Gas Permeation Properties Of Poly Research Articles

Effect of Polyurethane Substrate Morphology on Gas Permeation Properties of Poly(dimethyl siloxane) Block Copolymer/Polyurethane Layered Membranes

Effect of Polyurethane Substrate Morphology on Gas Permeation Properties of Poly(dimethyl siloxane) Block Copolymer/Polyurethane Layered Membranes

The effect of poly(alkyl (meth)acrylate) segments on the thermodynamic properties, morphology and gas permeation properties of poly(alkyl (meth)acrylate)-b-poly(dimethyl siloxane) triblock copolymer membranes

The structure-property relationship of the poly(alkyl (meth)acrylate)-b-poly(dimethyl siloxane) (PA-b-PDMS) triblock copolymers were studied for membrane application. The effect of PA segments with different main-chain flexibility and side chains such as poly(benzyl methacrylate) (PBzMA), poly(ethyl methacrylate) (PEMA) and poly(methyl acrylate) (PMA) were studied on the properties of PA-b-PDMS block copolymer membranes. The block copolymers were synthesized via atom transfer radical polymerization (ATRP). The morphology structure of the synthesized block copolymers was changed from spherical to the cylindrical type by changing the structural segments from PMA and P(EMA-b-PEMA) to PEMA, respectively. The morphological feature of the PA-b-PDMS block copolymers was discussed according to their thermodynamic properties (surface energy, the solubility parameter of the constituent segments, and binary interaction parameters). The glass transition temperature of the hard segments of PA-b-PDMS block copolymers was increased by increasing poly(alkyl methacrylate) segments. CO2 permeability of the P(EMA-co-MA)-b-PDMS-b-P(EMA-co-MA) block copolymers was increased (from 7.2 Barrer to 908 Barrer) by increasing MA repeating units which correlated to the higher main chain flexibility of MA compared to the EMA repeating units. Permeability of CO2 was increased 27% by substitution of BzMA repeating units of P(BzMA-co-MA)-b-PDMS-b-P(BzMA-co-MA) block copolymer with EMA and correlated with the lower fractional free volume of BzMA repeating units.

Effect of polymer molecular weight on the physical properties and CO2/N2 separation of pyrrolidinium-based poly(ionic liquid) membranes

Aiming at investigating the effect of the polymer molecular weight (Mw) on the physical and gas permeation properties of poly(ionic liquid)-ionic liquid (PIL–IL) composites, this work focuses on membranes based on variable Mw pyrrolidinium-PILs having [C(CN)3]– as counter-anion and different amounts (20, 40 and 60wt%) of free [C2mim][C(CN)3] IL. Although all the prepared composite materials have high thermal stability (Tonset > 556K) for post-combustion CO2 separation, the evaluation of the film forming ability shows that it is not possible to obtain free standing PIL–IL membranes using the Low Mw PIL (average < 100kDa). The formed Medium Mw (average 200 – 350kDa) and High Mw (average 400 – 500kDa) PIL–IL membranes present similar mechanical properties in terms of Young´s modulus, tensile strength and elongation at break. The gas permeabilities and diffusivities are dependent on the Mw of the PIL used. The Medium Mw PIL–IL membranes display higher CO2 permeabilities (14.6 – 542 Barrer) than those (8.0–439 Barrer) observed for High Mw PIL–IL composites. Despite the Mw of the PIL used, the incorporation of high free IL contents increases both CO2 permeability and CO2/N2 permselectivity. Consequently, the finest CO2/N2 separation performances, overcoming the 2008 upper bound in the Robeson plot, were obtained for the High and Medium Mw PIL–60 IL composites, respectively, with CO2 permeabilities of 439 and 542 Barrer and CO2/N2 permselectivities of 64.4 and 54.0.

