Jurewicz I, King AAK, Worajittiphon P, Asanithi P, Brunner EW, Sear RP, Hosea TJC, Keddie JL, Dalton AB (2010) Colloid-Assisted Self-Assembly of Robust, Three-Dimensional Networks of Carbon Nanotubes over Large Areas, MACROMOLECULAR RAPID COMMUNICATIONS 31 (7) pp. 609-615 WILEY-V C H VERLAG GMBH
Asanithi P, Saridakis E, Govada L, Jurewicz I, Brunner EW, Ponnusamy R, Cleaver JAS, Dalton AB, Chayen NE, Sear RP (2009) Carbon-Nanotube-Based Materials for Protein Crystallization,ACS APPL MATER INTER 1 (6) pp. 1203-1210
AMER CHEMICAL SOC
We report on the first use OF carbon-nanotube-based films to produce crystals of proteins. The crystals nucleate on the surface of the film. The difficulty of crystallizing proteins is a major bottleneck in. the determination of the structure and function of biological molecules. The crystallization of two model proteins and two medically relevant proteins was studied. Quantitative data on the crystallization times of the model protein lyozyme are also presented. Two types of nanotube films, one made with the surfactant Triton X-100 (TX-100) and one with gelatin, were tested. Both induce nucleation of the crystal phase at supersaturations at which the protein solution would otherwise remain clear: however, the gelatin-based film induced nucleation down to much lower supersaturations for the two model proteins with which it was used. it appears that the interactions of gelatin with the protein molecules are particularly favorable to nucleation. Crystals of the C I domain of the human cardiac myosin-binding protein-C that diffracted to a resolution of 1.6 angstrom were obtained on the TX-100 film. This is far superior to the best crystals obtained using standard techniques, which only diffracted to 3.0 angstrom. Thus, both of our nanotube-based films are very promising candidates for future work on crystallizing difficult-to-crystallize target proteins.
Worajittiphon P, Jurewicz I, King AA, Keddie JL, Dalton AB (2010) Enhanced thermal actuation in thin polymer films through particle nano-squeezing by carbon nanotube belts., Adv Mater 22 (46) pp. 5310-5314
Boland CS, Khan U, Backes C, O'Neill A, McCauley J, Duane S, Shanker R, Liu Y, Jurewicz I, Dalton AB, Coleman JN (2014) Sensitive, high-strain, high-rate bodily motion sensors based on graphene-rubber composites., ACS Nano 8 (9) pp. 8819-8830
Monitoring of human bodily motion requires wearable sensors that can detect position, velocity and acceleration. They should be cheap, lightweight, mechanically compliant and display reasonable sensitivity at high strains and strain rates. No reported material has simultaneously demonstrated all the above requirements. Here we describe a simple method to infuse liquid-exfoliated graphene into natural rubber to create conducting composites. These materials are excellent strain sensors displaying 10(4)-fold increases in resistance and working at strains exceeding 800%. The sensitivity is reasonably high, with gauge factors of up to 35 observed. More importantly, these sensors can effectively track dynamic strain, working well at vibration frequencies of at least 160 Hz. At 60 Hz, we could monitor strains of at least 6% at strain rates exceeding 6000%/s. We have used these composites as bodily motion sensors, effectively monitoring joint and muscle motion as well and breathing and pulse.
Ultrasonication is the most widely used technique for the dispersion of a range of nanomaterials, but the intrinsic mechanism which leads to stable solutions is poorly understood with procedures quoted in the literature typically specifying only extrinsic parameters such as nominal electrical input power and exposure time. Here we present new insights into the dispersion mechanism of a representative nanomaterial, single-walled carbon nanotubes (SW-CNTs), using a novel up-scalable sonoreactor and an in situ technique for the measurement of acoustic cavitation activity during ultrasonication. We distinguish between stable cavitation, which leads to chemical modification of the surface of the CNTs, and inertial cavitation, which favors CNT exfoliation and length reduction. Efficient dispersion of CNTs in aqueous solution is found to be dominated by mechanical forces generated via inertial cavitation, which in turn depends critically on surfactant concentration. This study highlights that careful measurement and control of cavitation rather than blind application of input power is essential in the large volume production of nanomaterial dispersions with tailored properties.
