聚[1—（三甲硅基）1—丙炔]—一种有希望的气体分离膜材料

聚[1-(三甲硅基)]-丙炔(PTMSP)膜的气体透过速率高于目前已知的,不管在室温是玻璃态还是橡胶态的任何聚合物.PTMSP在室温是玻璃态.PTMSP的高透气性主要来源于极高的对气体溶解度及高扩散系数,而这是因为在这种玻璃态聚合物中,有大量处于非松弛区域的自由体积.PTMSP的最大问题是它的高透气性随着时间的过去和热历史而衰减.近来,为解决这一问题进行了大量的努力,如加入低挥发材料,氟化、溴化,与其它单体共聚,与其它聚合物共混等.     

聚酰亚胺6FDA-mPDA及其非对称中空纤维膜的气体渗透性能

用两步法制备了聚酰亚胺2,2＇-双（3,4-二羧酸苯基）六氟丙烷二酐（6FDA）-1,3-苯二胺（mPDA）．测定了聚合物致密膜的密度、自由体积分率和玻璃化转变温度．制备了不同干纺距离下具有超薄致密皮层的聚酰亚胺中空纤维膜．制备的中空纤维膜在25℃,0．5MPa下,O2的渗透速率为19．10GPU,O2／N2分离系数为5．99,CO2的渗透速率为106．34GPU,CO2／CH4的分离系数为82．00．致密皮层的厚度约为96nm．考察了操作温度对膜性能的影响,结果表明,随着温度的升高,膜的渗透速率增大,分离系数减小．物理老化对膜性能的实验结果表明,随着老化时间的增加,膜的渗透速率减小,分离系数增大．膜的致密层厚度影响膜的老化性能．     

含有联苯侧基聚乙炔的合成及其气体渗透性能

合成了含有取代联苯及烷基硅取代基的二芳基乙炔单体（1a~1d）,以TaCl5-n-Bu4Sn作催化剂聚合得到聚合物2a、2b和2d。 所得聚合物在常规有机溶剂中具有良好的溶解性。 用聚合物2a和2b的甲苯溶液浇铸制备了均质膜。 采用三氟乙酸对聚合物2a和2b膜进行去硅化反应,制备了不溶性膜3a和3b。 热重分析表明,所得聚合物均具有高的热稳定性,在空气中的热失重起始温度分别为340和430 ℃。 聚合物2a和2b的氧气渗透系数（PO2)分别为260和390 barrers,去硅化膜3a和3b的PO2分别下降至73和180 barrers。 聚合物膜的O2/N2分离系数为2.4~3.3,并随PO2的增加而减小。 由气体在聚合物膜中的扩散系数和溶解系数的测定,扩散系数的降低是导致去硅化膜气体渗透系数下降的主要原因。     

聚1—三甲硅基丙炔膜的溴化和气体透过性

在新的气体分离膜材料中,聚1-三甲硅基丙炔(PTMSP)以其高的气体透过性和优异的成超薄膜性而引起各方面的兴趣。目前的研究热点是如何提高PTMSP的氧氮透过分离系数(ao_2/N_2)和气体透过稳定性。Langsam用氮稀释的氟气对PTMSP膜进行表面氟化处理,大幅度地提高了膜的ao_2/N_2,但处理过程中伴随着剧烈的裂解,控制困难。Gozds以N-溴代丁     

聚1—三甲硅基丙炔的改性及其氧氮透过性

80年代才研制的聚1-三甲硅基丙炔(PTMSP)的T_g高于200℃,而它在室温的气体透过性呈橡胶态聚合物的特性,透氧和透醇速率极高,Po_2达5×10~3Barrer,是一代新型富氧膜材料。但TMSP制备和聚合难度大。目前尚只有日、美等国取得一些进展,他们     

氟涂层对聚合物-钴卟啉膜氧气输送性能及其寿命的影响

采用在聚合物-钴卟啉(CoP)膜表面旋转涂覆氟涂料法,制备了氧/氮分离膜.研究表明,与未涂层膜相比,氟涂层膜中的CoP与氧表观结合平衡常数、膜的氧渗透系数和氧/氮选择性没有发生明显变化.随氟涂层厚度增加,氧渗透系数稍有降低,但水蒸汽渗透系数显著降低.由于氟涂层的憎水性,使涂层膜的水蒸汽渗透系数显著降低,氧载体CoP与氧结合寿命延长了4倍.     

