravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. It has been found that the weight loss of the PPESK precursor up to 800 °C is about 43.0 wt%. After the heat treatment, the typical chemical structure of the PPESK precursor disappears, at the same time a graphite-like structure with more aromatic rings is formed. The interlayer spacing (i.e., d value) decreases from 0.471 nm to 0.365 nm as the pyrolysis temperature increases. The gas permeation performance of carbon membranes has been tested using pure single gases including H₂, CO₂, O₂ and N₂. For the carbon membrane obtained by carbonizing the PPESK precursor at 800 °C, the maximum ideal permselectivities for H₂/N₂, CO₂/N₂ and O₂/N₂ gas pairs could reach 278.5, 213.8 and 27.5, respectively.     

Application of poly(phthalazinone ether sulfone ketone)s to gas membrane separation

A series of poly(phthalazinone ether sulfone ketone) (PPESK) copolymers containing different component ratios of bis(4‐fluorodiphenyl) ketone and bis(4‐chlorodiphenyl)sulfone with respect to a certain amount of 4‐(4‐hydroxyphenyl)‐2,3‐phthalazin‐1‐one were synthesized by polycondensation. Glass transition temperatures of these polymers were adjusted from 263°C to 305°C by changing the ratios of reactants. Gas permeability and selectivity of the dense membranes of the polymers for three kinds of gases (CO₂, O₂, and N₂) were determined at different temperatures. The result indicated that the membrane of PPESK (S/K = 1/1, mol ratio) had an excellent gas separation property. Permeability of the polymer membranes for CO₂, O₂, and N₂ was P = 4.121 barrier, P = 0.674 barrier, and P = 0.0891 barrier, respectively. Separation factors of α and α were 7.6 and 46, respectively. New material was made into a composite membrane with silicone rubber for blocking up leaks and defects on the surface of its nonsymmetrical membrane. As a result of the test, permeability of the composite membrane was J = 7.2 × 10⁻⁶ cm³ (STP) cm⁻² S⁻¹ cm⁻¹ Hg and J = 0.99 × 10⁻⁶ cm³ (STP) cm⁻² S⁻¹ cm⁻¹ Hg, whereas the α was still higher than 7. These showed that PPESKs had a bright prospect as the potential membrane material for high‐temperature gas separation. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2385–2390, 1999     

聚醚砜/磺化聚醚醚酮共混膜的制备和性能

采用流延法制备了聚醚砜(PES)含量不同的PES/磺化聚醚醚酮(SPEEK)共混膜。PES与SPEEK具有良好的相容性。所制备PES/SPEEK共混膜的含水率、溶胀度和甲醇透过系数均随PES含量的增加而降低。虽然共混膜的质子传导性能有所降低.但阻醇性能和溶胀性能提高,这说明PES/SPEEK共混膜是一种很好的直接甲醇燃料电池用固体高分子电解质膜材料。     

Synthesis and characterization of sulfonated poly(phthalazinone ether sulfone ketone) for ultrafiltration and nanofiltration membranes

Modification of poly(phthalazinone ether sulfone ketone) (PPESK) by sulfonation with concentrated or fuming sulfuric acid as sulfonation agents was carried out to prepare membrane materials with increased hydrophilicity and potentially increased fouling resistance. Sulfonated PPESK (SPPESK) copolymers, with a degree of sulfonation ranging from 10–300%, were prepared and characterized. Factors affecting the sulfonation reaction were studied, and reaction conditions for the preparation of SPPESK with different degrees of sulfonation were determined. Compared with the properties of PPESK, the hydrophilicity of SPPESK was increased, as shown by a reduced contact angle with water. The glass transition temperature was increased from 278°C (PPESK) to a maximum of 323°C for the highly sulfonated derivative, due to the strong polarity of  SO₃H and hydrogen bonding. Ultrafiltration membranes prepared with PPESK and SPPESK were compared. For a SPPESK asymmetric membrane, the PEG12000 rejection was 98% and the water flux was 876 kg · m⁻² · h⁻¹. SPPESK/PPESK composite nanofiltration membranes were also prepared and were shown to have short‐term operational stability up to 120°C. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1685–1692, 2001     

