CO2-permselective membranes of crosslinked poly(vinyl ether)s bearing oxyethylene chains

Cationic copolymerizations of vinyl ether monomers having a triethylene glycol segment [2-(2-(2-methoxyethoxy)ethoxy)ethyl vinyl ether (TEGMVE)] with vinyl ether monomer having a methacrylate unit [2-(2-vinyloxyethoxy)ethyl methacrylate: VEEM] were performed to obtain crosslinkable copolymers [poly(TEGMVE-VEEM)] with different composition rates. Methacrylate groups in poly(TEGMVE-VEEM)s partially reacted to give crosslinked polymer membranes. The free-standing membranes of poly(TEGMVE-VEEM)s obtained at monomer feed ratios of 6:1, 10:1, and 14:1 were too brittle, while their composite membranes with PTFE sheet were tough enough to measure gas permeability. All the membranes of poly(TEGMVE-VEEM) showed high CO₂/N₂ selectivity (PCO₂/PN₂$P_{{\text{CO}}_2}/P_{{\text{N}}_2}$ = 35–54) because of their high CO₂ solubility selectivity (SCO₂$S_{{\text{CO}}_2}$/SN₂$S_{{\text{N}}_2}$ = 38–61). The gas permeability increased as the composition ratio of VEEM decreased, and the composite membrane of poly(TEGMVE-VEEM)(14:1) showed the highest CO₂ permeability (PCO₂$P_{{\text{CO}}_2}$ = 410 barrers) among the present polymer membranes.     

Synthesis and gas permeability of nitrated and aminated Poly(diphenylacetylene)s

Poly(diphenylacetylene) [PDPA] derivatives were nitrated using a mixture of nitric acid and sulfuric acid. Nitration of poly[1-(p-trimethylsilyl)phenyl-2-phenylacetylene] (1a) proceeded, and the nitro groups were substituted to trimethylsilyl groups on benzene rings. The degree of nitration (DN) increased with reaction time, and it reached 0.41 for 3.0 h. Fluorine-containing PDPA (1b and 1c) showed less reactivity for nitration, and the DNs were only 0.18 and 0.06, respectively, under the same conditions. Nitration of PDPAs having n-butyl and t-butyl groups (1d and 1e) afforded the nitrated PDPAs, whose DN were 0.20 and 0.14, respectively. Reduction of nitro groups on PDPAs proceeded quantitatively to produce the corresponding PDPAs possessing amino groups (3a-e). Aminated PDPAs exhibited high CO₂ permselectivity compared to the corresponding non-aminated PDPAs. The CO₂ permeability coefficients of aminated PDPAs (3a-d) were lower than those of the corresponding polymers (1a-d) because the polymer chain packing was strengthened by the intermolecular interaction between polar amino groups, but t-butyl group-containing aminated PDPA (3e) showed high CO₂ permeability than 1e because the chain packing was weakened by the steric repulsion of bulky t-butyl groups.     

Poly(vinyl chloride) (PVC) hollow fibre membranes for gas separation

Poly(vinyl chloride) (PVC) gas separation hollow fibre membranes were produced from multicomponent dopes using dry/wet forced convection spinning. Membranes spun from a low polymer content solution exhibited disappointing gas separation properties. Their low selectivities were indicative of thick skins and high surface porosities. In contrast, high polymer content spun fibres showed good gas separation properties. Selectivities were high, active layers relatively thin and surface porosities moderate. Coating with poly(dimethylsiloxane) nullified the surface pores. The favourable performance of the high polymer content spun fibres was also related to shear rate and forced convection residence time during spinning. To the knowledge of the authors, this work represents the first reported success in producing PVC hollow fibre membranes with morphologies suitable for gas separation. The development of PVC hollow fibres relates to the ultimate quest to produce membranes capable of reliably separating oxygen and ozone gas mixtures.     

