Polymer Nanocomposite Membranes Research Articles

Carbon nanotube composite membranes of brominated poly(2,6-diphenyl-1,4-phenylene oxide) for gas separation

The mechanical strength of polymeric membranes is one of the limitations in their applications. Carbon nanotubes (CNTs) are very effective in reinforcing polymeric materials, but it is unknown whether they degrade the membranes’ gas separation performance. Using brominated poly(2,6-diphenyl-1,4-phenylene oxide) (BPPO dp) as an example, we show that pristine single-wall CNTs (SWNTs) and multi-wall CNTs (MWNTs) formed polymeric nanocomposite membranes with BPPO dp. The composite membranes had an increased CO 2 permeability but a similar CO 2/N 2 selectivity compared to the corresponding pure-polymer membrane. The CO 2 permeability increased with increasing the CNT content and reached a maximum of 155 Barrer at 9 wt% of SWNTs, or 148 Barrer at 5 wt% of MWNTs. The CO 2/N 2 separation performance was insensitive to the MWNT diameter or length. Carboxylic acid-functionalized SWNTs (COOH-SWNTs) dispersed more uniformly in BPPO dp, and neither increased the gas permeability nor deteriorated the gas separation performance. Thus, it is feasible to add CNTs to polymeric membranes for improved mechanical strength without deteriorating the gas separation performance of the membranes. The pristine CNT-enhanced gas permeability was attributed to the formed nanogaps surrounding the CNTs.

Heated-Tip AFM: Applications in Nanocomposite Polymer Membranes and Energetic Materials

Abstract Atomic Force Microscopy (AFM) is a key technique for the measurement and analysis of samples when nanoscale topography is of interest. It offers a number of complementary probing modes that extend an AFM's measurement capability to a wide range of material and transport properties of surfaces, including hardness, friction, conductivity and adhesion among others. Sample temperature controlled AFM extends the study of surface morphology and properties to include changes in the material phases. Recently, silicon microfabricated AFM cantilevers that have integrated heaters, as shown in figure 1, have become commercially available. These cantilevers were initially developed for probe based data storage by researchers at IBM Zurich, Figure 1. With the availability of these cantilevers, AFM measurements can be performed where the tip is heated as opposed to the sample.

Membranes with Oriented Polyelectrolyte Nanodomains

Polymer−polymer nanocomposite membranes with polyelectrolyte nanodomains oriented normal to the plane of the membrane were prepared using track-etched membranes as a host matrix. The oriented nanodomains of polyelectrolyte were synthesized in tubular and fibril forms by a plasma-induced surface graft polymerization, where nanodomains with aspect ratios as high as 240 were obtained. The morphology of nanodomains was confirmed by scanning electron microscopy, attenuated total reflection Fourier transform infrared spectroscopy, and energy dispersive spectroscopy. The specific conductivity of the polyelectrolyte nanodomains increased with decreasing domain size with the highest value 6 times higher than that of the isotropic bulk polyelectrolyte gel membrane. Mechanical strength of the nanocomposite was similar to the matrix in both the dry and the hydrated state, unlike the bulk polyelectrolyte gel membrane. The membranes synthesized in this study with oriented polyelectrolyte nanodomains demonstrate the abi...

Characterization of Nanocomposite Polymeric Membrane

Composite membrane has good permeability and selectivity for gases, which depends upon the operating conditions. The solubility and diffusivity of the penetrant in the polymer matrix control the transport through non-porous dense membrane. In the present work, the nano sized particles of Co0.6Zn0.4Fe2O4 were prepared by the co-precipitation method and characterized by the XRD technique with particle size of 10 nm. Nanocomposite polycarbonate membranes were studied before and after irradiation by the 35Cl9+ ion of 120 MeV at the Nuclear Science Centre, New Delhi. The distribution of nanoparticles throughout the membrane was characterized by the optical microscope. Gas transport properties of H2, CO2 and air for these nanocomposite membranes were investigated. It was found that membrane containing nanoparticles shows low permeability with high permselectivity. After irradiation by swift heavy ions (SHI), high gas permeability and high permselectivity has been observed for these nanocomposite membranes.