Phase segregation and gas permeation properties of poly(urethane urea) bi-soft segment membranes

Segmented poly (urethane urea) membranes, containing two soft segments, poly(propylene oxide) and poly(caprolactone), were prepared by extending a poly(propylene oxide) based tri-isocyanated prepolymer with poly(caprolactone) diol. The membranes synthesized with poly(caprolactone) diol content ranging from 0wt.% to 15wt.% were characterized by infrared spectroscopy (ATR-FTIR). It was concluded that the urethane groups form hard segment aggregates dispersed in the soft segment phase and that this aggregation increases with the increase of poly(caprolactone) content. Gas permeation experiments performed by a photoacoustic system led to the conclusion that permeabilities of CO2 increased from 188 Barrer to 337 Barrer when the poly(caprolactone) membrane content increased from 0wt.% to 10wt.% and was lowest, 113 Barrer, for the membrane containing 15wt.% of PCL. The permeability of O2 through the membranes was independent of poly(caprolactone) content and was between 10 and 11 Barrer. The membrane with the highest CO2 permeability contains 10wt.% of poly(caprolactone) and is characterized by the highest contribution of hydrogen bonding between urethane and urea hard segments.

Effect of Aging on the Gas Permeation Properties of Poly(1-trimethylsilyl-1-propyne)

采用溶液浇铸法,制备了厚度为50～202μm的聚(1-三甲基硅基-1-丙炔)(PTMSP)膜,研究了膜厚度、储存温度以及储存气氛对其气体渗透性能的影响。在室温下储存时,PTMSP膜发生物理老化,气体渗透系数先是迅速下降,然后缓慢降低并趋向平稳。在空气气氛中的下降速率要略大于在N2气气氛中。气体渗透系数的下降速率随膜厚度的减小而增大。在高温(100℃)空气气氛中,受物理及化学老化的共同作用,PTMSP膜气体渗透系数的下降速率进一步增大,IR谱图表明,聚合物氧化生成了CO等极性基团。随储存时间的延长,溶解度系数基本不变,扩散系数的下降是导致气体渗透系数下降的主要原因,这与聚合物体积松弛和(或)致密化及极性基团的形成所造成的自由体积的减小紧密相关。

Effect of natural and synthetic antioxidants incorporation on the gas permeation properties of poly(lactic acid) films

Gas permeation properties (permeability, diffusivity and solubility coefficients) were determined for carbon dioxide and oxygen in poly(lactic acid) (PLA) films enriched with 0, 2, 4 and 10wt.% of different antioxidants, at three temperatures, 284, 293 and 303K, using a time-lag apparatus. Three antioxidants, a natural, α-tocopherol (AT), and two synthetic, butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ), were tested. DSC results show that the polymer glass transition temperature slightly decreases with the increase of the antioxidant content. The crystallinity degree of PLA films decreases with the addition of BHT and TBHQ, whereas the incorporation of AT increases the crystallinity of PLA films. The permeability towards water vapour, at 299K and 45% of relative humidity, and surface energy show a decreased in the wettability of the prepared materials with the increase of the antioxidants content. The incapacity to measure gas permeation in PLA films with 10wt.% of AT and BHT incorporated was due to phase separation, proved by SEM images. The CO2 and O2 permeation results show that PLA barrier properties can be improved by the incorporation of antioxidants but are strongly dependent on the amount and structure of the antioxidant added.

Permeation resistance of poly(ether ether ketone) to hydrogen, nitrogen, and oxygen gases

AbstractWe studied the gas permeation properties of poly(ether ether ketone) (PEEK) and compared it with two other polymers commonly used in the construction of semiconductor microenvironments, polycarbonate (PC), and poly(ether imide) (PEI). The PEEK specimens consisted of extruded films as well as compression‐ and injection‐molded specimens. The compression‐molded specimens were prepared to achieve the highest crystallinity. Injection‐molded disks, representing products, were milled to a prescribed thickness. Permeation, diffusion, and solubility coefficients were measured on these various PEEK specimens for hydrogen, nitrogen, and oxygen gases. It was found that PEEK generally has better permeation resistance than PC or PEI; showing up to five times lower permeation rates than PC or PEI, depending on grade, crystallinity, and gas. The superior permeation resistance of injection‐molded or extruded PEEK, when compared with similarly processed PC or PEI, comes from its crystallinity. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and gas permeation properties of poly(vinyl chloride)‐graft‐poly(vinyl pyrrolidone) membranes