含芳环的可聚合阳离子型Hydrotrope的自缔合行为和助溶性能

采用尼罗红(Nile red)染料为探针,利用吸收和发射光谱研究了具有不同烷芳基结构的可聚合阳离子型Hydrotropes(PCHs)的溶液性质,结果表明其在水溶液中易发生自缔合行为并具有两个阈值浓度:分子开始自缔合的临界浓度(CAC)(10-1—10-2 mol/L),开始大幅度提高助溶作用的最小助溶浓度(MHC)(>10-1 mol/L),两阈值浓度均随化合物分子结构中的疏水基团尺寸的增大而减小.两亲化合物聚集体的微环境极性测定的结果显示,其极性比表面活性剂胶束高,并且随着化合物浓度的增大不断下降,表明形成的聚集体结构比较疏松,且其分子堆砌密度随聚集体的增大而逐步升高.此外,通过自由基聚合得到相应的两亲聚合物仍保留Hydrotrope原有的性能,并具有更显著的助溶作用.     

树枝形聚合物修饰的双8-羟基喹啉光物理研究

研究了树枝形聚合物修饰的双8-羟基喹啉衍生物(Gn-QMQ, n=1~3)在二氯甲烷和乙腈中的荧光猝灭过程和荧光衰减过程. 随着代数n的增加, 猝灭速率常数减小, 核心双8-羟基喹啉基团荧光寿命增长, 非辐射失活速率常数减小. 研究结果表明, 随着代数的增加, 树枝形骨架对核心基团的位点分离作用增大, 在乙腈中树枝形骨架趋于紧密构象, 具有更强的位点分离作用.     

富羧酸基团的共轭微孔聚合物:结构单元对孔隙和气体吸附性能的影响（英文）

共轭微孔聚合物(CMPs)骨架中的孔和极性基团对聚合物的气体吸附性能起着重要作用。阐明聚合物中极性基团的效果对该领域的进一步发展是必不可少的。为了解决这个根本问题,我们使用最简单的芳香系统-苯作为建筑单体,构筑了两个新颖的富羧酸基团的CMPs(CMP-COOH@1,CMP-COOH@2),并探讨了CMPs中游离羧酸基团的量对其孔隙、吸附焓、气体吸附和选择性的深远影响。CMP-COOH@1和CMP-COOH@2显示的BET比表面积分别为835和765 m~2?g~(-1)。这两种聚合物在二氧化碳存储方面显示了高潜力。在273 K和1.05×10~5 Pa条件下,CMP-COOH@1和CMP-COOH@2的CO_2吸附值分别为2.17和2.63 mmol?g~(-1)。我们的研究结果表明,在相同的条件下增加聚合物中羧基基团的含量可以提高材料对气体的吸附容量和选择性。     

密胺苯二醛多孔聚合物/聚二甲基硅氧烷混合基质膜的制备及气体分离性能

以溶液复合成膜法制备了密胺苯二醛多孔聚合物(MA)/聚二甲基硅氧烷(PDMS)混合基质膜,利用扫描电镜(SEM)表征了混合基质膜的形貌。考察了不同MA用量下MA/PDMS混合基质膜的气体分离性能,结果表明,MA的加入可以在提高PDMS膜渗透系数的同时提高CO_2气体分离选择性;随着混合基质膜中MA含量的增加,混合基质膜的渗透系数均明显提高,气体分离选择性则先增大后减小。双组分混合气体分离测试结果表明,MA/PDMS(1.2%(w,质量分数))混合基质膜对CO_2/N_2和CO_2/CH_4的分离选择性分别是19.2和6.0,CO_2的渗透系数达到8100Barrer,均高于纯PDMS膜。MA/PDMS(1.2%(w))混合基质膜对CO_2/N_2混合气的分离性能突破了Robeson上限。     

