Intermediate thermal manipulation of polymers of intrinsic microporous (PIMs) membranes for gas separations

The high fractional free volume (FFV) endowed polymers of intrinsic microporosity (PIMs) with high gas permeability but low selectivity. Herein, an intermediate temperature range was deliberately utilized to tune PIM-1 membrane microstructure in nitrogen atmosphere to enhance gas separation performance. During intermediate thermal manipulation, the synergistic effects of thermal-induced cross-linking and decomposition on PIM-1 membranes have optimized the micropores for significantly increasing membrane molecular-sieving ability with the boosted selectivity of 350 (H₂/N₂), 1,472 (H₂/CH₄), 3,774 (H₂/C₃H₈), and 197 (CO₂/CH₄) respectively, with the H₂ permeability of 234 Barrer, correspondingly, surpassing the “Robeson's Upper Bound”. The facile strategy simultaneously utilizing the thermal-induced cross-linking and decomposition, might provide a new platform to develop the high-performance membranes for highly-efficient hydrogen purification and CO₂ separations.     

Phthalimide based polymers of intrinsic microporosity

A series of phthalimide based microporous polymers were successfully prepared by conventional nucleophilic substitution reaction of several newly synthesized fluoro-monomers with commercially available 5,5′,6,6′-tetrahydroxy-3,3,3′,3′-tetramethylspirobisindane. FTIR, ¹H NMR, and elemental analyses were used to identify the proposed structures of the polymers. The synthesized polymers are of high molecular weight as demonstrated by Gel Permeation Chromatography (GPC). Thermogravimetric analysis shows that the prepared polymers were stable up to 300 °C. From the porosity analysis it is clear that the prepared polymers are analogous to polymers of intrinsic microporosity (PIMs) with high surface area (500–900 m²/g). The t-plot analysis shown that the major contribution to the specific surface area is arising from the micropore surface area with narrow size distribution of ultramicropores as confirmed by the Horvath-Kawazoe (H-K) analysis. The hydrogen storage capacity of the prepared PIM-R(1–7) and CO-PIM(3,4,6,7) were promising (up to 1.26 wt%, 77 K, at 1.13 bar) with high isoteric heats of H₂ adsorption (8.5 kJ/mol).The results of this study demonstrate that controlling the appropriate monomer content via the three-dimensional structure can provide a uniform microporous morphology in the target polymers.     

Centrotriindane- and triptindane-based polymers of intrinsic microporosity

In this paper we describe the synthesis and physical characterisation of polymers derived from hydroxyl containing bowl-shaped “centrotriindane” and propellane-type “triptindane” monomers using the dibenzodioxin-forming polymerisation reaction with 2,3,5,6-tetrafluoroterephthalonitrile. Evaluation of the microporosity of the resulting polymers via nitrogen adsorption measurements revealed apparent Brunauer-Emmett-Teller (BET) surface areas in the range of 555–1039 m² g⁻¹ which can be related to the distinct shape of the monomeric units. An evaluation of the shape of the monomers, using X-ray crystallography, helps to explain the degree of microporosity of the polymers from which they are made.     

Polymers based on methyl acrylamidoglycolate methyl ether (MAGME): Michael addition-amidation reactions

Summary Polymers were synthesized from methyl acrylamidoglycolate methyl ether (MAGME) and various primary amines by utilizing MAGME's electron poor double bond and activated ester functionalities. Generally, the polymerizations proceeded to relatively high conversions but the polymers produced had only low to moderate inherent viscosities and low Tg's. Spectroscopy (IR and H-NMR) showed that the polymers had the structure expected from a consideration of the chemistry involved.     