AbstractA series of amphiphilic graft copolymers consisting of poly(vinyl chloride) (PVC) main chains and poly(vinyl pyrrolidone) (PVP) side chains, i.e. PVC‐g‐PVP, was synthesized via atom transfer radical polymerization (ATRP), as confirmed by 1H NMR, FT‐IR spectroscopy, and gel permeation chromatography (GPC). Transmission electron microscope (TEM) and small angle X‐ray scattering (SAXS) analysis revealed the microphase‐separated structure of PVC‐g‐PVP and the domain spacing increased from 21.4 to 23.9 nm with increasing grafting degree. All the membranes exhibited completely amorphous structure and high Young's modulus and tensile strength, as revealed by wide angle X‐ray scattering (WAXS) and universal testing machine (UTM). Permeation experimental results using a CO2/N2 (50/50) mixture indicated that as an amount of PVP in a copolymer increased, CO2 permeability increased without the sacrifice of selectivity. For example, the CO2 permeability of PVC‐g‐PVP with 36 wt% of PVP at 35°C was about four times higher than that of the pristine PVC membrane. This improvement resulted from the increase of diffusivity due to the disruption of chain packing in PVC by the grafting of PVP, as confirmed by WAXS analysis. Copyright © 2011 John Wiley &amp; Sons, Ltd.

The effect of urethane and urea content on the gas permeation properties of poly(urethane-urea) membranes

The effect of urethane and urea contents on gas separation properties of the groups of polyurethane–urea membranes is studied. The membranes used in this study were prepared by polytetramethylene-glycol (PTMG) and isophorone diisocyanate (IPDI) prepolymers. The prepolymers were converted to final polymer using the designed proportion of 1,4-butane diol (BDO) and 1,4-butane diamine (BDA) as a chain extender. Five different BDO/BDA ratios were chosen in order to synthesize poly(urethane-urea)s with different urethane/urea linkage content. The prepared polymers were characterized and the permeability of gases through them was investigated. Results obtained by Fourier transform infrared spectrometer (FT-IR) and differential scanning calorimetery (DSC) indicate that by increasing the urea linkage in the polymers, the microphase separation of hard and soft segments increase. Study of the X-ray diffraction (WAXD) patterns confirmed that polyols may be arranged in small crystalline structures. Permeation measurements of polymers revealed that the permeability of gases decreases with increasing urethane content in the polymers and selectivity of gases decreases with increasing urea content. The solubility and diffusivity of gases indicate solubility domination of gas transport in these membranes. The results of permeability also show high amounts up to 128 Barrer (1 Barrer = 1 × 10 −10 [cm 3 (STP) cm/cm 2 s cm Hg]), and high selectivity for carbon dioxide with respect to nitrogen (CO 2/N 2: 27).

Synthesis and gas permeation properties of poly(diarylacetylene)s having substituted and twisted biphenyl moieties

Diarylacetylene monomers containing substituted biphenyl (1a–f) and anthryl (1g) groups were synthesized and then polymerized with TaCl5-n-Bu4Sn catalyst to produce the corresponding poly(diarylacetylene)s (2a–g). Polymers 2a–f were soluble in common organic solvents such as cyclohexane, toluene, and chloroform. According to thermogravimetric analysis, the onset temperatures of weight loss of the polymers were over 400 °C in air, indicating considerably high thermal stability. Free-standing membranes 2a and 2c–e were prepared by the solution casting method. Desilylation of Si-containing membrane 2c was carried out with trifluoroacetic acid to afford 3c. All the polymer membranes, especially those having twisted biphenyl groups, exhibited high gas permeability; for example, their oxygen permeability (PO2) values ranged from 130 to 1400 barrers. Membrane 2d having two chlorine atoms in the biphenyl group showed the highest gas permeability (PO2 = 1400 barrers) among the present polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 861–868, 2010

CO 2 permeation properties of poly(ethylene oxide)-based segmented block copolymers