New syntheses of methoxypoly(oxyethylene) vinyl ether and its oligo analog

Summary A new method to synthesize vinyl ethers of methoxyoligooxyethylene, I, and methoxypoly(oxyethylene), II, is described. In this work, these derivatives were prepared by reacting the alkoxide of ethylene glycol vinyl ether with the tosylate (or mesylate) of oligo-/or methoxypoly(oxyethylene) in tetrahydrofuran. Received: 27 November 2001/Revised version: 13 March 2002/ Accepted: 18 March 2002     

含异氰脲酸酯结构聚醚多元醇的合成

以1,3,5-三羟乙基异氰脲酸酯(THEIC)为引发剂、三氟化硼乙醚络合物为催化剂,环氧化合物为环单体,进行了阳离子开环聚合反应的研究.发现THEIC与环氧单体可在非均相体系中平稳地进行阳离子开环聚合反应.在THEIC体系,就链引发而言,环氧氯丙烷的大于环氧丙烷、丁基醚环氧乙烷.调整环单体加料次序就可以获得嵌段共聚醚多元醇.     

聚(芳基醚1,3,4-噁二唑)类聚合物的磺化及表征

为了探索影响芳香族聚噁二唑的磺化反应的因素,分别以发烟硫酸和氯磺酸为磺化试剂对几种含醚键聚芳噁二唑(PEODs)进行磺化,研究了以氯磺酸为磺化试剂时磺化反应时间、用量对磺化反应的影响,并分析了PEODs用于质子交换膜的潜在应用.磺化产物的结构与性能通过傅里叶红外(FT-IR)、氢谱(1H-NMR)、离子交换当量、热重分析(TGA)和溶解性等测试进行了表征.结果表明:发烟硫酸磺化产物磺化度不可控制,磺化度较氯磺酸的磺化产物高;采用氯磺酸磺化时,磺化时间对磺化反应没有影响,氯磺酸用量仅对侧苯基双酚A型聚噁二唑有影响;邻叔丁基型聚噁二唑的氯磺酸磺化产物有用于质子交换膜的潜力.     

新型含偶氮结构聚芳醚砜醚酮酮的合成与表征

在无水AlCl3及N-甲基吡咯烷酮(NMP)/1,2-二氯乙烷(DCE)复合溶剂的存在下,将含砜基芳二醚类单体与含偶氮苯结构芳二甲酰氯进行低温付-克缩聚反应,合成了一类新型含偶氮结构聚芳醚砜醚酮酮树脂。用IR、TG、WAXD及元素分析等技术进行了结构表征和性能测试。结果表明:所合成的聚合物树脂具有预期结构且为非晶态聚合物;在N2气氛中质量损失5%的温度(Td)分别为445～463℃;聚合物除了能在浓硫酸、CF3COOH/CHCl3等强极性质子型溶剂中溶解外,还能溶解于N-甲基吡咯烷酮(NMP)、N,N-二甲基甲酰胺(DMF)、二甲基亚砜(DMSO)等强极性非质子型溶剂中,也能在普通溶剂,如氯仿(CHCl3)、1,2-二氯乙烷(DCE)、四氢呋喃(THF)等中溶解。     

Poly(methyl vinyl ether-b-octadecyl vinyl ether): a new non-ionic surfactant

Block copolymers consisting of methyl vinyl ether (MeVE) units and octadecyl vinyl ether (ODVE) units were synthesized using the cationic living polymerization technique. The polymerization of MeVE was initiated with the trimethyl silyl iodide/1,1-diethoxyethane/ZnI₂ system at −40°C in toluene and the living polymer thus obtained was used as initiator for the polymerization of ODVE at 07deg;C. The combination of hydrophilic (PMeVE) and hydrophobic (PODVE) segments provides the block copolymers with non-ionic surfactant properties, which have been evaluated by measurement of the stabilities of water–decane emulsions.     

