Z. Pientka

Transport of Small Molecules through Polyphenylene Oxide Membranes Modified by Fullerene

Abstract Homogeneous membranes based on fullerene‐polyphenylene oxide compositions containing up to 2 wt% fullerene C60 were prepared. The effect of fullerene addition on PPO transport properties was studied in gas separation and pervaporation processes. Permeability coefficients of H2, O2, N2, CH4, and CO2 were measured; a correlation between gas transport properties and membrane free volume was established. Pervaporation properties were studied for the system with ethyl acetate synthesis reaction: quaternary system ethanol—acetic acid—water—ethyl acetate and some constituent binary and ternary mixtures. Pervaporation in binary systems, ethanol–water and ethyl acetate–water was considered with the use of the data on sorption capacities and interaction parameters. In pervaporation of a quaternary reacting mixture, the permeate containing essentially ethyl acetate was obtained. Results show that membranes with fullerene additives exhibit improved transport properties.

Polyamide Membranes Modified by Carbon Nanotubes: Application for Pervaporation

New polymer nanocomposites consist of poly(phenylene isophtalamide) (PA) modified by carbon nanotubes (CNT) were obtained by the solid state interaction method to prepare dense membranes. The investigation of the PA/CNT nanocomposites was made by Raman spectroscopy. The morphology of the dense membrane was analyzed by SEM. The transport properties of the dense polyamide membranes modified by 2 and 5 wt% CNT were studied in pervaporation of methanol/ methyl tert-butyl ether mixture. It was shown that the selectivity with respect to methanol and permeability were the highest for membranes containing 2 wt% CNT as compared to membranes of pure PA and containing 5 wt% CNT. To analyze transport properties the sorption tests and contact angle measurements were employed.

Effect of polymerization conditions of pyrrole on formation, structure and properties of high gas separation thin polypyrrole films

Abstract Gas separation membranes composed of sulfonated poly(phenylene oxide) as a support and polypyrrole were prepared by two alternative ways: (1) the support films were saturated by oxidant and then treated with pyrrole vapor; (2) the support films were saturated with pyrrole vapor and then treated with the oxidant. Study of the polymerization conditions has shown that the second method of membrane preparation results in formation of a dense polypyrrole layer on the support surface. The membranes were characterized by Fourier transform infrared spectroscopy, ultraviolet spectroscopy, optical microscopy and atomic force microscopy. Measurements of gas transport properties demonstrated that the O 2 vs. N 2 selectivity coefficient of this polypyrrole layer was 15, which is one of the highest values described in the literature.

Crosslinked ultra-thin polyimide film as a gas separation layer for composite membranes

Abstract Composite membranes with an ultra-thin polyimide separation layer were prepared by two-dimensional UV crosslinking of Langmuir-Blodgett films of a salt of polyamic acid based on 4,4′-hexafluoroisopropylidenebis(phthalic anhydride) and 2-(methacryloyloxy)ethyl 3,5-diaminobenzoate on the argon/water interface and then its deposition onto the surface of a porous support and by subsequent thermal imidization. Separation factors for CO2/N2, α = 6.4, and for O2/N2, α = 2.4, at permeation rates of the order 10−6 cm3 (STP)/(cm2 s cm Hg) were reached.

Ultrathin sectioning of polymeric materials for low-voltage transmission electron microscopy

The relief in ultrathin sections is interpreted as one of the reasons for the image contrast observed in low-voltage transmission electron microscopy. In order to clarify this, processes taking place in the course of ultrathin sectioning were monitored using a polymeric material composed of hard matrix and soft particles (high-impact polystyrene). Volume changes leading to a surface relief were observed both on cut surfaces and in ultrathin sections.

Mixed Matrix Membranes Based on Polyamide/Montmorillonite for Pervaporation of Methanol–Toluene Mixture

Novel mixed matrix membranes were obtained by the dispersion of montmorillonite (MMT) nanoparticles in poly(phenylene-iso-phtalamide) (PA) matrix. Membrane structure was determined on the basis of density measurement and morphology study by SEM. The effect of MMT inclusion on membrane hydrophilic properties was estimated by the measurement of contact angles of water, methanol, and toluene, respectively, and the calculation of surface tension. Transport properties of PA/MMT membranes were studied by use of swelling and pervaporation tests. The prepared membranes were used in the pervaporation of methanol–toluene mixtures. Total fluxes and separation factors, such as permeabilities and selectivities, were determined. It was established that the improvement of some physicochemical properties and transport parameters occurs only by inclusion up to 3 wt% MMT in the PA matrix.

Ultrathin Sectioning Of Polymeric Materials For Low-voltage Transmission Electron Microscopy: Relief On Ultrathin Sections

Ultrathin sectioning, one of the types of specimen preparations for transmission electron microscopy (TEM), has been considered the most perfect sectioning technique leading to the thinnest sections (50–100 nm). Following a study based on a newly developed low-voltage TEM technique, a relief on the ultrathin sections of polymer blends was observed that was ascribed to substantial differences in mechanical properties of the blend constituents.[1] In this study, an analogous relief was observed with a blend, the constituents of which are both hard in cutting. The origin of the surface relief on ultrathin sections of polymer blends was sought using low-voltage scanning TEM and atomic force microscopy. Polycarbonate/styrene-co-acrylonitrile blend was examined as a representative of blends with all components well under T g at room temperature. A distinct surface relief was observed on both ultrathin sections and remaining cut surfaces of the blend for low-temperature and room-temperature cutting. A rougher surface relief was found on the ultrathin sections than on the remaining cut surfaces. The surface relief was assumed to occur in the course of the cutting when extensive shearing occurs. Correspondence of the surface relief with the phase structure proves the influence of different mechanical behavior of individual blend components on the resulting morphology. #Presented in part at the 5th Multinational Congress on Electron Microscopy, Lecce, Italy, 20–25 September 2001.

Hybrid Gas Separation Membranes Containing Star-Shaped Polystyrene with the Fullerene (C 60 ) Core

A physicochemical study of novel hybrid polymer membranes based on polyphenylene oxide with a star-shaped modifier incorporated into the matrix has been conducted, and the transport properties of the membranes in the gas separation process have been studied. Poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) has been selected as the polymer matrix because of the low cost and high mechanical strength of this material. Star-shaped macromolecules (up to 5 wt %) containing six polystyrene arms grafted onto a fullerene(C60) central core have been used as the filler. The structure and physical properties of the resulting membranes have been characterized by scanning electron microscopy, membrane density measurements, differential scanning calorimetry, and thermogravimetric analysis. Film surface has been studied by contact angle measurements. The gas separation properties of the membranes have been studied by the barometric method for the following individual gases: H2, O2, N2, and CH4. Data on the separation properties have been plotted as a Robeson diagram to compare with published data. It has been shown that the incorporation of star-shaped polystyrene into the PPO matrix leads to an improvement of the separation efficiency for selected gas pairs and an increase in selectivity compared with that of the unmodified membrane.