Gas permeation properties of blend and copolymer membranes composed of 1-trimethylsilyl-1-propyne and 1-phenyl-1-propyne structures

The poly(1-trimethylsilyl-1-propyne) (PMSP) has the potential to be an important membrane gas separation material due to the fact that it has the highest gas permeability of all polymeric membranes. One problem with PMSP is a decrease in the gas permeability with age. In order to understand the aging processes, we studied the change in free volume and the molecular motions of the PMSP and its membranes modified with 1-phenyl-1-propyne (PP) structures; that is, a copolymer and a blend of PMSP and PPP. During aging, the unrelaxed volume of the PMSP membrane was relaxed, and the molecular motion of carbons dropped, suggesting that the decrease in the microvoids caused a tighter chain packing. The copolymer and blend membrane had stable permeability compared to the PMSP. In particular, the addition of a small amount of the PP structure provided excellent stability with high gas permeability. A decrease in the unrelaxed volume of modified membranes was hardly observed with age; however, the molecular motion of some carbons slightly changed. This change did not affect the gas permeability. In this case, a larger unrelaxed volume was probably a dominant factor in the gas permeation of the PMSP rich membranes relative to the molecular motion in the T₁ measurement. © 1997 John Wiley & Sons, Inc.     

Hydrocarbon/hydrogen mixed gas permeation in poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and PTMSP/PPP blends

The gas permeation properties of poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and blends of PTMSP and PPP have been determined with hydrocarbon/hydrogen mixtures. For a glassy polymer, PTMSP has unusual gas permeation properties which result from its very high free volume. Transport in PPP is similar to that observed in conventional, low-free-volume glassy polymers. In experiments with n-butane/hydrogen gas mixtures, PTMSP and PTMSP/PPP blend membranes were more permeable to n-butane than to hydrogen. PPP, on the other hand, was more permeable to hydrogen than to n-butane. As the PTMSP composition in the blend increased from 0 to 100%, n-butane permeability increased by a factor of 2600, and n-butane/hydrogen selectivity increased from 0.4 to 24. Thus, both hydrocarbon permeability and hydrocarbon/hydrogen selectivity increase with the PTMSP content in the blend. The selectivities measured with gas mixtures were markedly higher than selectivities calculated from the corresponding ratio of pure gas permeabilities. The difference between mixed gas and pure gas selectivity becomes more pronounced as the PTMSP content in the blend increases. The mixed gas selectivities are higher than pure gas selectivities because the hydrogen permeability in the mixture is much lower than the pure hydrogen permeability. For example, the hydrogen permeability in PTMSP decreased by a factor of 20 as the relative propane pressure (p/p_sat) in propane/hydrogen mixtures increased from 0 to 0.8. This marked reduction in permanent gas permeability in the presence of a more condensable hydrocarbon component is reminiscent of blocking of permanent gas transport in microporous materials by preferential sorption of the condensable component in the pores. The permeability of PTMSP to a five-component hydrocarbon/hydrogen mixture, similar to that found in refinery waste gas, was determined and compared with published permeation results for a 6-Å microporous carbon membrane. PTMSP exhibited lower selectivities than those of the carbon membrane, but permeability coefficients in PTMSP were nearly three orders of magnitude higher. © 1996 John Wiley & Sons, Inc.     

Polymer characterization and gas permeability of poly(1-trimethylsilyl-1-propyne) [PTMSP], poly(1-phenyl-1-propyne) [PPP], and PTMSP/PPP blends

Pure gas and hydrocarbon vapor transport properties of blends of two glassy, polyacetylene-based polymers, poly(1-trimethylsilyl-1-propyne) [PTMSP] and poly(1-phenyl-1-propyne) [PPP], have been determined. Solid-state CP/MAS NMR proton rotating frame relaxation times were determined in the pure polymers and the blends. NMR studies show that PTMSP and PPP form strongly phase-separated blends. The permeabilities of the pure polymers and each blend were determined with hydrogen, nitrogen, oxygen, carbon dioxide, and n-butane. PTMSP exhibits unusual gas and vapor transport properties which result from its extremely high free volume. PTMSP is more permeable to large organic vapors, such as n-butane, than to small, permanent gases, such as hydrogen. PPP exhibits gas permeation characteristics of conventional low free volume glassy polymers; PPP is more permeable to hydrogen than to n-butane. In PTMSP/PPP blends, both n-butane permeability and n-butane/hydrogen selectivity increase as the PTMSP content of the blends increases. © 1996 John Wiley & Sons, Inc.     

