Papers by Sergey Shishatskiy
Membranes
Porous, porous/gutter layer and porous/gutter layer/selective layer types of membranes were inves... more Porous, porous/gutter layer and porous/gutter layer/selective layer types of membranes were investigated for their gas transport properties in order to derive an improved description of the transport performance of thin film composite membranes (TFCM). A model describing the individual contributions of the different layers’ mass transfer resistances was developed. The proposed method allows for the prediction of permeation behaviour with standard deviations (SD) up to 10%. The porous support structures were described using the Dusty Gas Model (based on the Maxwell–Stefan multicomponent mass transfer approach) whilst the permeation in the dense gutter and separation layers was described by applicable models such as the Free-Volume model, using parameters derived from single gas time lag measurements. The model also accounts for the thermal expansion of the dense layers at pressure differences below 100 kPa. Using the model, the thickness of a silicone-based gutter layer was calculate...
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Journal of Polymer Science Part A: Polymer Chemistry
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Membranes, Jan 7, 2018
Novel selective ceramic-supported thin polyimide films produced in a single dip coating step are ... more Novel selective ceramic-supported thin polyimide films produced in a single dip coating step are proposed for membrane applications at elevated temperatures. Layers of the polyimides P84, Matrimid 5218, and 6FDA-6FpDA were successfully deposited onto porous alumina supports. In order to tackle the poor compatibility between ceramic support and polymer, and to get defect-free thin films, the effect of the viscosity of the polymer solution was studied, giving the entanglement concentration (C*) for each polymer. The C* values were 3.09 wt. % for the 6FDA-6FpDA, 3.52 wt. % for Matrimid, and 4.30 wt. % for P84. A minimum polymer solution concentration necessary for defect-free film formation was found for each polymer, with the inverse order to the intrinsic viscosities (P84 ≥ Matrimid > 6FDA-6FpDA). The effect of the temperature on the permeance of prepared membranes was studied for H₂, CH₄, N₂, O₂, and CO₂. As expected, activation energy of permeance for hydrogen was higher than fo...
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Polymers
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Nanoscale research letters, 2014
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Journal of Membrane Science, 2013
ABSTRACT In this study, mixed matrix membranes (MMM) consisting of multi-walled carbon nanotubes ... more ABSTRACT In this study, mixed matrix membranes (MMM) consisting of multi-walled carbon nanotubes (MWCNTs) embedded in PIM-1 matrix have been fabricated via solution casting method and their gas transport properties are investigated. The MWCNTs were chemically functionalized with polyethylene glycol (PEG) for a better dispersion in the polymer matrix. The effect of functionalized MWCNTs (f-MWCNTs) loading on gas permeation properties of the MMM were investigated by varying the MWCNTs loading in a PIM-1 matrix from 0.5 – 3.0 wt %. The derived MMM were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and single gas permeation tests. Gas permeation measurements showed that MMM incorporated with modified and non-modified CNTs exhibited different gas separation performance. The f-MWCNT MMM show better performance compared to MMM with non-modified CNTs in terms of dispersion and permeability at 2 wt% f-MWCNTs loading without sacrificing selectivity. According to diffusivity and solubility data derived from the time-lag method, the PEG chains on MWCNTs show interaction with CO2 as indicated by an increase of the solubility of the polar gas and a reduction of the solubility of non-polar gas, which is advantageous for CO2/N2 separation. The mechanical properties and experimental sorption isotherms of CO2 and N2 of the f-MWCNTs/PIM MMM were enhanced as well.
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Nanoscale Research Letters, 2012
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Journal of Membrane Science, 2015
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European Polymer Journal, 2013
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Procedia Engineering, 2012
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Chemistry of Materials, 2014
ABSTRACT Conjugated microporous polymers (CMPs) have attracted much interest due to their intrins... more ABSTRACT Conjugated microporous polymers (CMPs) have attracted much interest due to their intrinsic porosity, outstanding stability, and high variability. However, the processing of these materials for membrane application has been limited due to their insoluble nature when synthesized as bulk material. Here we report the synthesis of freestanding CMP-nanomembranes via layer-by-layer growth of a “click” based conjugated microporous polymer on a sacrificial substrate. After dissolution of the substrate the CMP-nanomembrane can be transferred to porous substrates and continuously cover holes of up to 50 μm diameter. The CMP-nanomembranes appear defect-free as inferred from high selectivity values obtained from gas permeation experiments and from electrochemical investigation in the presence of ferrocene. The presented synthesis method represents a versatile strategy to incorporate CMP materials in functional devices for membrane separation, catalysis, or organic electronics.
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Journal of Membrane Science, 2015
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Nanoscale research letters, 2014
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RSC Adv., 2015
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Journal of Membrane Science, 2015
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ABSTRACT Permeability coefficients, X-ray diffractograms, and lifetime positron annihilation spec... more ABSTRACT Permeability coefficients, X-ray diffractograms, and lifetime positron annihilation spectra were measured for poly(4-methylpentene-1) samples with a content of isotactic fraction in the 58-98% range. It was shown that the variation of the degree of isotacticity of polymers does not change the permeability coefficients for different gases. No changes were observed in the degree of crystallinity, in the features of X-ray diffractograms, or in the parameters of lifetime spectra; these results indicate that the free volume of poly(4-methylpentene-1) is not sensitive to its stereoregularity
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ABSTRACT Permeability coefficients, diffusion coefficients, and gas solution isotherms of a glass... more ABSTRACT Permeability coefficients, diffusion coefficients, and gas solution isotherms of a glassy mesophase poly(organophosphazene)-poly[bis(tert-butyl-p-phenoxyphosphazene)] (PBPPZ) are first reported. WAXD reveal two intensive and relatively narrow maxima superimposed over an amorphous halo. The temperature dependence of the coordinate of the first maximum as well as the DSC curves indicate that the Tg of the polymer is about 50°C. A comparison of the permeability coefficients and separation factors of PBPPZ and other poly(organophosphazenes) shows that PBPPZ is among the most permselective and relatively low-permeable poly(organophosphazenes)
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Papers by Sergey Shishatskiy