Synthesis and characterization of fluoropolymers with intrinsic microporosity and their hydrogen adsorption studies

Microporous polymers with rigid organic architecture offer a wide range of efficient on board hydrogen storage at low temperature. The fluoropolymers with intrinsic microporosity (MP1 and MP2) were synthesized and characterized. Characterization technique such as high resolution transmission electron microscopy (HRTEM) revealed that the highly stable microporous structure of MP2 was composed of nanoporous frame work which was further supported by the computational study. The high surface area and microporosity of the polymers were estimated by measuring the N₂ gas adsorption. The MP1 and MP2 exhibit BET surface areas 666 and 1050 m²/g respectively. The micropore size distribution curves show a higher concentration of subnanometer pores. The hydrogen storage capacity of the prepared polymers are promising and the performance relative to other microporous polymers is comparable. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Polymers and copolymers based on vinyl tetrazoles, 2. Alkylation of poly(5-vinyl tetrazole)

Alkylation of poly(5-vinyl tetrazole) with dimethyl sulfate and tert-butyl alcohol as well as with alkyl halides RHal (R?CH₃, C₂H₅, CH₂? CH?CH₂, n-C₄H₉, t-C₄H₉) has been studied under various conditions in order to develop a new method of synthesis of tetrazole-containing polymers having a complex of valuable properties. The kinetic study of the process and comparison of isomeric compositions and spectroscopic characteristics (IR, ¹H NMR and ¹³C NMR) of poly(N-alkyl-5-vinyl tetrazole)s synthesized by alkylation of poly(5-vinyl tetrazole) and of those prepared by (co)polymerization of the corresponding vinyl tetrazoles have been carried out. The alkylation is found to proceed to high conversion extents (up to 99.8%) and enables to obtain a wide variety of polymeric products having the composition, structure and properties very similar to those of homo- and copolymers.     

Highly permeable reverse osmosis membranes incorporated with hydrophilic polymers of intrinsic microporosity via interfacial polymerization

Enhancing the water permeation while maintaining high salt rejection of existing reverse osmosis (RO) membranes remains a considerable challenge. Herein, we proposed to introduce polymer of intrinsic microporosity, PIM-1, into the selective layer of reverse osmosis membranes to break the trade-off effect between permeability and selectivity. A water-soluble a-LPIM-1 of low-molecular-weight and hydroxyl terminals was synthesized. These designed characteristics endowed it with high solubility and reactivity. Then it was mixed with m-phenylenediamine and together served as aqueous monomer to react with organic monomer of trimesoyl chloride via interfacial polymerization. The characterization results exhibited that more “nodule” rather than “leaf” structure formed on RO membrane surface, which indicated that the introduction of the high free-volume of a-LPIM-1 with three dimensional twisted and folded structure into the selective layer effectively caused the frustrated packing between polymer chains. In virtue of this effect, even with reduced surface roughness and unchanged layer thickness, the water permeability of prepared reverse osmosis membranes increased 2.1 times to 62.8 L·m^-2·h^-1 with acceptable NaCl rejection of 97.6%. This attempt developed a new strategy to break the trade-off effect faced by traditional polyamide reverse osmosis membranes.     

Post-synthesis amination of polymer of intrinsic microporosity membranes for CO2 separation

Membrane separation is an energy-saving technology for carbon capture. However, it is subjected to permeability-selectivity trade-off limitation. Although chemical functionalization is proposed to boost separation efficiency, controlling sorption–diffusion process remains extremely challenging. In this study, a facile, controllable, and versatile chemical vapor amination strategy is reported to simultaneously tune gas sorption and diffusion in polymer of intrinsic microporosity (PIM)-based membranes for improving carbon capture performance. Through simple exposure in amine vapors under mild conditions, nucleophilic substitution of amines toward ether and halogen groups induce grafting, ring-opening, terminal replacement, chain-scission, and crosslinking of PIM-1, thereby underpinning CO₂-philicity and tailoring passageway. The prepared CO₂-philic membranes exhibit substantially improved CO₂/N₂ selectivity over 30.8, about 226% as that of original one, accompanied by high CO₂ permeability of 2590 Barrer, which can surpass the trade-off upper bound of polymer membranes. Our results reveal that post-synthesis amination is an effective route to obtain high-performance membranes.     

