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Papers by Gordon Armstrong
BACKGROUND: Carbon nanotubes (CNT) are fast becoming key components in the production of high-str... more BACKGROUND: Carbon nanotubes (CNT) are fast becoming key components in the production of high-strength composite materials. Two methods to prepare nanocomposites by covalent bonding between an epoxy matrix and functionalised CNT which acted as cross-linkers during polymerisation were investigated. RESULTS: In the standard method, 1 wt% functionalised CNT was dispersed in epoxy, hardener added and the composite was cured. In the masterbatch approach, 1 wt% functionalised CNT were mixed with epoxy in the presence of triethylamine accelerator, then cured. This yielded partially-cured epoxy; additional hardener was required to Page 2 of 27 achieve complete curing. Improvements were observed in storage modulus (E′) flexural modulus (EB), wear resistance and hardness were also improved. Thermal stability did not change appreciably for samples prepared by either the standard or masterbatch methods. Variations in the results obtained as a function of preparation method, functionalised CNT a...
Irish Journal of Paramedicine
BackgroundThe unpredictability of the nature of the next call is a basic feature of Emergency Ser... more BackgroundThe unpredictability of the nature of the next call is a basic feature of Emergency Services; the call could vary from a trauma victim, to a hypothermic patient or a prehospital birth. All patients (other than those who are pyrexic) have in common the need for a warm environment to prevent deterioration in their condition. Multiple observation studies found that patients suffering from various levels of trauma, arrived in the Emergency Department with hypothermia. Hypothermia, a core temperature…
European Journal of Inorganic Chemistry
European Journal of Physics
This topical review will provide a survey of the current state of the art in 'hyphenated' techniq... more This topical review will provide a survey of the current state of the art in 'hyphenated' techniques for characterisation of bulk materials, surface, and interfaces, whereby two or more analytical methods investigating different properties are applied simultaneously to the same sample to better characterise the sample than can be achieved by conducting separate analyses in series using different instruments. It is intended for final year undergraduates and recent graduates, who may have some background knowledge of standard analytical techniques, but are not familiar with 'hyphenated' techniques or hybrid instrumentation. The review will begin by defining 'complementary', 'hybrid' and 'hyphenated' techniques, as there is not a broad consensus among analytical scientists as to what each term means. The motivating factors driving increased development of hyphenated analytical methods will also be discussed. This introduction will conclude with a brief discussion of gas chromatography-mass spectroscopy and energy dispersive X-ray analysis (EDX) in electron microscopy as two examples, in the context that combining complementary techniques for chemical analysis were among the earliest examples of hyphenated characterisation methods. The emphasis of the main review will be on techniques which are sufficiently well-established that the instrumentation is commercially available, to examine physical properties including physical, mechanical, electrical and thermal, in addition to variations in composition, rather than methods solely to identify and quantify chemical species. Therefore, the proposed topical review will address three broad categories of techniques that the reader may expect to encounter in a well-equipped materials characterisation laboratory: microscopy based techniques, scanning probe based techniques, and thermal analysis based techniques. Examples drawn from recent literature, and a concluding case study, will be used to explain the practical issues that arise in combining different techniques. We will consider how the complementary and varied information obtained by combining these techniques may be interpreted together to better understand the sample in greater detail than that was possible before, and also how combining different techniques can simplify sample preparation and ensure reliable comparisons are made between multiple analyses on the same samples-a topic of particular importance as nanoscale technologies become more prevalent in applied and industrial research and development. The review will conclude with a brief outline of the emerging state of the art in the research laboratory, and a suggested approach to using hyphenated techniques, whether in the teaching, quality control or research and development laboratory.
Composites Science and Technology, Jun 1, 2007
This paper reports a 4.5 fold increase in the Young&#... more This paper reports a 4.5 fold increase in the Young's modulus of a semi-crystalline polymer, poly(vinyl alcohol), with the addition of carbon nanotubes. The importance of nanotube diameter is addressed with the production of four composite solutions with each solution containing ...
