Synthesis of TiO2 nanotube films via pulsed laser deposition followed by a hydrothermal treatment

Titanium dioxide nanotube (TNT) films were prepared by pulsed laser deposition (PLD) of P25 and P90 TiO₂ nanoparticles onto stainless steel foils followed by a hydrothermal treatment (HT). Heating the PLD films in a TNT precursor solution at 150°C resulted in a well-adhered dense mat of TNTs that were ～10?nm in diameter with a pore size of ～4?nm. The TiO₂ nanotube films were characterised by SEM, TEM, XRD and Raman spectroscopy.     

Layer-by-layer assembly of titanate nanosheets/poly- (ethylenimine) on PEN films

Alternating layers of TiO₂ nanosheets and poly(ethylenimine) were sequentially dip coated onto a polyethylene naphthalate substrate (PEN) using layer-by-layer assembly. UV-vis spectroscopy shows a linear growth of the PEI/nanosheets bilayer on the PEN substrate. The cross-section microstructure of the LBL film was studied using scanning electron microscopy (SEM). Helium permeability measurement showed that the titania nanosheet/PEI bilayers reduced the permeation rate of He through the coated PEN film.     

An analysis of mobile Internet access in Thailand: Implications for bridging the digital divide

Mobile Internet is growing around the world, bypassing the poor legacy of wired infrastructure. This growth can be observed even in developing countries like Thailand. To cope with this trend, this study attempts to provide guidance to a national regulatory agency (NRA) by addressing the following question: What are the key determinant factors for individual consumer to access mobile Internet? A discrete choice model is employed to examine empirically whether price, service, and application attributes, socio-economic variables, and service provider have a systematic link with the decision of the consumer. The data from a national survey in 2010 commissioned by the National Telecommunications Commission (NTC) of Thailand are used for the analysis.     

Stabilization of immiscible polymer blends using structure directing metal organic frameworks (MOFs)

We have developed a novel approach for compatibilizing immiscible polymer blends using metal organic frameworks (MOFs). For the first time we demonstrated that the droplet diameter of the dispersed phase in a 1:1 immiscible polymer blend composed of 6FDA-DAM:DABA [copolymer of 4,4-hexafluoroisopropylidene diphthalic anhydride (6FDA), 2,4,6-trimethyl-1,3-phenylenediamine and 3,5-diaminobenzoic acid (DABA)], and polybenzimidazole (PBI), is dramatically reduced obtaining a uniform microstructure with the incorporation of as low as 5% (w/w) of the zeolitic imidazolate framework-8 (ZIF-8). This indicates a large improvement in the compatibility of the immiscible polymers with the inclusion of ZIF-8. As the ZIF-8 loading was further increased to 10% (w/w), the droplet diameter further decreased resulting in even higher compatibility. The compatibilizing effect can be attributed to a reduction in the interfacial energy of the immiscible polymers due to the interfacial localization of ZIF-8. This MOF based compatibilization of immiscible polymer blends can open up opportunities for the combination of different properties of polymers in membrane-based separations and in more applications.     

Flammability and thermomechanical properties of dianhydride‐modified polybenzoxazine composites reinforced with carbon fiber

Composites based on carbon fiber (CF) and benzoxazine (BA‐a) modified with PMDA were investigated. The flammability of the carbon fiber composites was examined by limiting oxygen index (LOI) and UL‐94 vertical tests. The LOI values increased from 26.0 for the CF/poly(BA‐a) composite to 49.5 for the CF‐reinforced BA‐a/PMDA composites as thin as 1.0 mm and the CF‐reinforced BA‐a/PMDA composites were also achieved the maximum V‐0 fire resistant classification. Moreover, the incorporation of the PMDA into poly(BA‐a) matrix significantly enhanced the T_g and the storage modulus (E') values of the CF‐reinforced BA‐a/PMDA composites rather than those of the CF/poly(BA‐a). The T_g values and storage moduli of the obtained CF‐reinforced BA‐a/PMDA composites were found to have relatively high value up to 237°C and 46 GPa, respectively. The CF‐reinforced BA‐a/PMDA composites exhibited relatively high degradation temperature up to 498°C and substantial enhancement in char yield with a value of up to 82%, which are somewhat higher compared to those of the CF/poly(BA‐a) composite, i.e., 405°C and 75.7%, respectively. Therefore, due to the improvement in flame retardant, mechanical and thermal properties, the obtained CF‐reinforced BA‐a/PMDA composites exhibited high potential applications in advanced composite materials that required mechanical integrity and self‐extinguishing property. POLYM. COMPOS., 34:2067–2075, 2013. © 2013 Society of Plastics Engineers     

Synthesis of gold nanoclusters: a fluorescent marker for water-soluble TiO2 nanotubes

The first example of a water-soluble wrapped titania nanotube (TNT) decorated with fluorescent gold nanoparticles has been prepared. Gold nanoparticles ～ 1.6 nm in diameter were grown on the TiO(2) nanotubes using a thiolactic acid linker to control the size. The gold clusters emit at 660 nm in water and were imaged using confocal microscopy. The gold decorated TNTs were suspended in water by wrapping the nanotubes with poly-L-arginine.