Preparation of polymer of intrinsic microporosity composite membranes and their applications for butanol recovery

We fabricated novel composite membranes composed of a polymer of intrinsic microporosity (PIM-1) and carbon black (CB) nanoparticles functionalized with the silane coupling agent aminopropyl triethoxysilane to recover butanol from aqueous solutions by pervaporation (PV). Scanning electron microscopy showed that the composite membranes were dense and defect free and had good adhesion with substrates. Compared with the those of pristine PIM-1 membranes, the water contact angles of the composite membranes increased from around 86° to more than 90°; this confirmed the improvement of the hydrophobicity. The swelling degree of the 6 wt % CB-filled PIM-1 membranes dropped 23%; this indicated an increase in the swelling resistance. Furthermore, the PV results show experimentally that the incorporation of the functionalized CBs into the PIM-1 matrix considerably improved both the permeability and selectivity to butanol. At a 4 wt % CB content, the optimum separation performance, with a separation factor of 19.7 and a permeation flux of 1116 g m⁻² h⁻¹, was achieved in an aqueous solution containing 5 wt % butanol at 30°C. It was noteworthy that the as-fabricated membranes exhibited a good separation stability. This is a step forward in terms of continuous butanol production with hybrid membranes in fermentation processes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46912.     

Functionalized carbon nanotubes mixed matrix membranes of polymers of intrinsic microporosity for gas separation

ABSTRACT: The present work reports on the gas transport behavior of mixed matrix membranes (MMM) which were prepared from multi-walled carbon nanotubes (MWCNTs) and dispersed within polymers of intrinsic microporosity (PIM)-1 matrix. The MWCNTs were chemically functionalized with poly(ethylene glycol) (PEG) for a better dispersion in the polymer matrix. MMM-incorporating functionalized MWCNTs (f-MWCNTs) were fabricated by dip-coating method using microporous polyacrylonitrile membrane as a support and were characterized for gas separation performance. Gas permeation measurements show that MMM incorporated with pristine or functionalized MWCNTs exhibited improved gas separation performance compared to pure PIM-1. The f-MWCNTs MMM show better performance in terms of permeance and selectivity in comparison to pristine MWCNTs. The gas permeances of the derived MMM are increased to approximately 50% without sacrificing the selectivity at 2 wt.% of f-MWCNTs' loading. The PEG groups on the MWCNTs have strong interaction with CO2 which increases the solubility of polar gas and limit the solubility of nonpolar gas, which is advantageous for CO2/N2 selectivity. The addition of f-MWCNTs inside the polymer matrix also improved the long-term gas transport stability of MMM in comparison with PIM-1. The high permeance, selectivity, and long term stability of the fabricated MMM suggest that the reported approach can be utilized in practical gas separation technology.     

Synthesis of methyl methacrylate oligomers with substituted tetraphenylethane initiator

The radical polymerization of (meth)acrylic monomers (eg methyl methacrylate; MMA) with benzopinacolate‐type initiators has been investigated mainly by Bledzki and Braun. With respect to this work, the typical system (MMA/1,1,2,2‐tetraphenyl‐1,2‐bis(trimethylsiloxy)ethane) has been investigated. The concomitant uses of ¹H NMR and size exclusion chromatography have allowed the percentage of MMA telechelic oligomers present in the medium versus reaction time to be followed. The results show clearly a decrease in the living character of this type of radical polymerization with evolution from telechelic oligomers to monofunctional polymers. In addition, the polymerization features versus reaction time are simulated using the GEAR package; good agreement between the calculated and experimental data is obtained. © 2001 Society of Chemical Industry     

Polymers and copolymers based on vinyl tetrazoles, 1. Synthesis of poly(5-vinyl tetrazole) by polymer-analogous conversion of polyacrylonitrile

Interaction of polyacrylonitrile with sodium azide and ammonium chloride leading to the formation of poly(5-vinyl tetrazole) has been studied in detail. The reaction is found to proceed to high conversion extents (up to 94–94.5%) and allows to obtain polymeric products with a wide range of poly(5-vinyl-tetrazole) content. Comparative studies of the structures and properties of the obtained polymers and 5-vinyl tetrazole homopolymer as well as copolymers of 5-vinyl tetrazole with acrylonitrile have been carried out using IR, ¹³C NMR and complex thermal analysis data.     