Magnetic Resonance in Chemistry, 2005
High-resolution 1 H and 15 Nf 1 Hg solid-state NMR experiments were conducted on two ureidopyrimi... more High-resolution 1 H and 15 Nf 1 Hg solid-state NMR experiments were conducted on two ureidopyrimidinone model compounds: dimeric 2-butylureido-6-methyl-4-pyrimidinone (1) and its bifunctional analogue N,N-1,6-hexanediyl(2-ureido-6-methyl-4-pyrimidinone) (4). High magic angle spinning rates and 1 H decoupling schemes were used to increase the proton spectral resolution. Upon heating 1 to 440 K, an increase in mobility was observed for non-hydrogen-bonded protons; the dimer remained in keto tautomeric form, which is capable of much stronger intermolecular hydrogen bonding than the enol tautomer. From these findings, it was concluded that this ureidopyrimidinone moiety should allow the design of strongly bonded molecular assemblies whose thermal stability compares favourably with that of conventional engineering polymers.
ACS Applied Materials & Interfaces, 2015
Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two... more Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two methods, the layer-by-layer (LBL) assembly technique by employing a pentaerythritol-based ruthenium(II) metallodendrimer as a cationic moiety and also by entrapping the POM in a conducting polypyrrole film. The redox behavior of the constructed films was studied by using cyclic voltammetry and electrochemical impedance spectroscopy. The surface morphologies of the constructed multilayers were examined by scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy was conducted to confirm the elements present within the fabricated films. The multilayer assembly was also investigated for its catalytic efficiency towards the reduction of nitrite.
European Journal of Physics, 2015
Encyclopedia of Polymeric Nanomaterials, 2013
Electrochimica Acta, 2015
Keywords: polyoxometalate electrocatalysis layer-by-layer transition metal ion-substituted crownt... more Keywords: polyoxometalate electrocatalysis layer-by-layer transition metal ion-substituted crowntype polyoxometalate nitrite reduction
ACS Applied Materials & Interfaces, 2015
Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two... more Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two methods, the layer-by-layer (LBL) assembly technique by employing a pentaerythritol-based ruthenium(II) metallodendrimer as a cationic moiety and also by entrapping the POM in a conducting polypyrrole film. The redox behavior of the constructed films was studied by using cyclic voltammetry and electrochemical impedance spectroscopy. The surface morphologies of the constructed multilayers were examined by scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy was conducted to confirm the elements present within the fabricated films. The multilayer assembly was also investigated for its catalytic efficiency towards the reduction of nitrite.
A tetra Ru-substituted polyoxometalate Na10[{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2] (Ru4POM) has been su... more A tetra Ru-substituted polyoxometalate Na10[{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2] (Ru4POM) has been successfully immobilised onto glassy carbon electrodes and indium tin oxide (ITO) coated glass slides through the employment of a conducting polypyrrole matrix and the layer-by-layer (LBL) technique. The resulting Ru4POM doped polypyrrole films showed stable redox behavior associated with the Ru centres within the Ru4POM, whereas, the POM's tungsten-oxo redox centres were not accessible. The films showed pH dependent redox behavior within the pH range 2-5 whilst exhibiting excellent stability towards redox cycling. The layer-by-layer assembly was constructed onto poly(diallyldimethylammonium chloride) (PDDA) modified carbon electrodes by alternate depositions of Ru4POM and a Ru(II) metallodendrimer. The resulting Ru4POM assemblies showed stable redox behavior for the redox processes associated with Ru4POM in the pH range 2-5. The charge transfer resistance of the LBL films was calculated through AC-Impedance. Surface characterization of both the polymer and LBL Ru4POM films was carried out using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Initial investigations into the ability of the Ru4POM LBL films to electrocatalytically oxidise water at pH 7 have also been conducted.