This paper discusses the gas permeation properties of poly(ethylene oxide) (PEO)-based segmented block copolymers containing monodisperse amide segments. These monodisperse segments give rise to a well phase-separated morphology, comprising a continuous PEO phase with dispersed crystallised amide segments. The influence of the polyether phase composition and of the temperature on the permeation properties of various gases (i.e., CO 2, N 2, He, CH 4, O 2 and H 2) as well as on the pure gas selectivities were studied in the temperature range of −5 °C to 75 °C. The CO 2 permeability increased strongly with PEO concentration, and this effect could partly be explained by the dispersed hard segment concentration and partly by the changing chain flexibility. By decreasing the PEO melting temperature the low temperature permeabilities were improved. The gas transport values were dependant on both the dispersed hard segment concentration and the polyether segment length (length between crosslinks). The gas selectivities were dependant on the polyether segment length and thus the chain flexibility.

Gas permeation properties of poly(2,5-dialkyl-p-phenyleneethynylene) membranes

Dipropynylbenzenes with alkyl groups (CH3C ≡ CRC6H2RC≡CCH3, R=n-C6H13, n-C8H17, n-C10H21, 1a–c, respectively) were polymerized with Mo(CO)6 to afford solvent-soluble poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c). The polymers (2a–c) had high molecular weight over 3×104, and gave free-standing membranes by solution casting method. According to thermogravimetric analysis (TGA), these poly(p-phenyleneethynylene)s showed high thermal stability (T0 ≥380 °C). The densities of membranes of poly(2,5-dialkyl-p-phenyleneethynylene)s (2a–c) were 0.936–0.965, and their fractional free volume (FFV) were relatively large (ca. 0.14–0.15). The oxygen permeability coefficients (PO2) of membranes of 2a–c were 4.88, 7.06, and 16.6 barrers, respectively.

Gas permeation properties of poly(lactic acid) revisited

Pure gas permeation through solution-cast amorphous poly(lactic acid) (PLA) films is investigated using the time-lag method. New data on permeability, diffusivity and solubility for N 2, O 2 and CO 2 are reported. At 30 °C, N 2 permeability, diffusivity and solubility in PLA (98.7% L, 1.3% D) are 0.05 Barrer, 2.4 × 10 −8 cm 2/s, and 2.2 × 10 −4 cm 3 (STP)/cm 3 (polymer) cmHg. The measured activation energy of N 2 permeation is 34.6 kJ/mol. For O 2, the corresponding values are 0.26 Barrer, 5.7 × 10 −8 cm 2/s, 4.9 × 10 −4 cm 3 (STP)/cm 3 (polymer) cmHg and 24.0 kJ/mol. The values for CO 2 are 1.10 Barrer, 4.4 × 10 −9 cm 2/s, 0.025 cm 3 (STP)/cm 3 (polymer) cmHg and 18.0 kJ/mol. These new measurements of the gas permeation properties of poly(lactic acid) (PLA) show considerable disagreement with previously reported results [H.J. Lehermeier, J.R. Dorgan, J.D. Way, Gas permeation properties of poly(lactic acid), J. Membr. Sci. 190 (2001) 243–251] obtained using a continuous flow apparatus. The effect of PLA optical compositions on permeation is also investigated and found to be consistent with the earlier report; the L/ D ratio has no effect on the permeation properties provided the material is quenched into an amorphous state. The ability to generate diffusivity and solubility data along with the greater sensitivity of pressure measurement over gas composition argues in favor of the use of the time-lag apparatus for pure gas permeability measurements and suggests that the revised PLA permeation values reported here should be adopted.

