Browsing by Author "Shapter, JG"

Now showing 1 - 7 of 7
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    Atomic layer deposition of SIO2 on porous alumina membranes: controlling the pore size and transport properties
    (SPIE, 2008-12-30) Velleman, L; Triani, G; Evans, PJ; Atanacio, AJ; Shapter, JG; Losic, D
    Atomic layer deposition (ALD) of SiO2 onto nanoporous alumina (PA) membranes was investigated with the aim of adjusting the pore size and transport properties. PA membranes from commercial sources with a range of pore diameters (20 nm, 100 nm and 200 nm) were used and modified by atomic layer deposition using tris(tert-butoxy)silanol and water as the precursor couple. By adjusting the number of deposition cycles, the thickness of the conformal silica coating was controlled, reducing the effective pore diameter, and subsequently changing the transport properties of the PA membrane. Silica coated PA membranes with desired pore diameters from <5 nm to 100 nm were fabricated. In addition to the pore size, the transport properties and selectivity of fabricated silica coated PA membranes were controlled by chemical functionalisation using a silane with hydrophobic properties. Structural and chemical properties of modified membranes were studied by dynamic secondary ion mass spectrometry (DSIMS) and scanning electron microscopy (SEM). Spectrophotometric methods were used to evaluate the transport properties and selectivity of silica coated membranes by permeation studies of hydrophobic and hydrophilic organic molecules. The resultant silica/PA membranes with specific surface chemistry and controlled pore size are applicable for molecular separation, cell culture, bioreactors, biosensing and drug delivery. © 2008 Society of Photo-Optical Instrumentation Engineers (SPIE)
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    Characterisation of methane plasma treated carbon surfaces
    (Institute of Electrical and Electronics Engineers, 2008-02-25) Deslandes, A; Jasieniak, M; Ionescu, M; Shapter, JG; Quinton, JS
    Time of Flight Secondary ion Mass Spectrometry (ToF-SIMS) was used to investigate the chemical nature of methane plasma treated graphite surfaces. Principle Component Analysis (PCA) was applied to the SIMS data, revealing chemical changes to the surfaces, in particular the extent of hydrogenation. The hydrogen content of the HOPG surface is observed to increase with systematic increases in power of the plasma treatment. These results are supported by Elastic Recoil Detection Analysis (ERDA) measurements that show a similar increase in hydrogen content. Scanning Tunneling Microscopy (STM) measurements provide insight into the morphological changes to the surface caused by the treatment, via investigating plasma-created features that are observed to increase in coverage with the increases in plasma power. © 2008 IEEE.
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    Fabrication of titania nanotube membranes by atomic layer deposition using nanoporous alumina as a template
    (Engineers Australia, 2011-09-18) Evans, PJ; Triani, G; Nambiar, M; Shapter, JG; Losic, D
    Conformal TiO2 films have been deposited onto highly oriented porous alumina arrays to characterise membranes with controlled pore modification. A suite of tools have been used to probe the evolution of these coated porous structures. Depth profiling by secondary ion mass spectroscopy revealed the distribution of elements Ti and O deposited throughout the coated porous alumina. High resolution imaging using scanning electron microscopy confirmed the reduction in pore-size as a function of deposition cycles. Following the removal of the porous alumina template, free-standing titania nanotubes were prepared which show the pore geometry of the alumina template was preserved. ©2011 Engineers Australia
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    Hydrogenation of sp(2)-bonded carbon surfaces using methane plasma
    (Elsevier, 2010-01-01) Deslandes, A; Jasieniak, M; Ionescu, M; Shapter, JG; Quinton, JS
    Highly ordered pyrolytic graphite was exposed to radio-frequency methane plasma to produce a hydrogen-terminated carbon surface. The effects of treatment parameters, namely exposure time, applied power and methane pressure, upon the treated surfaces’ chemical and morphological properties were systematically investigated. Scanning tunnelling microscopy measurements showed growth features on the plasma treated surface, the coverage of which was shown to increase with plasma exposure time or applied plasma power and decrease with gas pressure. Analyses of post-treated surface structures (via static secondary ion mass spectrometry with the aid of principle component analysis) showed an increase in surface hydrogen with plasma exposure time, applied plasma power and decreasing gas pressure. The results of these analyses were further supported by elastic recoil detection analysis measurements, which showed similar trends for the experimental parameters on the resultant surface hydrogen content. © 2010, Elsevier Ltd.