The Analyst
A conducting polymer was used for the immobilization of various transition metal ion-substituted ... more A conducting polymer was used for the immobilization of various transition metal ion-substituted Dawson-type polyoxometalates (POMs) onto glassy carbon electrodes. Voltammetric responses of films of different thicknesses were stable within the pH domain 2-7 and reveal redox processes associated with the conducting polymer, the entrapped POMs and incorporated metal ions. The resulting POM doped polypyrrole films were found to be extremely stable towards redox switching between the various redox states associated with the incorporated POM. An amperometric sensor for hydrogen peroxide detection based upon the POM doped polymer films was investigated. The detection limits were 0.3 and 0.6 μM, for the Cu(2+)- and Fe(3+)-substituted POM-doped polypyrrole films respectively, with a linear region from 0.1 up to 2 mM H(2)O(2). Surface characterization of the polymer films was carried out using atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy.
Polymer International, 2009
... Editorial. In Focus: Advances in Epoxy Chemistry. Gordon Armstrong Organisers Advances in E... more ... Editorial. In Focus: Advances in Epoxy Chemistry. Gordon Armstrong Organisers Advances in Epoxy Chemistry June 2009 1,* ,; David Birkett Organisers Advances in Epoxy Chemistry June 2009 2. Article first published online: 13 AUG 2009. DOI: 10.1002/pi.2659. ...
Journal of Colloid and Interface Science, 2011
Titania-silver (TiO 2 -Ag) and alumina-silver (Al 2 O 3 -Ag) composite nanoparticles were synthes... more Titania-silver (TiO 2 -Ag) and alumina-silver (Al 2 O 3 -Ag) composite nanoparticles were synthesised by a simple, reproducible, wet chemical method under ambient conditions. The surface of the oxides was modified with oleic acid, which acted as an intermediate between the oxide surface and the silver nanoparticles. The resulting composite nanoparticles were thoroughly characterized by XRD, TEM, XPS, FTIR and TGA to elucidate the mode of assembly of Ag nanoparticles on the oxide surfaces.
![Research paper thumbnail of Redox, surface and electrocatalytic properties of layer-by-layer films based upon Fe(III)-substituted crown polyoxometalate [P8W48O184Fe16(OH)28(H2O)4]20](https://attachments.academia-assets.com/43423036/thumbnails/1.jpg)
](Electrochimica Acta
The electrocatalytic ability of the iron-substituted crown-type polyoxometalate (POM) Li4K16[P8W4... more The electrocatalytic ability of the iron-substituted crown-type polyoxometalate (POM) Li4K16[P8W48O184Fe16(OH)28(H2O)4]·66H2O·2KCl (P8W48Fe16) towards the reduction of both nitrite and hydrogen peroxide reduction has been studied in both the solution and immobilized states for the POM. P8W48Fe16 was surface immobilised onto carbon electrode surfaces through employment of the layer-by-layer technique (LBL) using pentaerythritol-based Ru(II)-metallodendrimer [RuD](PF6)8 as the cationic layer within the resulting films. The constructed multilayer films have been extensively studied by various electrochemical techniques and surface based techniques. Cyclic voltammetry and impedance spectroscopy have been utilized to monitor the construction of the LBL film after the deposition of each monolayer. The electrochemical behaviour of both a cationic and anionic redox probes at the LBL films has been undertaken to give indications as to the film's porosity. The elemental composition and th...