Phase equilibrium and rheology of poly(1-trimethylsilyl-1-propyne) solutions

The phase equilibrium and rheological properties of poly(1-trimethylsilyl-1-propyne) solutions obtained with tantalum catalysts are studied. For three polymers with different molecular masses, phase diagrams are determined in a number of solvents. From these diagrams, the Hansen solubility parameters of poly(1-trimethylsilyl-1-propyne) are calculated by the method proposed in this work. Dilute solutions of poly(1-trimethylsilyl-1-propyne) behave as Newtonian liquids, whereas the viscosity of viscoelastic concentrated systems decreases as the shear rate grows. The molecular and rheological characteristics of studied poly(1-trimethylsilyl-1-propyne) samples are compared with the samples prepared with NbCl₅ catalysts. Poly(1-trimethylsilyl-1-propyne) obtained with a catalytic system involving tantalum pentachloride is characterized by high intrinsic viscosity and solution viscosity compared to poly(1-trimethylsilyl-1-propyne) prepared with niobium catalyst. The difference in properties is due to the dissimilar ratios of cis and trans units in the samples.     

Chemical modification of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) using highly reactive metallating systems

Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are metallated using normal and secondary butyllithium chelate complexes with tetramethylethylenediamine and superbases based on complexes of normal and secondary butyllithium with potassium tert-pentoxide as metallating agents. Optimal conditions ensuring metallation of poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) with a high yield without degradation of macrochains are determined. Poly(vinyltrimethylsilane) and poly(1-trimethylsilyl-1-propyne) are functionalized via reactions of metallated polymers with CO₂, trimethylsilyl chlorosulfone, diethyl disulfide, and ethylene oxide. COOH, SO₃H, OH, and thioester groups are introduced into poly(vinyltrimethylsilane), and SO₃H and COOH groups are incorporated into poly(1-trimethylsilyl-1-propyne). Upon introduction of carboxyl groups into poly(vinyltrimethylsilane), its hydrophilicity and permselectivity with respect to H₂O/N₂, H₂O/H₂, and H₂O/CH₄ pairs increase. The introduction of SO₃H groups into poly(1-trimethylsilyl-1-propyne) and poly(vinyltrimethylsilane) leads to the appearance of proton conductivity of these polymers.     

Facilitated transport of molecular oxygen in cobaltporphyrin/poly(1-trimethylsilyl-1-propyne) membrane

The combination membrane of poly(1-trimethylsilyl-1-propyne) with enormously high permeability and poly(vinylimidazole)-bound porphinatocobalt with selective oxygenbinding ability was prepared. Oxygen transport through the membrane was facilitated in terms of oxygen transport via the latter domain as a fixed oxygen-carrier, and this oxygen permeability maintained for a month.     

Chromatographic properties and polarity evaluation of poly(1-trimethylsilyl-1-propyne) and poly(1-phenyl-1-propyne)

The chromatographic properties of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-phenyl-1-propyne) (PPP) were studied by gas chromatography using packed columns. The selectivity and efficiency of columns packed with PTMSP and PPP were compared to the data obtained for columns with other known adsorbents and stationary phases. The McReynolds and Rohrschneider constants, on the basis of which the polarity of the new phases was evaluated, were calculated. The results of the investigation of chromatographic properties allow PTMSP to be brought in line with the polymeric adsorbents Porapak Q, Porapak QS, and Chromosorb 106, while PPP, with the methyphenylsilicon phases SE-52 and OV-3.     

Chromatographic and adsorption properties of the mixed stationary phase poly(1-trimethylsilyl-1-propyne)/poly(1-phenyl-1-propyne)

Adsorption and chromatographic properties of the mixed stationary phase poly-(1-trimethylsilyl-1-propyne)/poly(1-phenyl-1-propyne) (PTMSP/PPP) composed as 97: 3 by weight have been investigated by methods of low-temperature nitrogen adsorption and gas chromatography on packed columns. The resultant phase has uniform mesoporous structure. The chromatographic properties of the mixed phase are significantly different from the properties of the original porous polymers PTMSP and PPP. The adsorbent obtained by modifying Chromosorb P NAW with a mixture of polymers provides the selective separation of chlorosubstituted, saturated, and aromatic hydrocarbons.     

老化对聚(1-三甲基硅基-1-丙炔)气体渗透性能的影响

采用溶液浇铸法,制备了厚度为50~202 μm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。     

Pure hydrocarbon sorption properties of poly(1-trimethylsilyl-1-propyne) (PTMSP), poly(1-phenyl-1-propyne) (PPP), and PTMSP/PPP blends

Propane and n-butane sorption in blends of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-phenyl-1-propyne) (PPP) have been determined. Solubilities of propane and n-butane increased as the PTMSP content in the blends increased. This result is consistent with the higher free volume of PTMSP-rich blends and the better thermodynamic compatibility between PTMSP and these hydrocarbons. Propane and n-butane sorption isotherms were well described by the dual-mode model for sorption in glassy polymers. PTMSP/PPP blends are strongly phase-separated, heterogeneous materials. A noninteracting domain model developed for sorption in phase-separated glassy polymer blends suggests that sorption in the Henry's law regions (i.e., the equilibrium, dense phase of the blends) is consistent with the model. However, Langmuir capacity parameters in the blends are lower than predicted from the domain model, suggesting that the amount of nonequilibrium excess free volume associated with the Langmuir sites depends on blend composition. © 1996 John Wiley & Sons, Inc.     