A microporosity study of Villamayor Sandstone (Salamanca, Spain)

In the clay fraction (<2 μm) of the Villamayor Sandstone (Salamanca, Spain), pores with a diameter close to 3 nm are predominant. These pores are in the mesoporosity range (2–40 nm) and micropores are absent. The clay fraction is composed mainly of mica and chlorites with small amounts of quartz and feldspars; very little palygorskite or smectite is present. Specific surface area values range from 62 to 78 m² g⁻¹. On heating in vacuo at 470 K no significant change in the pore size distribution was observed, but the specific surface area decreased by ca. 10%, probably due to sintering of the particles on loss of water and surface hydroxyl groups. Treatment with humid nitric oxide for 20 h at this same temperature decreased the contribution by these pores but increased that from pores in the range 5–15 nm diameter. No change was observed, however, in the X-ray diffraction diagram, indicating that changes upon nitric oxide treatment affect isolated, non-periodical portions of the crystals.     

5-(2-氨基-4-氯苯基)四氮唑的合成

4-氯-2-硝基苯甲酸用甲基磺酰胺与五氯化磷氰化,铂炭催化剂存在下加氢还原得2-氨基-4-氯苯甲腈,接着与叠氮化钠成四唑环合成5-(2-氨基-4-氯苯基)四氮唑;以4-氯-2-硝基苯甲酸计,产品总收率70%,含量99%(HPLC法),产品经IR,1HNMR,MS测定,表明结构正确。     

Compatibilization of poly(methyl acrylate) with poly(methyl methacrylate) through charge transfer interactions

Summary Copolymers of methyl acrylate (MA) with an electron-donor comonomer (N-vinylcarbazole) (NVC) are mixed with copolymers of methyl methacrylate (MMA) with a electron-acceptor comonomer (2-(3,5-dinitrobenzoyl) oxyethyl methacrylate) (DNBM) such that 1:1 mol ratios of NVC:DNBM are present at all times. The blends obtained are phase separated up to an average of 27 mol% donor/acceptor structural unit in the copolymer. Above 27 mol% perturbation, poly(MA) and poly(MMA) become compatible.     

Nucleophilic substitution onto poly (methyl methacrylate): 3. Compositional homogeneity of the substituted polymethacrylates

The chemical homogeneity of a series of copolymers obtained by nucleophilic substitution of organolithium reagents RCH₂Li [R = S(C₆H₅), SOCH₃, SO₂CH₃ and SO₂N(CH₃)₂] on a high molecular weight poly(methyl methacrylate) (PMMA, $\text{DP}{}_{\mathrm{n}}\text{= 700}$) has been studied by different methods, over a wide range of substitution degrees ($\text{0.14 ?}\text{DS}{}_{\mathrm{m}}\text{? 0.76}$). ‘Cross’ fractionation is much more efficient than ‘one direction’ fractionation, and it allows the determination of $\text{}\text{?}\text{gs}{}^2$ variance values as low as 2 × 10^?4 with sufficient accuracy. The light scattering method is far less sensitive in this range of low compositional polydispersity, even for a suitable system. The fairly high chemical homogeneity observed for all the copolymers, prepared either in homogeneous or heterogeneous solution, may be correlated with both the high molecular weight of the PMMA precursor and the autoretarded kinetics of the substitution process.     