低截留分子质量新型聚芳醚腈酮超滤膜的研制

以新型聚芳醚腈酮为膜材料 ,以N -甲基 - 2 -吡咯烷酮 (NMP)为溶剂 ,研究了聚合物浓度、添加剂种类及含量、凝胶浴温度等对超滤膜性能的影响。结果表明 ,聚合物质量分数以 1 2 %～ 1 3 %为合适的制膜浓度 ,以聚乙二醇PEG - 4 0 0为添加剂时获得了高截留率和高水通量的超滤膜。随着凝胶浴温度的升高 ,水通量明显增大 ,而截留率有所下降 ,而共聚物的浓度增加则有相反的效果。制得的超滤膜具有较低的截留分子量 (PEG- 2 0 0 0 ) ,将制得的超滤膜用于达旦黄、黄X-G等染料的分离 ,截留率均达 90 %以上     

Temperature-dependent gas transport performance of vertically aligned carbon nanotube/parylene composite membranes

A novel composite membrane consisting of vertically aligned carbon nanotubes (CNTs) and parylene was successfully fabricated. Seamless filling of the spaces in CNT forests with parylene was achieved by a low-pressure chemical vapor deposition (CVD) technique and followed with the Ar/O₂ plasma etching to expose CNT tips. Transport properties of various gases through the CNT/parylene membranes were explored. And gas permeances were independent on feed pressure in accordance with the Knudsen model, but the permeance values were over 60 times higher than that predicted by the Knudsen diffusion kinetics, which was attributed to specular momentum reflection inside smooth CNT pores. Gas permeances and enhancement factors over the Knudsen model firstly increased and then decreased with rising temperature, which confirmed the existence of non-Knudsen transport. And surface adsorption diffusion could affect the gas permeance at relatively low temperature. The gas permeance of the CNT/parylene composite membrane could be improved by optimizing operating temperature.     

杂萘联苯聚芳醚酮超滤膜的铸膜液配方研究

为了考察不同铸膜液配方对相转化法制备杂萘联苯聚芳醚酮(PPEK)非对称超滤膜的影响,按照固定1种组分质量分数,改变另外2种组分比例的方法,对铸膜液黏度、凝胶速度及膜结构和性能的变化规律进行了研究。结果表明,聚合物质量分数是决定黏度的主要因素,而铸膜液黏度和添加剂的亲水性对凝胶速度影响很大;铸膜液黏度和凝胶速度可以较好地解释膜结构和性能的变化规律。     

Controlled synthesis of high performance carbon/zeolite T composite membrane materials for gas separation

A simple approach has been developed to synthesize the carbon/zeolite T composite membrane materials with the high gas separation performance. The precursors of the composite membrane are composed of polyimide matrix and dispersed zeolite T particles. The composite membranes prepared by pyrolysis at 973 K show excellent gas (H₂, CO₂, O₂, N₂, and CH₄) permeability and selectivity (O₂/N₂, CO₂/CH₄) for both single gas and mixed-gas. The gas separation performance of the composite membranes can be controlled in a wide range by only changing the zeolite T particle size. The maximum selectivity of O₂ over N₂ (21/79 mol%) for the composite membranes with the least zeolite T particle (0.5 μm) is 15 with an O₂ permeability of 347 Barrers (1 Barrer = 7.5 × 10⁻¹⁸ m² s⁻¹ Pa⁻¹) and the selectivity of CO₂ over CH₄ (50/50 mol%) reaches a value of 179 with a CO₂ permeability of 1532 Barrers. It is believed that the increase of gas permeability is attributed to the ordered microchannels in the zeolite and the interfacial gaps formed between zeolite and carbon matrix in the composite membranes. And the gas selectivity is tuned by the size of interfacial gaps which are varied with the zeolite particle size. This technique will provide a simple and convenient route to efficiently improve the trade-off relationship between the permeability and the selectivity and enable the construction of carbon-based composite materials with novel functionalities in membrane science.     