Polymer Bulletin, 2012
Current interest in antimicrobial coatings is driven by an urgent need for more effective strateg... more Current interest in antimicrobial coatings is driven by an urgent need for more effective strategies to control microbial infection. In this study, antimicrobial nanoclays were prepared by ion-exchange of sodium montmorillonite (MMT) with silver ions which have been previously reported to exhibit biocidal activity. The extent of ion exchange achieved was estimated by x-ray photoelectron spectroscopy (XPS). The silver-modified nanoclay (AgMMT) fully inhibited growth of Gram negative Escherichia coli DH5α (E. coli) over 24 hours;
Porous silicon is generally achieved through electro-chemical etching or chemical etching of bulk... more Porous silicon is generally achieved through electro-chemical etching or chemical etching of bulk silicon in hydrofluoric acid based solutions. The work presented here explores the effect of a chemical etching process on a metallurgical grade silicon powder. It is found that the metallurgical grade silicon particles contain surface bound impurities that induce a porous structure formation upon reaction with the chemical etchant applied. The correlation between the resultant porous structure formed due to the material composition is examined in detail. The elemental composition is determined using a combination of X-ray Photoelectron Spectroscopy and Time of Flight Secondary Ion Mass Spectroscopy. The porous structure is analysed using Transmission Electron Microscopy and Scanning Electron Microscopy. Three samples of the silicon particles analysed for this study include an un-etched bulk silicon powder sample and two samples of chemically etched powder. Pore formation within the particles is found to be dependent on the presence, dispersion, and local concentration of surface bound impurities within the starting powder.
Polymer International, 2009
BACKGROUND: Carbon nanotubes (CNTs) are fast becoming key components in the production of high-st... more BACKGROUND: Carbon nanotubes (CNTs) are fast becoming key components in the production of high-strength composite materials. Two methods to prepare nanocomposites by covalent bonding between an epoxy matrix and functionalised CNTs that acted as cross-linkers during polymerisation were investigated. RESULTS: In the standard method, 1 wt% functionalised CNTs was dispersed in epoxy, hardener was added and the composite was cured. In the masterbatch approach, 1 wt% functionalised CNTs was mixed with epoxy in the presence of triethylamine accelerator, then cured. This yielded partially cured epoxy; additional hardener was required to achieve complete curing. Improvements were observed in storage modulus (E ), flexural modulus (E B ), wear resistance and hardness. Thermal stability did not change appreciably for samples prepared by either the standard or masterbatch methods. Variations in the results obtained as a function of preparation method, functionalised CNTs and hardener used are discussed.
BACKGROUND: Carbon nanotubes (CNT) are fast becoming key components in the production of high-str... more BACKGROUND: Carbon nanotubes (CNT) are fast becoming key components in the production of high-strength composite materials. Two methods to prepare nanocomposites by covalent bonding between an epoxy matrix and functionalised CNT which acted as cross-linkers during polymerisation were investigated. RESULTS: In the standard method, 1 wt% functionalised CNT was dispersed in epoxy, hardener added and the composite was cured. In the masterbatch approach, 1 wt% functionalised CNT were mixed with epoxy in the presence of triethylamine accelerator, then cured. This yielded partially-cured epoxy; additional hardener was required to Page 2 of 27 achieve complete curing. Improvements were observed in storage modulus (E′) flexural modulus (EB), wear resistance and hardness were also improved. Thermal stability did not change appreciably for samples prepared by either the standard or masterbatch methods. Variations in the results obtained as a function of preparation method, functionalised CNT a...