Molecular simulations of physical aging in polymer membrane materials

Poly(1-trimethylsilyl-1-propyne) (PTMSP), the most permeable polymer known, undergoes rapid physical aging. The permeability of PTMSP to gases and vapors decreases dramatically with physical aging. Cavity size (free volume) distributions were calculated in as-cast and aged PTMSP, using an energetic based cavity-sizing algorithm. The large cavities found in as-cast PTMSP disappear in aged PTMSP, which is consistent with the positron annihilation lifetime spectroscopy (PALS) measurements. We also characterized the connectivity of cavities in both as-cast and aged PTMSP membranes. Cavities are more connected in as-cast PTMSP than in aged PTMSP. The average cavity sizes calculated from computer simulation are in good agreement with PALS measurements. The transport and sorption properties of gases in as-cast and aged PTMSP are also measured by molecular simulation. Computer simulations showed the decrease of permeability and the increase of permeability selectivity in PTMSP membranes with physical aging, which agrees with experimental observations. The reduction in gas permeability with physical aging results mainly from the decrease of diffusion coefficients. Solubility coefficients show no significant changes with physical aging.     

Long-term permeation properties of poly(1-trimethylsilyl-1-propyne) membranes in hydrocarbon—Vapor environment

Poly(1-trimethylsilyl-1-propyne) (PTMSP), a high free-volume glassy di-substituted polyacetylene, has the highest gas permeabilities of all known polymers. The high gas permeabilities in PTMSP result from its very high excess free volume and connectivity of free volume elements. Permeability coefficients of permanent gases in PTMSP decrease dramatically over time due to loss of excess free volume. The effects of aging on gas permeability and selectivity of PTMSP membranes continuously exposed to a 2 mol % n-butane/98 mol % hydrogen mixture over a period of 47 days are reported. The permeation properties of PTMSP membranes are quite stable when the polymer is continuously exposed to a gas mixture containing a highly sorbing organic vapor such af n-butane. The n-butane/hydrogen selectivity was essentially constant for the 47-day test period at a value of 29, or 88% of the initial value of the as-cast film of 33. Condensable gases such as n-butane may serve as a “filler” in the nonequilibrium free volume of the polymer, thereby preserving the high level of excess free volume. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 35 : 1483–1490, 1997     

Gas permeability and stability of poly(1-trimethylsilyl-1-propyne-co-1-phenyl-1-propyne) membranes

A significant reduction in the gas permeability of the poly(1-trimethylsilyl-1-propyne) (PMSP) membrane was investigated in terms of the membrane thickness and the storage environment. The effects of physical aging were observed with thinner membranes and under vacuum conditions compared with storage in air. The decrease in the permeability coefficient was dependent on the decrease in the hole saturation constant of Langmuir adsorption (C'_H), which is related to the volume of the microvoids. Physical aging in the PMSP membrane affected not only the glassy domain but also the rubbery one. To stabilize the permeability of the PMSP membrane, a poly(1-trimethylsilyl-1-propyne-co-1-phenyl-1-propyne) [poly(TMSP-co-PP)] membrane was prepared. Poly(TMSP-co-PP) has the same unit of poly(1-phenyl-1-propyne), which membrane has stable permeability. The poly(TMSP-co-PP) with less than 20 mol % PP content was estimated to be a random copolymer based on theoretical gas permeation analysis. In the poly(TMSP-co-PP) membrane, the relation between the PP content and C'_H was similar to the relation between the PP content and the gas permeability. The stability of the permeability was dependent on the PP content. The poly(TMSP-co-PP) membrane containing 10 mol % PP had both high permeability and good stability under some of the aging conditions performed in this work. © 1995 John Wiley & Sons, Inc.     

Crosslinking poly[1-(trimethylsilyl)-1-propyne] and its effect on physical stability

Poly[1-(trimethylsilyl)-1-propyne] (PTMSP) has been crosslinked using 3,3′-diazidodiphenylsulfone to improve its solvent resistance and physical stability. This study reports the influence of crosslinking on N₂, O₂ and CH₄ gas permeabilities and fractional free volume (FFV) as a function of time. Crosslinking PTMSP renders it insoluble even in excellent solvents for the uncrosslinked polymer. The gas permeability and FFV of uncrosslinked and crosslinked PTMSP decreased over time, so crosslinking PTMSP does not arrest physical aging. The addition of 10 wt.% polysiloxysilsesquioxanes (POSS) nanoparticles decreased the permeability of PTMSP by 55%, and the permeability and FFV values were stable over time for PTMSP films containing 10 wt.% POSS nanoparticles. The permeability of PTMSP at a given FFV was greater than that of other substituted polyacetylenes, polysulfones or polycarbonates, which is consistent with differences in the arrangement of free volume in these polymers, as probed by positron annihilation lifetime spectroscopy (PALS). Ellipsometry was used to characterize physical aging of thin (400 nm) uncrosslinked and crosslinked PTMSP films supported on silicon wafers. The ellipsometry results showed that crosslinking does not markedly slow physical aging of thin PTMSP films.     