An investigation of the high gas permeability of poly (1-Trimethylsilyl-1-Propyne)

The permeability of poly (1–trimethylsilyl–1−propyne), PMSP, to light gases is higher than that of any other nonporous synthetic polymer at ambient temperatures. PMSP is in the glassy polymer state at these temperatures. Permeability, diffusion, and solubility coefficients were determined for N₂, O₂, CH₄, and CO₂ in PMSP, and are compared with values reported for these gases in poly (dimethyl siloxane). The higher gas permeability of PMSP results primarily from a substantial gas solubility, which appears to be due, in turn, to a large “excess” free volume in the unrelaxed (Langmuir) domains of this glassy polymer. The structure of PMSP, which consists of relatively rigid backbone chains separated by bulky trimethylsilyl side groups, probably is responsible for this large free volume.     

Chemical modification of poly(substituted-acetylene). I. Synthesis and gas permeability of poly(1-trimethylsilyl-1-propyne)/poly (dimethylsiloxane) graft copolymer

In order to improve the selectivity and the stability and the stability for gas permeation of poly (1-trimethylsilyl-1-propyne) (PTMSP) membrane, it was chemically modified by grafting polydimethylsiloxane (PDMS) chains. The graft copolymers were synthesized by four different methods via metallation of PTMSP with n-butyllithium. PDMS content of the graft co-polymers was controlled in the range of 4–92 mol %. Very tough, thin membranes could be prepared from these graft copolymers using a solvent casting method. Thermal property and gas permeability of the copolymer membranes thus obtained were evaluated. These membranes were relatively thermally stable, and the softening points were over about 150°C. Oxygen permeability coefficients Po₂ and selectivity Po₂/PN₂ of PTMSP/PDMS graft copolymers depended on the PDMS content, the former was in the range of 1 X 10^?8 to 2 × 10^?7 cm³ (STP)· cm/(cm²· s · cm. Hg) and the latter was 2.0–3.1. Minimum values of PO₂ and PN₂ occured at PDMS content of about 55 mol %. The introduction of more than 60 mol % of PDMS resulted in oxygen permeability coefficient which was maintained for more than one moth (PO₂ = 2 ? 6 × 10 ^?8 cm ³ (STP)· cm/(cm²·s·cm Hg), PO₂/PN₂ = 2.3–2.7).     

Separation of hydrocarbon and sulfur-containing gases on a new poly-(1-trimethylsilyl-1-propyne)/poly-(1-phenyl-1-propyne) mixed stationary phase in the presence of water

The separation of hydrocarbons (methane, ethane, propane, n-butane, ethylene, and propylene) and sulfur-containing gases (hydrogen disulfide, sulfur dioxide, carbonyl sulfide) on a new mixed stationary phase poly-(1-trimethylsilyl-1-propyne)/poly-(1-phenyl-1-propyne) in the presence of water has been studied by gas chromatography. It has been demonstrated that the new mixed stationary phase outperforms the known polymeric adsorbents and stationary phases by resolution, asymmetry factor, and column efficiency.     

GAS PERMEABILITY OF COPOLY(1-TRIMETHYL-SILYL-1-PROPYNE-PENTAMETHYL-DISILYL-1-PROPYNE) MEMBRANE

The permeability of copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-1-propyne) membrane for twelve gases (0_2, N_2, CO_2, H_2, D_2, He, At, CH_4, C_2H_4, C_2H_6, C_3H_6 and C_3H_8) was examined. The basic laws of solution and diffusion of the gases in the membrane were expounded preliminarily. It was found that a linear relationship between logarithm of diffusion coefficient (D) and critical molar volume (V_c) of the gases. The permeation characteristics of the gases in the copoly (1-trimethylsilyl-1-propyne-pentamethyldisilyl-1-propyne) membrane was also discussed.     