Irish Journal of Paramedicine
BackgroundThe unpredictability of the nature of the next call is a basic feature of Emergency Ser... more BackgroundThe unpredictability of the nature of the next call is a basic feature of Emergency Services; the call could vary from a trauma victim, to a hypothermic patient or a prehospital birth. All patients (other than those who are pyrexic) have in common the need for a warm environment to prevent deterioration in their condition. Multiple observation studies found that patients suffering from various levels of trauma, arrived in the Emergency Department with hypothermia. Hypothermia, a core temperature…
European Journal of Inorganic Chemistry
European Journal of Physics
This topical review will provide a survey of the current state of the art in 'hyphenated' techniq... more This topical review will provide a survey of the current state of the art in 'hyphenated' techniques for characterisation of bulk materials, surface, and interfaces, whereby two or more analytical methods investigating different properties are applied simultaneously to the same sample to better characterise the sample than can be achieved by conducting separate analyses in series using different instruments. It is intended for final year undergraduates and recent graduates, who may have some background knowledge of standard analytical techniques, but are not familiar with 'hyphenated' techniques or hybrid instrumentation. The review will begin by defining 'complementary', 'hybrid' and 'hyphenated' techniques, as there is not a broad consensus among analytical scientists as to what each term means. The motivating factors driving increased development of hyphenated analytical methods will also be discussed. This introduction will conclude with a brief discussion of gas chromatography-mass spectroscopy and energy dispersive X-ray analysis (EDX) in electron microscopy as two examples, in the context that combining complementary techniques for chemical analysis were among the earliest examples of hyphenated characterisation methods. The emphasis of the main review will be on techniques which are sufficiently well-established that the instrumentation is commercially available, to examine physical properties including physical, mechanical, electrical and thermal, in addition to variations in composition, rather than methods solely to identify and quantify chemical species. Therefore, the proposed topical review will address three broad categories of techniques that the reader may expect to encounter in a well-equipped materials characterisation laboratory: microscopy based techniques, scanning probe based techniques, and thermal analysis based techniques. Examples drawn from recent literature, and a concluding case study, will be used to explain the practical issues that arise in combining different techniques. We will consider how the complementary and varied information obtained by combining these techniques may be interpreted together to better understand the sample in greater detail than that was possible before, and also how combining different techniques can simplify sample preparation and ensure reliable comparisons are made between multiple analyses on the same samples-a topic of particular importance as nanoscale technologies become more prevalent in applied and industrial research and development. The review will conclude with a brief outline of the emerging state of the art in the research laboratory, and a suggested approach to using hyphenated techniques, whether in the teaching, quality control or research and development laboratory.
Composites Science and Technology, Jun 1, 2007
This paper reports a 4.5 fold increase in the Young&#... more This paper reports a 4.5 fold increase in the Young's modulus of a semi-crystalline polymer, poly(vinyl alcohol), with the addition of carbon nanotubes. The importance of nanotube diameter is addressed with the production of four composite solutions with each solution containing ...
Magnetic Resonance in Chemistry, 2005
High-resolution 1 H and 15 Nf 1 Hg solid-state NMR experiments were conducted on two ureidopyrimi... more High-resolution 1 H and 15 Nf 1 Hg solid-state NMR experiments were conducted on two ureidopyrimidinone model compounds: dimeric 2-butylureido-6-methyl-4-pyrimidinone (1) and its bifunctional analogue N,N-1,6-hexanediyl(2-ureido-6-methyl-4-pyrimidinone) (4). High magic angle spinning rates and 1 H decoupling schemes were used to increase the proton spectral resolution. Upon heating 1 to 440 K, an increase in mobility was observed for non-hydrogen-bonded protons; the dimer remained in keto tautomeric form, which is capable of much stronger intermolecular hydrogen bonding than the enol tautomer. From these findings, it was concluded that this ureidopyrimidinone moiety should allow the design of strongly bonded molecular assemblies whose thermal stability compares favourably with that of conventional engineering polymers.
ACS Applied Materials & Interfaces, 2015
Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two... more Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two methods, the layer-by-layer (LBL) assembly technique by employing a pentaerythritol-based ruthenium(II) metallodendrimer as a cationic moiety and also by entrapping the POM in a conducting polypyrrole film. The redox behavior of the constructed films was studied by using cyclic voltammetry and electrochemical impedance spectroscopy. The surface morphologies of the constructed multilayers were examined by scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy was conducted to confirm the elements present within the fabricated films. The multilayer assembly was also investigated for its catalytic efficiency towards the reduction of nitrite.