Synthesis, characterization and optical properties of cross-linkable poly(phthalazinone ether ketone sulfone)

Cross-linkable poly(phthalazinone ether ketone sulfone) bearing tetrafluorostyrene groups (PPEKS-FSt) has been prepared by copolycondensation reaction for optical waveguide applications. The resulting amorphous polymer exhibits good solubility in some common polar organic solvents (e.g., N,N′-dimethylacetamide, N-methyl-2-pyrrolidinone, chloroform) at room temperature, and can be easily spin-coated into thin films with good optical quality. The glass transition temperature (T_g) and the temperature of 1% weight loss (1% T_d) are 261 °C and 494 °C, respectively, which could be further increased by 31 °C and 14 °C upon thermal cross-linking. The cross-linked polymer thin films exhibit high refractive index (∼1.65, TE mode), high thermo-optic coefficient value (dn/dT) (−1.455 × 10⁻⁴/°C, TE mode), low optical loss (less than 0.24 dB/cm at 1310 nm) and relatively low birefringence (∼0.007).     

Hollow fiber microfiltration membranes from poly(ether ether ketone) (PEEK)

A procedure for obtaining high performance large internal diameter (ID; >1 mm) hollow fiber microfiltration membranes from poly(ether ether ketone) (PEEK) is presented. A simple mixture of isomers of diphenylphthalate is a good solvent for employing the thermal‐phase inversion process to obtain PEEK membranes. Obtaining large ID hollow fibers with substantial transmembrane flux requires sufficient melt strength during spinning to prevent excessive draw of the extruding fiber. The use of a second leachable polymer to the blend satisfies the conditions, and polysulphone (PS) is found to provide superior membranes relative to either poly(etherimide) (PEI) or poly(ether sulphone) (PES) as a second polymer. PEEK membranes obtained by this process yield better chemical resistance to a concentrated warm surfactant/oil solution. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 175–181, 1999     

非溶剂添加剂对聚醚砜酮中空纤维纳滤膜结构和性能的影响

以新型杂萘联苯聚醚砜酮(PPESK)为膜材料,N-甲基-2-吡咯烷酮(NMP)为溶剂,乙二醇甲醚(EGME)、冰醋酸(AA)以及AA/EGME作为复合添加剂,采用干-湿相转化技术制备了中空纤维非对称纳滤膜,重点考察了非溶剂添加剂对中空纤维膜结构和性能的影响。结果表明非溶剂添加剂的加入导致了中空纤维膜孔结构由指状转变为海绵状,从而引起中空纤维膜性能的变化。当聚合物质量分数为23%,铸膜液溶剂体系为m(AA)∶m(EGME)∶m(NMP)=5.7∶16.5∶54.8时,中空纤维膜对PEG600的截留率高于96%,纯水通量为211 L/(m2.h)。     

Synthesis and characterization of poly(ether sulfone) and poly(ether sulfone ketone) copolymers

Poly(ether sulfone) and poly(ether sulfone ketone) copolymers (I–V) were synthesized by the nucleophilic substitution reaction of 4,4′-dihydroxy diphenyl sulfone (DHDPS, A) with various mole proportions 4,4′-difluoro benzophenone (DFBP, B) and 4,4′-difluoro diphenyl sulfone (DFDPS, C) using sulfolane as solvent in the presence of anhydrous K₂CO₃. The polymers were characterized by physicochemical and spectroscopic techniques. All polymers were found to be amorphous, and the glass transition temperature (T_g) was found to increase with the sulfonyl content of the polymers. ¹³C-nuclear magnetic resonance (NMR) spectral data was interpreted in terms of the compositional triads, BAB, BAC, CAC, ABA, and ABB, and indicate that transetherification occurs at high concentration of DFBP units in the polymer (IV). The good agreement between the observed and calculated feed ratios validates the triad analysis. Thermal decomposition studies reveal that the thermal stability of the polymers increases with increase in the carbonyl content in the polymer. Activation energies for thermal decomposition were found to be in the range of 160–203 kJ mol⁻¹ with the cleavage of ϕ SO₂ bond being the preponderant mode of decomposition and depended on the block length of the sulfonyl unit. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2113–2121, 1999     