Heister E, Brunner EW, Dieckmann GR, Jurewicz I, Dalton AB (2013) Are carbon nanotubes a natural solution? Applications in biology and medicine., ACS Appl Mater Interfaces 5 (6) pp. 1870-1891
Carbon nanotubes and materials based on carbon nanotubes have many perceived applications in the field of biomedicine. Several highly promising examples have been highlighted in the literature, ranging from their use as growth substrates or tissue scaffolds to acting as intracellular transporters for various therapeutic and diagnostic agents. In addition, carbon nanotubes have a strong optical absorption in the near-infrared region (in which tissue is transparent), which enables their use for biological imaging applications and photothermal ablation of tumors. Although these advances are potentially game-changing, excitement must be tempered somewhat as several bottlenecks exist. Carbon nanotube-based technologies ultimately have to compete with and out-perform existing technologies in terms of performance and price. Moreover, issues have been highlighted relating to toxicity, which presents an obstacle for the transition from preclinical to clinical use. Although many studies have suggested that well-functionalized carbon nanotubes appear to be safe to the treated animals, mainly rodents, long-term toxicity issues remains to be elucidated. In this report, we systematically highlight some of the most promising biomedical application areas of carbon nanotubes and review the interaction of carbon nanotubes with cultured cells and living organisms with a particular focus on in vivo biodistribution and potential adverse health effects. To conclude, future challenges and prospects of carbon nanotubes for biomedical applications will be addressed.
Brunner EW, Jurewicz I, Heister E, Fahimi A, Bo C, Sear RP, Donovan PJ, Dalton AB (2014) Growth and proliferation of human embryonic stem cells on fully synthetic scaffolds based on carbon nanotubes., ACS Appl Mater Interfaces 6 (4) pp. 2598-2603
Here we show an industrially scalable and inexpensive method of fabricating entirely synthetic, non-xenogeneic carbon nanotube-based scaffolds by vacuum filtration for the culture of human embryonic stem cells. We show that controlled exposure of carbon nanotubes to sonication and the amount of energy delivered to the dispersion directly impacts the surface properties, allowing for control over the nanotopography of the resulting carbon nanotube films, which in turn has demonstrable effects upon in vitro human embryonic stem cells cultures. By altering the nanotube processing conditions before film fabrication, it is possible to influence cell adherence, proliferation and colony morphology. Such a tunable surface with capabilities of influencing stem cell behaviors, combined with the ability to slow or speed population doubling times, will provide crucial solutions for achieving applications envisioned by stem cell biologists to assist future industrial and clinical implementation of human embryonic stem cells.
We highlight the significance of capillary pressure in the directed assembly of nanorods in ordered arrays of colloidal particles. Specifically, we discuss mechanisms for the assembly of carbon nanotubes at the interstitial sites between latex polymer particles during composite film formation. Our study points to general design rules to be considered to optimize the ordering of nanostructures within such polymer matrices. In particular, gaining an understanding of the role of capillary forces is critical. Using a combination of electron microscopy and atomic force microscopy, we show that the capillary forces acting on the latex particles during the drying process are sufficient to bend carbon nanotubes. The extent of bending depends on the flexural rigidity of the carbon nanotubes and whether or not they are present as bundled ensembles. We also show that in order to achieve long-range ordering of the nanotubes templated by the polymer matrix, it is necessary for the polymer to be sufficiently mobile to ensure that the nanotubes are frozen into the ordered network when the film is formed and the capillary forces are no longer dominant. In our system, the polymer is plasticized by the addition of surfactant, so that it is sufficiently mobile at room temperature. Interestingly, the carbon nanotubes effectively act as localized pressure sensors, and as such, the study agrees well with previous theoretical predictions calculating the magnitude of capillary forces during latex film formation.
Jurewicz I, Worajittiphon P, King AA, Sellin PJ, Keddie JL, Dalton AB (2011) Locking carbon nanotubes in confined lattice geometries--a route to low percolation in conducting composites., J Phys Chem B 115 (20) pp. 6395-6400
A significant reduction in the electrical percolation threshold is achieved by locking carbon nanotubes (CNTs) in a predominantly hexagonally close-packed (HCP) colloidal crystal lattice of partially plasticized latex particles. Contrary to other widely used latex processing where CNTs are randomly distributed within the latex matrix, for the first time, we show that excluding CNTs from occupying the interior volume of the latex particles promotes the formation of a nonrandom segregated network. The electrical percolation threshold is four times lower in an ordered segregated network made with colloidal particles near their glass transition temperature (T(g)) in comparison to in a random network made with particles at a temperature well above the T(g). This method allows for a highly reproducible way to fabricate robust, stretchable, and electrically conducting thin films with significantly improved transparency and lattice percolation at a very low CNT inclusion which may find applications in flexible and stretchable electronics as well as other stretchable technologies. For instance, our technology is particularly apt for touch screen applications, where one needs homogeneous distribution of the conductive filler throughout the matrix.