Poly(vinyl alcohol) nanocomposite films: Thermooptical properties,morphology, and gas permeability

Poly(vinyl alcohol) (PVA)/saponite nanocomposites were prepared with various clay concentrations with the solution intercalation method. The intercalations of the polymer chains in the clay were examined with wide‐angle X‐ray diffraction and transmission electron microscopy. The variations of the dispersion, morphology, thermal properties, and gas permeability of the nanocomposites with clay concentrations in the range of 0–10 wt % were examined. Up to a 5 wt % clay loading, the clay particles were highly dispersed in the PVA matrix without any agglomeration of particles. However, some agglomerated structures formed in the polymer matrix above a 7 wt % clay concentration. The thermal stability of the hybrids increased linearly with increases in the clay loading up to 10 wt %. To measure the oxygen permeability and optical properties of the PVA hybrid films, the PVA hybrid solutions were coated onto both biaxially oriented polypropylene and poly(ethylene terephthalate) films, which were used as polymer substrates. The oxygen permeability values monotonically decreased with increases in the clay loading in the range of 0–10 wt %. The optical properties, such as the haze and gloss of the hybrid films when coated onto the matrix films, were nearly constant, that is, independent of the clay loading. These improvements arose because of the largely nanometer‐scale dispersion of the clay layers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 591–596, 2006     

Synthesis and permeability properties of crosslinkable elastomeric poly(vinyl allyl dimethylsilane)s

This article presents the results of a systematic synthesis study of elastomeric crosslinkable polysilicon olefins, the related thermal crosslinking kinetics, and the main permeability parameters recorded for inorganic gases (He, N₂, O₂, and CO₂) and C₁–C₇ hydrocarbons. Poly(vinyl allyl dimethylsilane) (PVADMS; glass‐transition temperature < 273°K) was obtained by the anionic polymerization of bifunctional vinyl allyl dimethylsilane monomer. The polymers were amorphous, high molecular compounds with mixed carbo‐heterochain structures containing double bonds capable of intermolecular crosslinking under a thermal treatment. Thus, thermally crosslinked polymers exhibited a high resistance toward exposure to organic vapors, unlike noncrosslinked PVADMS. IR spectroscopy was used to investigate the polymer structural changes induced by the thermal treatment. An original technique based on a differential method was used to measure gas permeability during thermal crosslinking. PVADMS possessed higher permeability for C₁–C₇ hydrocarbons than for inorganic gases (excluding CO₂), even after crosslinking. Permeability coefficients ranging from 140 to 1780 Barrer for He and CH₄ were found before crosslinking; the thermal crosslinking induced a nonlinear permeability decrease that could be correlated with the disappearance of the double bonds in the polymer structures, that is, cis‐CH?CH? , trans‐CH?CH? , and CH₂?CH? in the side‐chain position. According to the found properties, PVADMS could be used as a prospective material for the preparation of highly permeable selective membranes suitable for lower hydrocarbon and volatile organic compound recovery from various chemical and petrochemical process streams. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 927–935, 2005     

乙酰乙酰化聚乙烯醇的合成

通过酯交换反应将乙酰乙酰基引入聚乙烯醇(PVA),并采用红外光谱对产物进行了表征。重点讨论了反应温度、反应时间、乙酰乙酸酯用量等因素对酯交换反应的影响。试验发现:随乙酰乙酸酯用量的增加,乙酰乙酰化程度逐渐增大;随反应温度的升高,乙酰乙酰化程度先逐渐提高,后趋于稳定;随反应时间的延长,乙酰乙酰化程度提高,2.5h后趋于平衡。     

Poly(vinyl alcohol) and poly(vinyl amine) blend membranes for isopropanol dehydration

Blended membranes of hydrophilic polymers poly(vinyl alcohol) (PVA) and poly(vinyl amine) (PVAm) were prepared and crosslinked with glutaraldehyde. The prepared membranes were characterized using infrared (attenuated total reflection mode) spectroscopy, differential scanning calorimetry, X‐ray diffractometry, and scanning electron microscopy measurements. Pervaporation performances of the membranes were evaluated for the separation of water‐isopropanol (IPA) mixtures. As the PVAm content increased from PVAm0 to PVAm1.5, the flux through a 70 μm film increased from 0.023 to 0.10 kg/m² h at an IPA/water feed ratio of 85/15 at 30 °C. The driving force for permeation of water increased due to the temperature but it has no effect on IPA permeation. Activation energies for the permeation of IPA and water were calculated to be 17.11 and 12.46 kJ/mol, respectively. Controlling the thickness of the blend membrane could improve the permeation flux with only a marginal reduction in the separation factor. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45572.     