Performance control of asymmetric poly(phthalazinone ether sulfone ketone) ultrafiltration membrane using gelation

We studied the influence of the gelation conditions on the formation kinetics of the polyphthalazine ether sulfone ketone (PPESK) membrane via wet phase inversion process experimentally and theoretically. Membrane formation and its morphology were first observed with an online optical microscope - CCD camera system. The resulting membranes prepared under various gelation conditions were then characterized by the gelation parameter, optical microscope, and SEM. Lastly, the relationship between the final membrane structure/permeation properties and the gelation parameter was discussed extensively. The results showed that both the gelation rate and the membrane flux increased dramatically as the gelation temperature increased. Moreover, the membrane structures became loose, and the porosity of membrane increased. Different non-solvent could change the solubility parameter between the polymer and the non-solvent, and thus the gelation rate greatly. With the increasing number of carbons in non-solvent, the gelation rate became slow, and the membrane gradually changed from a finger structure into a sponge structure. Adding NMP into the non-solvent changed the difference in the chemical potential and the solubility parameter between the polymer solution and the non-solvent, which in turn changed the gelation rate of polymer solution greatly. With the increasing concentration of NMP in non-solvent, the gelation rate became very slow and sponge structures formed with the non-solvent system of 80% NMP. A novel conclusion could be made that we could control the flux and reject of membrane just by changing the mean diffusion coefficient of skin, D, and the diffusion coefficient of skin, D1, in the process of membrane formation. This work was presented at 13 ^th YABEC symposium held at Seoul, Korea, October 20–22, 2007.     

磷钨酸/二氧化硅/磺化聚醚醚酮复合膜的制备、表征与性能

以二氧化硅和磷钨酸改性磺化聚醚醚酮制得一种新型磺化聚醚醚酮复合膜。复合膜中杂多酸仍然保持着Keggin型PW12O430-阴离子的特征结构,二氧化硅和磷钨酸以无定形状态均匀分散于复合膜中。磷钨酸/二氧化硅/磺化聚醚醚酮复合膜的阻醇性能优于Nafion115;质子导电性能随着温度的提高有所增加。复合膜在磷钨酸中具有良好的稳定性。     

Primary study of novel poly(acrylic sodium)/poly(ether sulfone) composite ultrafiltration membranes (I) the preparation of composite membrane

The poly(acrylic sodium) (PAS)/poly(ether sulfone) (PES) composite ultrafiltration membranes were prepared by coating PAS membrane solution on PES support membrane. The effects of substrate membrane, the composition of PAS solution such as PAS concentration, the choice of the solvent and the additive, and the thickness of PAS active layer on the performance of the composite membranes were extensively investigated. The experimental results have indicated the optimal PAS/PES composite membranes, containing a PES substrate with MWCO of 70,000, together with a PAS top layer having a thickness of about 20 μm, were tested at room temperature and under the pressure of 0.6 MPa with the mass concentration of 0.005 g/L poly(ethylene glycol) (PEG) (Mw = 1000 g/mol) solution, a flux of 32.6 L/(m² h) and a rejection of 92.2% were obtained, which are superior to those of the common commercial membranes reported.     