用于CO2/CH4分离的cPIM-1/ZIF-8混合基质膜的制备

自聚微孔聚合物（PIM-1）虽具有良好的CO₂渗透性能,但其气体选择性普遍较差,限制其在CO₂/CH₄分离领域的应用。本文以N,N-二甲基甲酰胺（DMF）为溶剂制备ZIF-8纳米粒子,将其引入到羧基化的PIM-1基质中,制备了cPIM-1/ZIF-8混合基质膜,用于CO₂/CH₄分离。结果表明：由于合成ZIF-8的溶剂也是cPIM-1的良溶剂,使得两者之间具有良好的界面相容性,从而使ZIF-8添加量高达质量分数45%。随着ZIF-8添加量的增加,膜的CO₂渗透速率持续增加,CO₂/CH₄选择性呈现先上升后下降的趋势。当ZIF-8添加量为质量分数25%时,膜的CO₂/CH₄分离性能最好,即CO₂渗透系数为3942 Barrer,CO₂/CH₄选择性为18.7,较cPIM-1纯膜分别提高了 84%和43%,成功地超越了Robeson分离上限。     

Study of polymer blends of poly(acetylene) with poly(methyl methacrylate) and methyl methacrylate-butadiene-styrene copolymer

Summary Electroactive polymer blends of polyacetylene (PA) with poly (methyl methacrylate) (PMMA) or methyl methacrylate-butadien-styrene (MBS) copolymer were prepared in situ as free-standing films or powders by polymerization of acetylene in the presence of PMMA or MBS-copolymer, using Luttinger's catalyst. Blends of different composition were studied by infrared spectroscopy and electrical conductivity measurements. Environmental stability of pristine and doped PA was improved to some extent in the presence of PMMA.     

Bis(3-aminophenyl)methyl phosphine oxide-based (methyl) nadicimide resins

Ten nadicimide/methyl nadicimide end-capped oligomeric resins were prepared by reacting endo-5-norbornene-2,3-dicarboxylic acid anhydride (methyl nadic anhydride), pyromellitic dianhydride (PMDA)/3,3′,4,4′-benzophenone tetracarboxylic acid dianhydride (BTDA)/2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6F), and bis(3-aminophenyl) methyl phospine oxide (BAP) in glacial acetic acid/acetone. Structural characterization of the resins was done by elemental analysis, IR, and ¹H-NMR. Multistep decomposition was observed in the TG scan of uncured resins in a nitrogen atmosphere. Residual weight at 800°C depended on the structure and ranged between 25 and 51%. Isothermal curing of the resins was done at 300°C for 1 h in an air atmosphere. These cured resins were stable to 350 ± 30°C and decomposed in a single step above this temperature. The char yield of the resins increased on curing and was in the range 34–70%. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:861–869, 1997     

Impregnation of Hardboard with Poly(methyl methacrylate)

The increasing deficiency of natural woods has led to the use of agricultural residues in the preparation of pulp and boards. The important agricultural residues are bagasse, straws, and cotton stalks, which accumulate in vast amounts. Some studies concerning the use of bagasse (Lumen et al., 1963), rice straw (Mobarak et al., 1975; Fadl et al., 1984), cotton stalks (Mobarak and Nada, 1975), and other agricultural residues (Lathrop and Naffziger, 1949; Aronosky and Lathrop, 1949) for producing hardboards are available. Actually, resins are added to pulp before board formation to give a final board of high strength and water resistance. The common resins are phenol-formaldehyde, urea-formaldehyde, and melamine- formaldehyde. Also, in one of our previous works, whole black liquor (Nada et al., 1982), produced from rice straw pulping process or its separated components (lignin, hemicellulose, and silica) (El-Saied et al., 1982) in the presence or absence of phenol-formaldehyde resin during hardboard preparation, was used to improve the strength properties of board. Other treatments are used to modify the hardboard or paper sheet properties, by impregnation of the sheets in resin solution (Plomely and Cottstein, 1968; Nada et al., 1981) or by polymer solution (Calleton et al., 1970; Youssef et al., in press). In addition, chemical modifica-tions such as acetylation, grafting (Smraishi et al., 1982). and cyanoethylation are carried out on wood and hardboard to improve their dimensional stability.