Poly(ether ketone azomethane)s and poly(ether ketone imide)s containing naphthylene moieties

A new diamine monomer, 1,5-bis[4-(4-aminophenoxy)]benzoyl-2,6-dimethoxynaphthalene, was synthesized via a Friedel–Crafts acylation reaction followed by an aromatic nucleophilic substitution reaction. Six ether–ketone linked polymers, named as poly(ether ketone azomethane)s and poly(ether ketone imide)s, were successfully prepared through the polycondensations of the diamine monomer with dialdehydes and dianhydrides, respectively. These naphthylated polymers exhibited high T _g values (142–288 °C), due to their bulky and rigid chemical structure. Meanwhile, they showed good thermal stability and improved solubility. Typically, some of them were casted into thin flexible film and showed high moduli.     

Synthesis of poly(vinyl alcohol)s with narrow molecular weight distribution from poly(benzyl vinyl ether) precursors

Summary A series of poly(benzyl vinyl ether)s of low molecular weight (5000 to 15000 g mol^-1) and narrow molecular distribution ( ) have been synthesisedvia the cationic polymerisation of benzyl vinyl ether. Acetylation with acetic anhydride/tin (IV) chloride leads to poly(vinyl acetate), which can be hydrolysed to near-monodisperse water-soluble poly(vinyl alcohol) with an isotacticity of approximately 47%. This polymer was re-acetylated and its molecular weight distribution assessed to confirm that hydrolysis gives minimal chain scission.     

Synthesis of Poly(arylene ether ketone)s containing Unsymmetrical Pyridyl Ether Linkages

Summary New high molecular weight poly(arylene ether ketone)s were prepared from pyridine containing unsymmetrical dichloro monomers. Incorporation of unsymmetrical pyridyl ether linkages instead of phenylene ether linkages reduces the high crystallinity of parent poly(arylene ether ketone)s and provides enhanced solubility. Replacement of a single atom in the repeating units of polymers can efficiently change the physical properties of the resulting polymers. The pyridyl ether containing poly(arylene ether ketone)s showed outstanding thermal stability (T_d5>470 °C).     

Methylated and Trifluoromethylated Aromatic Poly(ether sulfone)s

Summary Four aromatic poly(ether sulfone)s (PESs) based on (3-niethyl)phenylhydroquinone. (3-trifluoromethyl)plienylhydroquinone, (3,5-dimethyl)phenyIhydroquinone, and (3,5-ditrifluoromethyl)phenylhydroquinone were prepared via a nucleophilic aromatic substitution polycondensation with bis(4-fluorophenyl) sulfone. These PESs had a high thermal stability with a 5% weight loss above 423 °C in N₂. The PESs possessed good solubility in common organic solvents. All the polymers formed transparent and flexible films using solution casting method. The dielectric constants estimated from refractive indices of the PES films are 2.64-3.07. Compared with the corresponding methylated PESs, the trifluoromethylated PESs exhibited low glass transition temperatures, higher thermal decomposition temperatures, and low dielectric constants.     

Poly(aryl ether ketone)s with bromomethyl groups: Synthesis and quaternary amination

A series of bromomethylated poly(arylene ether ketone)s (PAEKs) with different contents of bromine tethered to the benzyl groups were successfully synthesized and characterized in this work. For this purpose, poly(arylene ether ketone) with 3,3′,5,5′‐tetramethyl‐4,4′‐dihydroxybipheny moiety (PAEK‐TM) was prepared by the aromatic nucleophilic polycondensation, and then the PAEK‐TM has benzylic methyl groups that were converted to bromomethyl groups by a radical reaction using N‐bromosuccinimide. Then, the bromomethylbenzyl groups in the membrane was converted to quaternary ammonium moieties in TMPAEK‐NOH. ¹H‐NMR measurements were used to characterize and confirm the structures of the resulting PAEK‐x‐BrTM and TMPAEK‐NBr derivatives (x refers to the molar percentage of bromine introduced per repeating units). TGA analysis showed that PAEK‐x‐BrTM exhibited a very low‐decomposition temperature at about 200°C corresponding to the C Br bond cleavage. The hydroxide conductivity of TMPAEK‐NOH membrane was 8 mS cm⁻¹ at room temperature, while the water uptake of TMPAEK‐NOH membrane was 22.3% at 20°C and 32.6% at 60°C. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Phase transition of thermosensitive amphiphilic cellulose esters bearing olig(oxyethylene)s