European Journal of Physics, 2015
Encyclopedia of Polymeric Nanomaterials, 2013
Electrochimica Acta, 2015
Keywords: polyoxometalate electrocatalysis layer-by-layer transition metal ion-substituted crownt... more Keywords: polyoxometalate electrocatalysis layer-by-layer transition metal ion-substituted crowntype polyoxometalate nitrite reduction
ACS Applied Materials & Interfaces, 2015
Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two... more Surface anchoring of an organic functionalized POM, TBA3K[SiW10O36(PhPO)2] was carried out by two methods, the layer-by-layer (LBL) assembly technique by employing a pentaerythritol-based ruthenium(II) metallodendrimer as a cationic moiety and also by entrapping the POM in a conducting polypyrrole film. The redox behavior of the constructed films was studied by using cyclic voltammetry and electrochemical impedance spectroscopy. The surface morphologies of the constructed multilayers were examined by scanning electron microscopy and atomic force microscopy. X-ray photoelectron spectroscopy was conducted to confirm the elements present within the fabricated films. The multilayer assembly was also investigated for its catalytic efficiency towards the reduction of nitrite.
A tetra Ru-substituted polyoxometalate Na10[{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2] (Ru4POM) has been su... more A tetra Ru-substituted polyoxometalate Na10[{Ru4O4(OH)2(H2O)4}(γ-SiW10O36)2] (Ru4POM) has been successfully immobilised onto glassy carbon electrodes and indium tin oxide (ITO) coated glass slides through the employment of a conducting polypyrrole matrix and the layer-by-layer (LBL) technique. The resulting Ru4POM doped polypyrrole films showed stable redox behavior associated with the Ru centres within the Ru4POM, whereas, the POM's tungsten-oxo redox centres were not accessible. The films showed pH dependent redox behavior within the pH range 2-5 whilst exhibiting excellent stability towards redox cycling. The layer-by-layer assembly was constructed onto poly(diallyldimethylammonium chloride) (PDDA) modified carbon electrodes by alternate depositions of Ru4POM and a Ru(II) metallodendrimer. The resulting Ru4POM assemblies showed stable redox behavior for the redox processes associated with Ru4POM in the pH range 2-5. The charge transfer resistance of the LBL films was calculated through AC-Impedance. Surface characterization of both the polymer and LBL Ru4POM films was carried out using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Initial investigations into the ability of the Ru4POM LBL films to electrocatalytically oxidise water at pH 7 have also been conducted.
The Analyst
A conducting polymer was used for the immobilization of various transition metal ion-substituted ... more A conducting polymer was used for the immobilization of various transition metal ion-substituted Dawson-type polyoxometalates (POMs) onto glassy carbon electrodes. Voltammetric responses of films of different thicknesses were stable within the pH domain 2-7 and reveal redox processes associated with the conducting polymer, the entrapped POMs and incorporated metal ions. The resulting POM doped polypyrrole films were found to be extremely stable towards redox switching between the various redox states associated with the incorporated POM. An amperometric sensor for hydrogen peroxide detection based upon the POM doped polymer films was investigated. The detection limits were 0.3 and 0.6 μM, for the Cu(2+)- and Fe(3+)-substituted POM-doped polypyrrole films respectively, with a linear region from 0.1 up to 2 mM H(2)O(2). Surface characterization of the polymer films was carried out using atomic force microscopy, X-ray photoelectron spectroscopy and scanning electron microscopy.
Polymer International, 2009
... Editorial. In Focus: Advances in Epoxy Chemistry. Gordon Armstrong Organisers Advances in E... more ... Editorial. In Focus: Advances in Epoxy Chemistry. Gordon Armstrong Organisers Advances in Epoxy Chemistry June 2009 1,* ,; David Birkett Organisers Advances in Epoxy Chemistry June 2009 2. Article first published online: 13 AUG 2009. DOI: 10.1002/pi.2659. ...
Journal of Colloid and Interface Science, 2011
Titania-silver (TiO 2 -Ag) and alumina-silver (Al 2 O 3 -Ag) composite nanoparticles were synthes... more Titania-silver (TiO 2 -Ag) and alumina-silver (Al 2 O 3 -Ag) composite nanoparticles were synthesised by a simple, reproducible, wet chemical method under ambient conditions. The surface of the oxides was modified with oleic acid, which acted as an intermediate between the oxide surface and the silver nanoparticles. The resulting composite nanoparticles were thoroughly characterized by XRD, TEM, XPS, FTIR and TGA to elucidate the mode of assembly of Ag nanoparticles on the oxide surfaces.