Preparation of TiO 2 self-assembled polymeric nanocomposite membranes and examination of their fouling mitigation effects in a membrane bioreactor system

In this study, we investigated the ability of TiO 2 self-assembled nanocomposite membranes to mitigate fouling effects during the filtration of membrane bioreactor (MBR) mixed liquor. Our results showed that membrane fouling was significantly reduced by the immobilization of TiO 2 nanoparticles on the surface of these membranes. The fouling mitigation effect increased with increasing amounts of TiO 2 nanoparticles and the initial sharp flux decline observed for neat polymeric membranes was alleviated by TiO 2 immobilization. Adsorbed foulants on the surface of nanocomposite membranes were more readily dislodged by shear force than those on neat polymeric membranes due to the increased hydrophilicity of the membrane. Accordingly, the amount and the rate of membrane fouling decreased in the nanocomposite membranes.

Pervaporation separation of water + isopropanol mixtures using novel nanocomposite membranes of poly(vinyl alcohol) and polyaniline

Novel nanocomposite polymeric membranes containing nanosized (30–100 nm) polyaniline (PANI) particles dispersed in poly(vinyl alcohol) (PVA) were prepared and used in the pervaporation separation of water–isopropanol feed mixtures ranging from 10 to 50 mass% of water at 30 °C. Of the three nanocomposite membranes prepared, the membrane containing 40:60 surface atomic concentration ratio of PANI:PVA produced the highest selectivity of 564 compared to a value of 77 observed for the plain PVA membrane. Flux of the nanocomposite membranes was lower than those observed for the plain PVA membrane, but selectivity improved considerably. Membranes were characterized by differential scanning calorimetry, dynamic mechanical thermal analyzer, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The highest selectivity with the lowest flux was observed for 10 mass% water containing feed mixture. Flux increased with increasing amount of water in the feed, but selectivity decreased considerably. These results were attributed to the acid-doped PANI particles in the PVA membrane as a result of change in the micromorphology of the nanocomposite membranes. In addition, molar mass between cross-links and fractional free volume of the membranes are responsible for the varying membrane performance. Temperature effect on permeability was investigated for 10 mass% water containing feed with the membrane containing higher concentration of PANI particles, the presence of which could be responsible for varied effect of water permeation through the membrane. Membranes of this study could remove as much as 98% of water from the feed.

Polymer nanocomposite membranes for DMFC application

Polymer nanocomposite membranes based on sulphonated poly(ether ether ketone) (SPEEK) containing different weight percentages of synthetic non-spherical nanofillers such as laponite and MCM-41 were prepared and characterised for direct methanol fuel cells (DMFC). Prior to the preparation of the composite membranes, they were modified using organo silanes. The results showed that there was a decrease in methanol and water permeability with the increasing content of modified laponite and MCM-41. While the membranes containing higher (>10) weight percentages of silicates displayed lower proton conductivity values than plain polymer, the lower percentages even showed better values than the plain. The results are compared with the membranes containing spherical nanofillers, namely Aerosil and an isotropic silica network system in order to see the effect of shape of nanofillers on the properties of the composite membranes. Among all shapes, membranes containing silica network had the lowest permeability but they also had poor conductivity values. Much more evident than the effect of form or aspect was the influence of the filler surface modification. In all the cases, organic modification drastically decreased methanol and water permeabilities. A good agreement between the experiment and theory was found for the permeability reduction for membranes containing lower weight percentages of layered silicates assuming aspect ratio of 125 for laponite.

Highly CO2‐Permeable and Selective Polymer Nanocomposite Membranes

As technologies turn to more efficient routesto remove CO2from mixed gas streams for H2or air purification, new cost‐effective multifunctional materials are needed for the separation processes. Here, hybrid poly(ethylene glycol)/fumed silica nanocomposite membranes exhibiting high CO2/H2selectivity (> 11) and CO2permeability (∼ 83 Barrer), as well as robust mechanical properties and optical clarity, are reported (see Figure).

Proton Conducting Organic/Inorganic Nanocomposite Polymer Electrolytic Membrane Synthesized by Sol-Gel Process

ABSTRACTIn this paper, new synthetic routes have been investigated for the preparation of Organic/inorganic nanocomposite polymer membranes consisting of SiO2 /PTMO(polytetramethylene oxide) hybrids and novel proton conducting materials. These materials have been synthesized through sol-gel processes in flexible, ductile, free-standing thin membrane form. The hybrid membrane has been found to be thermally stable up to 160 C and possesses proton conductivities of approximately 10−4 S/cm from a room temperature to 160 C.