Impact of thermal ageing on sorption and diffusion properties of PTMSP

Gas and vapour permeability in both freshly cast and aged poly(1-trimethylsilyl-1-propyne) (PTMSP) membranes were investigated in terms of solubility and diffusion coefficients for two probe molecules, a permanent gas (nitrogen) and an organic vapour (dichloromethane). To get reliable data for this study, we set up a fast and reproducible ageing procedure consisting of thermal treatment of the polymer films (100 °C during 24 h under vacuum). As expected, measurements recorded from time-lag experiments and isothermal sorption showed strong variations of the PTMSP transport properties before and after the thermal ageing procedure. Freshly cast membranes exhibited high permeability, whereas after ageing a 40–45% decrease of the permeability was recorded for both probes. The results demonstrated that only the glassy physical microstructure of PTMSP was affected by the ageing procedure, while the chemical structure was unchanged. Based on a dual-mode model for sorption and a Long's model for diffusion, the analysis of the data showed that the solubility and diffusion coefficients of the gas and the vapour were not affected in the same way. For nitrogen, only the diffusion coefficient decreased, whereas for dichloromethane, the thermal treatment mainly influenced the sorption coefficient. The lower permeability due to the combination of sorption and diffusion parameters could be attributed to a change of the PTMSP hole geometry or the hole connections.     

Membranes for gas separation based on poly(1-trimethylsilyl-1-propyne)–silica nanocomposites

Nanocomposite membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) and silica were synthesized by sol–gel copolymerization of tetraethoxysilane (TEOS) with different organoalkoxysilanes in tetrahydrofuran solutions of PTMSP. The influence of the synthesis parameters (type and concentration of organoalkoxysilanes, temperature and time) on the silica conversion and the gas permeation performance of PTMSP–silica nanocomposite membranes was investigated and discussed in this paper. The nanocomposite membranes were characterized by single and mixed gas permeation, thermogravimetric analysis and scanning electron microscopy. The butane permeability and the butane/methane selectivity increased simultaneously when high silica conversion was obtained and the size of particle was in the range 20–40 nm. For the sake of comparison, nanocomposite membranes based on PTMSP were also prepared by dispersing silica particles with different functional groups into the PTMSP casting solution. The addition of fillers to the polymer matrix can be performed up to a higher content of silica (30% silica-filled PTMSP in contrast to 6 wt.% for the in situ-generated silica). In this case, the simultaneous increase in butane permeability and butane/methane selectivity was significantly higher when compared to the nanocomposite membranes prepared by sol–gel process. The addition of fillers with 50% of surface modification with hydrophobic groups (Si–C₈H₁₇ and Si–C₁₆H₃₃) seems not to lead to a significant increase of the butane/methane selectivity and butane permeability when compared to the silica with hydrophilic surface groups, probably because of the unfavorable polymer/filler interaction, leading to an agglomeration of the long n-alkyl groups at the surface of the polymer. An increase of butane permeability up to six-fold of unfilled polymer was obtained.     

Effect of physical aging of poly(1‐trimethylsilyl‐1‐propyne) films synthesized with TaCl5 and NbCl5 on gas permeability,fractional free volume,and positron annihilation lifetime spectroscopy parameters