Electrochimica Acta
The electrocatalytic ability of the iron-substituted crown-type polyoxometalate (POM) Li4K16[P8W4... more The electrocatalytic ability of the iron-substituted crown-type polyoxometalate (POM) Li4K16[P8W48O184Fe16(OH)28(H2O)4]·66H2O·2KCl (P8W48Fe16) towards the reduction of both nitrite and hydrogen peroxide reduction has been studied in both the solution and immobilized states for the POM. P8W48Fe16 was surface immobilised onto carbon electrode surfaces through employment of the layer-by-layer technique (LBL) using pentaerythritol-based Ru(II)-metallodendrimer [RuD](PF6)8 as the cationic layer within the resulting films. The constructed multilayer films have been extensively studied by various electrochemical techniques and surface based techniques. Cyclic voltammetry and impedance spectroscopy have been utilized to monitor the construction of the LBL film after the deposition of each monolayer. The electrochemical behaviour of both a cationic and anionic redox probes at the LBL films has been undertaken to give indications as to the film's porosity. The elemental composition and th...
Polymer Bulletin, 2012
Current interest in antimicrobial coatings is driven by an urgent need for more effective strateg... more Current interest in antimicrobial coatings is driven by an urgent need for more effective strategies to control microbial infection. In this study, antimicrobial nanoclays were prepared by ion-exchange of sodium montmorillonite (MMT) with silver ions which have been previously reported to exhibit biocidal activity. The extent of ion exchange achieved was estimated by x-ray photoelectron spectroscopy (XPS). The silver-modified nanoclay (AgMMT) fully inhibited growth of Gram negative Escherichia coli DH5α (E. coli) over 24 hours;
Porous silicon is generally achieved through electro-chemical etching or chemical etching of bulk... more Porous silicon is generally achieved through electro-chemical etching or chemical etching of bulk silicon in hydrofluoric acid based solutions. The work presented here explores the effect of a chemical etching process on a metallurgical grade silicon powder. It is found that the metallurgical grade silicon particles contain surface bound impurities that induce a porous structure formation upon reaction with the chemical etchant applied. The correlation between the resultant porous structure formed due to the material composition is examined in detail. The elemental composition is determined using a combination of X-ray Photoelectron Spectroscopy and Time of Flight Secondary Ion Mass Spectroscopy. The porous structure is analysed using Transmission Electron Microscopy and Scanning Electron Microscopy. Three samples of the silicon particles analysed for this study include an un-etched bulk silicon powder sample and two samples of chemically etched powder. Pore formation within the particles is found to be dependent on the presence, dispersion, and local concentration of surface bound impurities within the starting powder.
Polymer International, 2009
BACKGROUND: Carbon nanotubes (CNTs) are fast becoming key components in the production of high-st... more BACKGROUND: Carbon nanotubes (CNTs) are fast becoming key components in the production of high-strength composite materials. Two methods to prepare nanocomposites by covalent bonding between an epoxy matrix and functionalised CNTs that acted as cross-linkers during polymerisation were investigated. RESULTS: In the standard method, 1 wt% functionalised CNTs was dispersed in epoxy, hardener was added and the composite was cured. In the masterbatch approach, 1 wt% functionalised CNTs was mixed with epoxy in the presence of triethylamine accelerator, then cured. This yielded partially cured epoxy; additional hardener was required to achieve complete curing. Improvements were observed in storage modulus (E ), flexural modulus (E B ), wear resistance and hardness. Thermal stability did not change appreciably for samples prepared by either the standard or masterbatch methods. Variations in the results obtained as a function of preparation method, functionalised CNTs and hardener used are discussed.