Synthesis and properties of novel poly(phthalazinone ether ketone ketone)

A novel poly(phthalazinone ether ketone ketone) was prepared via the nucleophilic substitution polycondensation of bis-1,4-(4-chlorobenzoyl)benzene and 4-(4-hydroxyphenyl)-2,3-phthalazin-1-one. The synthesized polymer exhibited high glass-transition temperature, excellent thermooxidative properties, and fair rheological properties. The polymer was soluble in some polar solvents. Electronic friction and membrane properties are also discussed. The results indicate that the polymer falls in the class of high temperature resistance engineering plastics. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 823–826, 2001     

Effects of carbonisation on pore evolution and gas permeation properties of carbon membranes from Kapton polyimide

Carbon membranes were prepared by carbonisation of Kapton^® polyimide at different temperatures under vacuum and nitrogen flow. Pore structure development of the membranes during carbonisation was studied. Carbonisation temperature was critical in the modification of membrane structure. At the same temperature, the carbon membranes fabricated under nitrogen atmosphere had higher gas permeances than those fabricated under vacuum. During heat treatment, the value of d-spacing for the carbon membranes decreased with increasing temperature, however, vacuum and nitrogen atmosphere had different influences on the changes in the d-spacing. CO₂ adsorption showed that the carbon membranes prepared at 1273 K under vacuum had the highest micropore volume whilst the membranes prepared at 1073 K under vacuum had the highest characteristic adsorption energy. N₂ adsorption showed that the samples obtained at 873 K under vacuum had the highest nitrogen uptake. Mesopores were deemed to be connected through micropores and narrow channels between meso- and/or micropores were supposedly present. The micropores predominantly controlled the transport properties of the carbon membranes. The membrane samples obtained at 1173 K under vacuum yielded ideal separation factors of 558.27, 60.87, 19.69 and 138.53 for He/N₂, CO₂/N₂, O₂/N₂ and CO₂/CH₄, respectively, with permeances of 7.26, 0.79, 0.26, 0.13 and 0.006 mol/(m² s Pa) for He, CO₂, O₂, N₂ and CH₄, respectively.     

The state of water in the series of sulfonated poly (phthalazinone ether sulfone ketone) (SPPESK) proton exchange membranes

The different states of water in a series of SPPESK membranes, including sulfonated poly (phthalazinone ether sulfone ketone) (SPPESK) membrane, cross-linked (XL) SPPESK membrane and SPPESK/polyacrylic acid (PAA) semi-interpenetrating polymer network (sIPN) membrane were investigated by low temperature differential scanning calorimetry (DSC) measurements. Only one melting peak was observed for each DSC curve, therefore the free water cannot be distinguished from freezing bound water in the experimental condition. The melting temperature of the freezable water was found to decrease when the content of the freezable water reduced. The content of non-freezing bound water decreased with the increase in total water uptake in each type of the membranes. It indicates that the total water uptake cannot exactly reveal the ability of tight water retention of the membranes. As compared with SPPESK/PAA membrane, SPPESK and XL-SPPESK membranes presented a higher ability of water retention because of higher content of non-freezing bound water measured. A schematic structural model is given to explain the interrelation of distribution of ionic groups (hydrophilic groups) and structure of polymers to the content of non-freezing bound water.     

Micro‐ and ultrafiltration film membranes from poly(ether ether ketone) (PEEK)

Film membranes from the thermoplastic poly(ether ether ketone) (PEEK) have been extruded and tested for their microfiltration and ultrafiltration performance. High‐performance asymmetric membranes have been obtained by extruding polymer blends of PEEK, polysulphone, and a small molecule solvent mixture, and then by removing the polysulphone and solvent in a subsequent extraction step. The process for making ultrafiltration membranes differs from microfiltration membranes only in the relative blend components, and the temperature of the film pick‐up rolls. Processing parameters with important effects on the membrane performance have been identified. Microfiltration membranes are characterized by their pore‐size distributions and SEM, and ultrafiltration membranes by their rejection of bovine serum albumin, bubble point, and SEM. Composite membrane for nanofiltration utilizing the PEEK ultrafiltration membrane as a substrate performed similarly to a commercial membrane for the same purpose. This work details the best method for making PEEK film membranes published to date. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1146–1155, 1999