Summary A series of cellulose esters bearing olig(oxyethylene)s with different degree of substitution (DS) and different length of the oxyethylene chain were synthesized by a homogeneous reaction of cellulose with corresponding monofunctional acid chloride in a 10% LiCl-dimethyl acetoamide (DMAc) solution. The effect of total DS value on the solubility of the derivatives in aqueous solution was investigated. It was found that the lower limit DS value for both water-soluble and amphiphilic derivatives decreases with increasing length of oxyethylene chains. The amphiphilic derivatives, which are soluble in both water and chloroform, precipitate out of aqueous solution on heating without gel forming, such a phase transition behavior was studied in terms of DS value, length of oxyethylene and concentration. The precipitation temperature (T_p) of the amphiphilic derivatives is range from 54°C to 96°C. It decreases with increasing the total DS value, and increases with an increase in the length of oxyethylene chains. The T_p value of the derivatives was found to be almost independent in the concentration range of 1–15 wt %, however the T_p value increases sharply with decreasing polymer concentration when the concentration is lower than 1 wt%. Received: 29 August 2000/Revised version: 16 October 2000/Accepted: 31 October 2000     

Non-equilibrium electrolyte permeability in poly(vinyl alcohol) membranes

Permeability of poly(vinyl alcohol) membranes was studied as a function of exposure time in 45% aqueous potassium hydroxide and quantity of residual water in film. The presence of non-equilibrium and equilibrium periods in electrolyte permeability of PVA films containing aqueous KOH solution or residual water were found and were explained from the viewpoint of change in the diffusion mechanism of permeability. The influence of cross-linking on permeability of PVA films was examined.     

Synthesis of hydrophilic poly(vinyl ether)s and their application for separation media design

Poly(2-acetoxyethyl vinyl ether (AcOVE)) and poly(2-acetoxyethyl vinyl ether-co-2-vinyloxyethyl phthalimide) were synthesized by traditional cationic polymerization, typically at −20°C in toluene with BF₃O(C₂H₅)₂ as initiator, to give polymers with degrees of polymerization (Dp) in the range of 600–1100. In addition, poly(AcOVE) was polymerized by controlled cationic polymerization at 0°C with molecular weights in a predetermined fashion. The Dp's were calculated from Dp = [M]₀/[I]₀ and typical values were 5, 10, 100 and 200. The molecular weight values obtained for a theoretical Dp = 200, were for poly(2-acetoxyethyl vinyl ether), M_n = 19,200, M_w = 22,700 and POLYDISPERSITY = 1.2, as determined by GPC. The deprotected hydrophilic polymers, poly(2-hydroxyethyl vinyl ether) and poly(2-hydroxyethyl vinyl ether-co-2-aminoethyl vinyl ether), were used for the preparation of novel gel filtration media as well as new anion exchangers. In the case of gel filtration, poly(2-hydroxyethyl vinyl ether) was attached to a beaded agarose matrix (34 μm), i.e. Sepharose® HP. It was shown that the attachment of the poly(vinyl ether) affected the selectivity. In gel filtration of selected biomolecules, the poly(vinyl ether) modified agarose matrix showed performance characteristics comparable to the reference used, i.e. Superdex® 30 prep grade. In addition the poly(vinyl ether)s were shown to be stable in a wide pH-range. The stability was confirmed by the conclusion that no changes in molecular weight were observed after treatment with 0.1 M HCl (pH = 1) or 0.01 M NaOH (pH = 12) for six weeks at 40°C. For the preparation of anion-exchanger media, the beads containing poly(2-hydroxyethyl vinyl ether) was further modified with a quaternary ammonium group, to produce a separation media having a high dynamic binding capacity for bovine serum albumin (BSA).