Hydroxyl functionalized multi-walled carbon nanotubes (MWCNTs) were blended with Polyacrylonitrile (PAN) to prepare ultrafiltration membranes by a phase inversion process. Three different concentrations of MWCNTs were used in PAN, i.e. 0.5, 1 and 2 wt%. The water flux of the membranes increased by 63% at 0.5 wt% loading of MWCNTs compared to neat PAN membranes. The water flux decreased upon further increase in the concentration of MWCNTs, but at 2 wt% loading it was still higher compared to pure PAN membranes. The surface hydrophilicity of the membranes was enhanced upon the addition of MWCNTs, as observed by contact angle measurements. The increased hydrophilicity might have an impact on the improved water flux. All the membranes showed a molecular weight cut off (MWCO) of approximately 50 Kg/mol. Surface pore size analysis by scanning electron microscopy (SEM) showed no significant difference in the mean pore size of the nanocomposite membranes compared to the neat membranes. The cross section morphology was influenced by the introduction of MWCNTs where less but enlarged macrovoids were observed, particularly prominent at a loading of 2 wt% MWCNTs. The membranes containing 2wt% MWCNTs showed 36% improvement in resistance against compaction compared to neat membranes. Furthermore, the tensile strength of the membranes at 2wt% MWCNTs loading increased over 97% compared to neat ones.

Graphene, graphene-based nanomaterials (GBNs), and carbon nanotubes (CNTs) are being investigated as potential substrates for the growth of neural cells. However, in most in vitro studies, the cells were seeded on these materials coated with various proteins implying that the observed effects on the cells could not solely be attributed to the GBN and CNT properties. Here, we studied the biocompatibility of uncoated thermally reduced graphene (TRG) and poly(vinylidene fluoride) (PVDF) membranes loaded with multi-walled CNTs (MWCNTs) using neural stem cells isolated from the adult mouse olfactory bulb (termed aOBSCs). When aOBSCs were induced to differentiate on coverslips treated with TRG or control materials (polyethyleneimine-PEI and polyornithine plus fibronectin-PLO/F) in a serum-free medium, neurons, astrocytes, and oligodendrocytes were generated in all conditions, indicating that TRG permits the multi-lineage differentiation of aOBSCs. However, the total number of cells was reduced on both PEI and TRG. In a serum-containing medium, aOBSC-derived neurons and oligodendrocytes grown on TRG were more numerous than in controls; the neurons developed synaptic boutons and oligodendrocytes were more branched. In contrast, neurons growing on PVDF membranes had reduced neurite branching, and on MWCNTs-loaded membranes oligodendrocytes were lower in numbers than in controls. Overall, these findings indicate that uncoated TRG may be biocompatible with the generation, differentiation, and maturation of aOBSC-derived neurons and glial cells, implying a potential use for TRG to study functional neuronal networks.

No abstract

Baytubes were kindly supplied by Bayer MaterialScience. Styroclear GH62 (AS-SB 26 ) was cordially provided by BASF. J.A. acknowledges a DAAD-HGF fellowship. The authors acknowledge financial support by the 7th Framework Programme of the European Commission (HARCANA (NMP3-LA-2008-213277)) and HASYLAB.Films based on a commercial block copolymer and multiwall carbon nanotubes (MWCNTs) were prepared by solution casting. The block copolymer has a star asymmetric chain architecture, with polystyrene chains of different lengths and a polybutadiene core. The block copolymer has a lamellar morphology. The MWCNT were grafted with polystyrene chains under atom transfer radical polymerization (ATRP) conditions. The nanocomposites were characterized by transmission electron microscopy (TEM) and simultaneous small angle X-ray scattering (SAXS)/strain-stress tests. The morphology of the nanocomposites is influenced by the polystyrene chain grafted from the MWCNT. In the case of the nanocomposite based on pristine MWCNT, most of the nanotubes intersect the lamellar domains of the block copolymer. With the increase of the molecular weight and the grafting chain density of the polystyrene anchored to the MWCNT, a favorable interaction between the polystyrene microdomain phases in the block copolymer and the MWCNT is observed. In the case where the MWCNT grafted with the relative highest molecular weight (20 kgÁmol À1 ) and polystyrene grafted content (> 90 wt%), the MWCNT locally templates the lamellar morphology of the block copolymer. The effect on the block copolymer is analyzed based on the orientation of the morphology under an external deformation.

The preparation and morphological characterization of a so-called composite membrane based on a 3-miktoarm star terpolymer on a support layer is reported. It is demonstrated that different levels of order and different morphological orientations can be obtained by directly casting the star terpolymer solution on the support, depending on the prior treatment of the support layer and the casting conditions.

The bulk morphology of poly(1,4-butadiene)-block-polystyrene-block-poly (ethylene oxide) (PB-b-PS-b-PEO) and polyethylene-block-polystyrene-block-poly (ethylene oxide) (PE-b-PS-b-PEO) triblock terpolymers is analyzed under a thermal protocol. This allows the investigation of the morphology during the occurrence of thermal transitions, such as crystallization and melting, which is a neat way of studying the competition between microphase separation and crystallization for the morphology formation. Only one of the studied systems presented a morphological transition upon melting of the PEO and the PE blocks, attributed to the crystallization of the PE block in finite interconnected domains. All the other systems presented no morphological transitions during the thermal scan. The results prove that the crystallization only disrupt the microphases generated in the molten state under very specific circumstances for these block copolymers. V V C 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3197-3206, 2007

The solution-diffusion with imperfections model has been used together with diffusion models such as the Vrentas & Duda diffusion theory and the Wesselingh & Bollen multicomponent diffusion model as a tool to successfully describe the permeation behavior of mixtures of ketones and glycols through polydimethylsiloxane composite membranes in a cross-flow membrane cell for pressures varying from 10 to 40 bar. The model has shown the great importance of an accurate determination of the diffusion coefficients and the average concentration of permeants inside the membrane into the successful modeling of nanofiltration experiments.

No abstract