Macrochain configuration, stucture of free volume and transport properties of poly(1-trimethylsilyl-1-propyne) and poly(1-trimethylgermyl-1-propyne)

The relationship between poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(1-trimethylgermyl-1-propyne) (PTMGP) microstructure, gas permeability and structure of free volume is reported. n-Butane/methane mixed-gas permeation properties of PTMSP and PTMGP membranes with different cis-/trans-composition have been investigated. The n-butane/methane selectivities for mixed gas are by an order higher than the selectivities calculated from pure gas measurements (the mixed-gas n-butane/methane selectivities are 20?C40 for PTMSP and 22?C35 for PTMGP). Gas permeability and n-butane/methane selectivity essentially differ in polymers with different cis-/trans-composition. Positron annihilation lifetime spectroscopy investigation of PTMSP and PTMGP with different microstructure has determined distinctions in total amount and structure of free volume, i.e. distribution of free volume elements. The correlation between total amount of free volume and gas transport parameters is established: PTMSP and PTMGP with bigger free volume exhibit higher n-butane permeability and mixed-gas n-butane/methane selectivity. Such behavior is discussed in relation to the submolecular structure of polymers with different microstructure and sorption of n-butane in polymers with different free volume.     

Electrooptical and Conformational Properties of Poly(1-Trimethylsilyl-1-Propynes) with Different Chain Microstructures

The methods of the Kerr effect and solution hydrodynamics were applied to study the electrooptical and hydrodynamic properties of samples of disubstituted polyacetylenes, poly(1-trimethylsilyl-1-propynes), prepared by polymerization of 1-trimethylsilyl-1-propyne with NbCl₅ and TaCl₅/BuLi as catalysts. The experimental electrooptical characteristics of polymers were compared with those calculated by PM3 semiempirical quantum-chemical method.     

Gas transport in TiO2 nanoparticle-filled poly(1-trimethylsilyl-1-propyne)

Titanium dioxide (TiO₂) nanoparticles were dispersed via solution processing in poly(1-trimethylsilyl-1-propyne) (PTMSP) to form nanocomposite films. Nanoparticle dispersion was investigated using atomic force microscopy and transmission electron microscopy. At low-particle loadings, nanoparticles were dispersed individually and in nanoscale aggregates. At high-particle loadings, some nanoparticles formed micron-sized aggregates. The gas transport and density exhibited a strong dependence on nanoparticle loading. At low-TiO₂ loadings, the composite density was similar to or slightly higher than that predicted by a two-phase additive model. However, at particle loadings exceeding approximately 7 nominal vol.%, the density was markedly lower than predicted, suggesting that the particles induced the creation of void space within the nanocomposite. For example, when the TiO₂ nominal volume fraction was 0.35, the polymer/particle composite density was 40% lower than expected based on a two-phase additive model for density. At low-nanoparticle loading, light gas permeability was lower than that of the unfilled polymer. At higher nanoparticle loadings, light gas permeability (i.e., CO₂, N₂, and CH₄) increased to more than four times higher than in unfilled PTMSP. At most, selectivity changed only slightly with particle loading.     

Chromatographic properties of poly(1-phenyl-1-propyne)

The chromatographic properties of poly(1-phenyl-1-propyne) (PPP) were studied by separating the C₁–C₁₀ hydrocarbons, alcohols, aromatic, and sulfur-bearing compounds. The influence of the phase percentage for polymer adsorbent (Polysorb-1) on the process of component retention was investigated. A comparison of PPP and the nonpolar liquid phase SE-52 widely used in gas chromatography was performed.     

Copolymerization of 4-methyl-2-pentyne with 1-trimethylsilyl-1-propyne and 1-trimethylgermyl-1-propyne with Nb-containing catalysts

It has been shown that the copolymerization of 4-methyl-2-pentyne with 1-trimethylsilyl-1-propyne or 1-trimethylgermyl-1-propyne with the use of niobium pentachloride-based catalytic systems in the presence of Ph₃Bi, Et₃SiH, and Bu₄Sn as cocatalysts yields corresponding copolymers of various compositions. The technique of determining the composition of copolymers from their IR spectra has been developed. The reactivity ratios of the monomers have been estimated. It has been demonstrated that these values increase in a sequence 4-methyl-2-pentyne > 1-trimethylsilyl-1-propyne > 1-trimethylgermyl-1-propyne.     

Silica filled poly(4-methyl-2-pentyne) nanocomposite membranes: Similarities and differences with poly(1-trimethylsilyl-1-propyne)–silica systems

The performance of poly(4-methyl-2-pentyne) (PMP)/silica nanocomposites was studied for membranes with a filler content between 10 and 40 wt%. An increase in permeability and a constant vapor selectivity were measured with increasing filler content. The constant selectivity was in contrast to earlier published results for silica filled poly(1-trimethylsilyl-1-propyne) (PTSMP) membranes. Therefore, a comparison between both materials was made. Free volume sizes and interstitial mesopore sizes were determined by use of positron annihilation lifetime spectroscopy (PALS) and image analysis was performed on transmission electron microscopy (TEM) pictures of both materials. Although both materials possessed interstitial mesopores, a difference in membrane structure was noticed, explaining the difference in membrane performance.