Synthesis and gas permeation properties of poly(diphenylacetylenes) having bulky alkyl/silyl and hydroxy groups

Novel diphenylacetylene monomers 1c– h possessing tert-butyl or trialkylsilyl and siloxy groups ( p-R-C 6H 4C CC 6H 4– p-OSiMe 2 t-Bu: 1c R = t-Bu, 1e R = SiMe 3, 1g R = SiMe 2 t-Bu; p-R-C 6H 4C CC 6H 4– m-OSiMe 2 t-Bu: 1d R = t-Bu, 1f R = SiMe 3, 1h R = SiMe 2 t-Bu) were polymerized with TaCl 5– n-Bu 4Sn catalyst. Monomers 1c and 1e gave high molecular weight polymers in good yields. Free-standing membranes of polymers 2c– f were fabricated by casting from toluene solution. Desilylation of membranes of polymers 2c and 2d with trifluoroacetic acid (TFA) yielded poly(diphenylacetylenes) having tert-butyl and hydroxy groups ( 3c and 3d). Polymers 2c– f and 2h were soluble in nonpolar solvents such as hexane, cyclohexane and toluene, while 3c and 3d were insoluble in these solvents. According to thermogravimetric analysis (TGA), 2c– f, 3c and 3d exhibited high thermal stability. The gas permeability of all the membranes in the present study was much higher than that of the corresponding polymers without bulky groups, indicating that incorporation of bulky groups into the polymers improves the gas permeability. The PCO 2/ PN 2 permselectivity ratios of polymers 3c and 3d were 23 and 14, respectively. The CO 2 permeability and CO 2/N 2 permselectivity of 3c and 3d were positioned above Robeson's upper bound line.

Gas transport properties of segmented poly(ether siloxane urethane urea) membranes

Poly(ether siloxane urethane urea) with different polysiloxane contents were synthesized and characterized. The single gas permeation properties of poly(ether siloxane urethane urea) membranes were determined at 30 °C for O 2, N 2, CO 2, CH 4, n-C 4H 10. Their structures and gas permeation properties were compared. Significant correlation among the polysiloxane soft segment with the permeation properties was found. In addition, an analysis of the viability to use these membranes for n-C 4H 10/CH 4 separation was made. A membrane with interesting properties such as higher n-C 4H 10/CH 4 selectivity for a mixture of gases than for single gases was obtained, indicating a possibility of application of the poly(siloxane urethane) membranes for n-C 4H 10/CH 4 separation.

Gas permeation properties of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) derived carbon membranes prepared on a tubular ceramic support

The carbon membranes were prepared by the pyrolyisis of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) polymer coated on the surface of the macroporous alumina tubular ceramic support. The permeation results showed that gas transport through the PPO derived carbon membranes was controlled by the molecular sieving effect. The influence of the pyrolysis temperature on the permeation performances indicates that the pore structure developed at a low temperature and then the pore characteristic values (pore volume, surface area, etc.) were increased with increasing pyrolysis temperatures, and decreased at further temperature. The correlation of the permeability versus the permselectivity for the PPO derived carbon membranes showed higher values than the upper bounds for polymeric membranes, and excellent performance comparable to polyimides derived carbon membranes.

Synthesis and gas permeation properties of poly(dialkylacetylenes) containing isopropyl-terminated side-chains

Gas permeabilities of a systematic series of glassy, isopropyl-based poly(dialkylacetylenes) for He, H 2, N 2, O 2, CH 4, CO 2, C 2H 6, and C 3H 8 were determined at temperatures from 25 to 55 °C. Poly(4-methyl-2-pentyne) [PMP] has the highest fractional free volume (FFV) and, therefore, the highest gas permeability of all known isopropyl-based poly(dialkylacetylenes). For example, the nitrogen permeability of PMP at 35 °C is 1250 Barrers (1 Barrer = 1 × 10 −10 cm 3 (STP) cm/cm 2 s cmHg), one of the highest permeabilities reported to date. The high gas permeabilities of PMP result from very poor polymer chain packing due to alternating rigid double bonds along the main chain and a very bulky, sterically hindering isopropyl side-chain. Here, we report on the influence of the side-chain length on the pure- and mixed-gas permeation properties of two related isopropyl-based poly(dialkylacetylenes), namely, poly(5-methyl-2-hexyne) [P5M2H] and poly(6-methyl-2-heptyne) [P6M2H]. The gas permeabilities in this series of acetylene-based polymers decrease significantly as the length of the alkyl side-chain increases. For example, the nitrogen permeabilities of P5M2H and P6M2H at 35 °C are 13- and 24-fold lower than that of PMP, respectively. An increase in side-chain length also has significant effects on the temperature dependence of gas permeation and the mixed-gas permeation properties of the polymers. An increase in side-chain length leads to a significant increase in the activation energy of permeation, indicating that the chain-packing density in long-chain isopropyl-based poly(dialkylacetylenes) is higher than that in PMP. This trend is further reflected in the mixed-gas permeation properties of the branched side-chain poly(dialkylacetylenes); both the n-butane permeability and the n-butane/methane selectivity decrease as the length of the alkyl side-chain increases.