The effect of physical aging on the gas permeability, fractional free volume (FFV), and positron annihilation lifetime spectroscopy (PALS) parameters of dense, isotropic poly(1‐trimethylsilyl‐1‐propyne) (PTMSP) films synthesized with TaCl₅ and NbCl₅ was characterized. As‐cast films were soaked in methanol until an equilibrium amount of methanol was absorbed by the polymer. When the films were removed from methanol, film thickness initially decreased rapidly and was almost constant after 70 h in air for both catalysts. This timescale was much longer than the timescale for complete methanol desorption (ca. 5 h). From the film‐thickness data, the reduction in FFV with time was estimated. For samples prepared with either catalyst, the kinetics of FFV reduction were well‐described by a simple model based on the notion either that free‐volume elements diffuse to the surface of the polymer film and are subsequently eliminated from the sample or that lattice contraction controls polymer densification. Methane permeability decreased rapidly during the first 70 h, which was the same timescale for the thickness change. The decrease in methane permeability was smaller in films prepared with NbCl₅ than with TaCl₅. The logarithm of methane permeability decreased linearly as reciprocal FFV increased, in accordance with free‐volume theory. The PALS results indicate that the concentration of larger free‐volume elements (as indicated by the intensity I₄) decreased with aging time and that the other PALS parameters were not strongly influenced by aging. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 1222–1239, 2000     

聚三甲硅基丙炔的紫外辐照研究I．聚三甲硅基丙炔均质膜在空气中的紫外辐照

聚１－三甲硅基丙炔膜经紫外线辐照后其氧氮选择性提高，用ＸＰＳ及水接触角法研究了膜的表面组成对透气性的影响。     

Cross-linking of poly[1-(trimethylsilyl)-1-propyne] membranes using bis(aryl azides)

Cross-linkable poly[1-(trimethylsilyl)-1-propyne] (PTMSP) films were cast from toluene solutions containing PTMSP and either 4,4′-diazidobenzophenone or 4,4′-(hexafluoroisopropylidene)diphenyl azide. The composite films were clear and homogeneous and were cross-linked by UV irradiation at room temperature or thermal annealing at 180°C. Low levels of the bis(aryl azide) (1–5 wt %) were effective in rendering the films insoluble in toluene and THF, both good solvents for PTMSP. The process is simple and effective, and thus PTMSP can be readily converted to mechanically stable membranes with permeabilities and separation factors comparable or higher than those of poly(dimethylsiloxane). The films were characterized by measuring their density, their permeability toward O₂ and N₂, and their spectroscopic properties. Compared to PTMSP, films containing bis(aryl azide) cross-linkers had lower permeabilities and higher separation factors, consistent with a reduction in free volume. When the films were cross-linked photochemically, the permeabilities declined further and the separation factor increased. Films cross-linked thermally had permeabilities comparable to their PTMSP/azide precursors, and density and swelling measurements suggest that higher free volumes are obtained in thermally cross-linked films. All films stored in air suffered from a slow decline in permeability which may reflect slow surface oxidation of the films. When stored in vacuum, cross-linked films were stable and showed no loss in permeability, but the permeability of uncross-linked PTMSP films stored under the same conditions fell to 70% of their original value in 1 month. We attribute the permeability decline to densification accelerated by impurities and solvents. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 959–968, 1998     

Transport of organic vapors through poly(1-trimethylsilyl-1-propyne)

Poly(1-trimethylsilyl-1-propyne) [PTMSP], a high-free-volume glassy polymer, has the highest gas permeability of any known synthetic polymer. In contrast to conventional, low-free-volume, glassy polymers, PTMSP is more permeable to large, condensable organic vapors than to permanent gases. The organic-vapor/permanent-gas selectivity of PTMSP based on pure gas measurements is low. In organic-vapor/permanent-gas mixtures, however, the selectivity of PTMSP is much higher because the permeability of the permanent gas is reduced dramatically by the presence of the organic vapor. For example, in n-butane/methane mixtures, as little as 2 mol% n-butane (relative n-butane pressure 0.16) lowers the methane permeability 10-fold from the pure methane permeability. The result is that PTMSP shows a mixed-gas n-butane/methane selectivity of 30. This selectivity is the highest ever observed for this mixture and is completely unexpected for a glassy polymer. In addition, the gas mixture n-butane permeability of PTMSP is considerably higher than that of any known polymer, including polydimethylsiloxane, the most vapor-permeable rubber known. PTMSP also shows high mixed-gas selectivities and vapor permeabilities for the separation of chlorofluorocarbons from nitrogen. The unusual vapor permeation properties of PTMSP result from its very high free volume - more than 20% of the total volume of the material. The free volume elements appear to be connected, forming the equivalent of a finely microporous material. The large amount of condensable organic vapor sorbed into this finely porous structure causes partial blocking of the small free-volume elements, reducing the permeabilities of the noncondensable permanent gases from their pure gas values.