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    Structural and chemical modification of porous alumina membranes
    (Elsevier, 2009-11) Velleman, L; Triani, G; Evans, PJ; Shapter, JG; Losic, D
    Structural and chemical modification of porous anodic alumina (AAO) membranes was investigated with the aim of fine-tuning pore diameters and chemical selectivity. AAO membranes from commercial sources with pore diameters (20, 100 and 200 nm) were used as the substrate. Atomic layer deposition (ALD) of silica (SiO2) has been used for membrane structural modification using tris(tert-butoxy)silanol and trimethylaluminium as the precursor couple. By adjusting the number of ALD deposition cycles (3–20), the effective pore diameter of AAO membranes was significantly reduced to desired values (<10 nm) improving the separation properties of commercial membranes. The chemical functionalization of silica coated AAO membranes with a perfluorodecyldimethylchlorosilane (PFDS) shows that the transport and selectivity properties of silica composite AAO membranes can be varied by functionalization using silane chemistry. The hydrophobic PFDS-modified membranes showed enhanced sensitivity (flux ratio 5.52) to the transport of hydrophobic molecules (tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate (Rubpy), over hydrophilic molecules (rose bengal (RB)). Structural and chemical properties of modified membranes were confirmed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDAX), dynamic secondary ion mass spectrometry (DSIMS), and contact angle measurements. The resultant silica coated commercial AAO membranes with specific surface chemistry and controlled pore size are applicable for advanced molecular separation, cell culture, tissue engineering, biosensing and drug delivery. © 2009, Elsevier Ltd.
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    Study of titania modified porous alumina membranes for protein transport and separation
    (Engineers Australia, 2011-09-18) Nambiar, M; Evans, PJ; Triani, G; Shapter, JG; Losic, D
    The use of nanoporous membranes in molecular separation or sieving, which involve the separation of molecular mixtures, is gaining rapid interest. The ability to modify and alter their pore size and dimensions, along with the physical and chemical properties of the material that constitute these pores make them highly sensitive to such applications, particularly protein separation. Our study investigated the use of titania modified porous anodic alumina (AAO) membranes. Titania was deposited using atomic layer deposition (ALD) for different number of cycles in order to generate membranes with reduced poresizes ranging from 100nm-10nm. Protein permeation experiments using bovine serum albumin (BSA) and Lysozyme (Lys) were conducted to show selectivity in transport and separation of the proteins. Transport occurred by diffusion and a subsequent decrease in flow rate was observed with decrease in pore size of the membranes. In addition, the use of titania modified AAO membranes demonstrated minimal extent of non-specific absorption of proteins along the pores during permeation when subject to UV radiation. The resultant titania coated AAO membranes achieved controlled reduction of pore size using ALD and are thus, applicable for advanced protein transport, separation and catalysis. © 2011 Engineers Australia
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    ToF-SIMS characterisation of methane- and hydrogen-plasma-modified graphite using principal component analysis.
    (Wiley-Blackwell, 2009-03) Deslandes, A; Jasieniak, M; Ionescu, M; Shapter, JG; Fairman, C; Gooding, JJ; Hibbert, DB; Quinton, JS
    Time of flight secondary ion mass spectrometry (ToF-SIMS) has been used to determine the extent of surface modification of highly ordered pyrolytic graphite (HOPG) samples that were exposed to radio-frequency methane and hydrogen plasmas. The ToF-SIMS measurements were examined with the multivariate method of principal component analysis (PCA), to maximise the amount of spectral information retained in the analysis. This revealed that the plasma (methane or hydrogen plasma) modified HOPG exhibited greater hydrogen content than the pristine HOPG. The hydrogen content trends observed from the ToF-SIMS studies were also observed in elastic recoil detection analysis measurements. The application of the ToF-SIMS PCA method also showed that small hydrocarbon fragments were sputtered from the hydrogen-plasma-treated sample, characteristic of the formation of a plasma-damaged surface, whereas the methane-plasma-treated surface sputtered larger hydrocarbon fragments, which implies the growth of a polymer-like coating. Scanning tunnelling microscopy measurements of the modified surfaces showed surface features that are attributable to either etching or film growth after exposure to the hydrogen or methane plasma. © 2009, Wiley-Blackwell.