Gas Permeation Properties of Poly(1,1‘-dihydroperfluorooctyl acrylate), Poly(1,1‘-dihydroperfluorooctyl methacrylate), and Poly(styrene)-b-poly(1,1‘-dihydroperfluorooctyl acrylate) Block Copolymers

The permeabilities of rubbery poly(1,1‘-dihydroperfluorooctyl acrylate) (PFOA), glassy poly(1,1‘-dihydroperfluorooctyl methacrylate) (PFOMA), and poly(styrene)-b-poly(1,1‘-dihydroperfluorooctyl acr...

日本膜学会第２３年会特別講演 置換ポリアセチレン膜の創成，特性，および機能

This review article surveys the synthesis and properties of substituted polyacetylenes, especially those which exhibit high gas permeability, such as poly [1- (trimethylsilyl) -1-propyne] [poly (TMSP)] and poly (diphenylacetylene) [poly (DPA)] derivatives. Poly (TMSP) having high molecular weight up to around 1 × 106 can be obtained by the metathesis polymerization of TMSP catalyzed by TaCl5 and NbCl5. This polymer is characterized by good solubility in many common solvents, formation of tough films by solution casting, a high glass transition temperature (> 250 °C), and fairthermal stability. Its oxygen permeability (Po2) at 25 °C reaches ca. 6, 000 barrers, which is the highest value of all existing polymers. The gas permeation properties of poly (TMSP) are reviewed. The TaCl5/n-Bu4Sn system is effective for the polymerization of DPAs. Most of the produced polymers are soluble in organic solvents, thermally highly stable, and film-forming by solution casting. Interestingly, large Po2 values (1, 100 barrers) are observed with poly (DPAs) bearing bulky spherical para-substituents. Desilylation of p-Me3Si-containing poly (DPA) membrane yields poly (DPA) membrane, which shows high Po2 of-6, 000 barrers.

１‐トリメチルシリル‐１‐プロピンと１‐フェニル‐１‐プロピンから構成されるコポリマーとブレンド膜の気体透過性の温度依存

The temperature dependence of the gas permeation properties of poly (1-trimethylsilyl-1-propyne) [PMSP] /poly (1-phenyl-1-propyne) [PPP] blends and poly (TMSP-co-PP) films was studied. As PP content increases, the activation energies of permeation (Ep) and diffusion (ED) for various gases in these materials increase, but no distinct change in the heat of solution (ΔHs) is observed. The increase in Ep is due to an increase in ED. All ED values are positive, while all ΔHs values are negative. In pure PMSP, Ep is negative for most gases because |ED| is much smaller than |ΔHs|. When the PP content exceeds 40 vol% in poly (TMSP-co-PP), however, Ep becomes positive because |ED| is now larger than |ΔHs|. Furthermore, Ep decreases with increasing critical temperature (Tc) of the penetrants because ΔHs decreases more than ED increases. After storage in air, the gas permeabilities of thin PMSP/PPP (9 : 1) blend films are found to be much lower than those of thin poly (TMSP-co-PP) (9 : 1) films. However, no substantial difference between the activation energies of permeation in these aged blend and copolymer films is observed. The gas permeabilities of thin poly (TMSP-co-PP) films are reduced even further after thermal treatment.This permeability reduction is a consequence of a larger Ep in the heat-treated, copolymer films. Ep is higher because of an increase in ED due to densification of these films by thermal treatment.