Dalton A, Jurewicz I (2007) Processing - Nanotechnology meets bubbleology, NATURE NANOTECHNOLOGY 2 (6) pp. 339-340 NATURE PUBLISHING GROUP
Cann M, Large MJ, Henley SJ, Milne D, Sato T, Chan H, Jurewicz I, Dalton AB (2016) High performance transparent multi-touch sensors based on silvernanowires, Materials Today Communications 7 pp. 42-50 Elsevier
Silver nanowire networks emerged recently as a remarkable substitute for indium tin oxide (ITO) trans-parent electrodes. Here we show that this silver nanowire alternative can be successfully processed using the same laser ablation technique commonly used to manufacture ITO devices. As a proof of concept, we have manufactured a fully operating five inch multi-touch highly-pixelated sensor typically used in smartphone technology and find it to perform comparably to one based on ITO. We observe that laser processing silver nanowire films is much more efficient from an energy point of view, with scribes hardly visible to the naked eye. We find that the sheet resistance (RS) of the nanowire films increases as a result of dividing it into finite geometries and supported by simulation data, we predict over which length scales this affect becomes significant. Our results point to the viability of using such nanowire systems as an alternative to more traditional technologies in touch sensor design while highlighting some of the challenges to be addressed.
Fahimi A, Jurewicz I, Smith RJ, Sharrock CS, Bradley DA, Henley SJ, Coleman JN, Dalton AB (2013) Density controlled conductivity of pristine graphene films, Carbon 64 pp. 435-443
Single or few layer graphene can be considered an exciting pseudo-two-dimensional molecular material that potentially has a wide range of applications. A critical bottleneck may arise with issues in their controlled assembly into macroscopic ensembles over large areas both in two and three dimensions. Langmuir-type assembly is a particularly useful method to control and manipulate the distribution of graphene at the air-water interface via edge-edge interactions. In this study, pristine graphene suspended in organic solvent was prepared through adaptation of a previously developed process involving the non-invasive exfoliation of graphite. Successful deposition of graphene at the air-water interface was achieved by manipulating the vapor-pressure of the graphene dispersion through solvent mixing. Through careful control of density, by following the pressure-area isotherm during monolayer compression, it is possible to precisely tune the electrical conductivity. The resulting assemblies can be easily transferred to glass and other substrates using the Langmuir-Schaefer horizontal deposition method producing thin films with tunable electrical conductivity that exhibits percolation-type behavior. A major advantage of this process is that the conducting films require no further treatment unlike their graphene-oxide counterparts. Moreover, the physical properties of these assemblies can be easily controlled which is a precursor for graphene-based electronic applications. © 2013 Elsevier Ltd. All rights reserved.
Keddie JL, Wang T, Jurewicz I, Dalton AB, Creton C, Manea M, Asua JM (2007) Multifunctional nanocomposites of soft polymer colloids and carbon nanotubes, ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY 234 AMER CHEMICAL SOC
Graphite ion chambers and semiconductor diode detectors have been used to make measurements in phantoms but these active devices represent a clear disadvantage when considered for in vivo dosimetry. In such circumstance, dosimeters with atomic number similar to human tissue are needed. Carbon nanotubes have properties that potentially meet the demand, requiring low voltage in active devices and an atomic number similar to adipose tissue. In this study, single-wall carbon nanotubes (SWCNTs) buckypaper has been used to measure the beta particle dose deposited from a strontium-90 source, the medium displaying thermoluminescence at potentially useful sensitivity. As an example, the samples show a clear response for a dose of 2Gy. This finding suggests that carbon nanotubes can be used as a passive dosimeter specifically for the high levels of radiation exposures used in radiation therapy. Furthermore, the finding points towards further potential applications such as for space radiation measurements, not least because the medium satisfies a demand for light but strong materials of minimal capacitance.
Abdullah CA, Asanithi P, Brunner EW, Jurewicz I, Bo C, Azad CL, Ovalle-Robles R, Fang S, Lima MD, Lepro X, Collins S, Baughman RH, Sear RP, Dalton AB (2011) Aligned, isotropic and patterned carbon nanotube substrates that control the growth and alignment of Chinese hamster ovary cells.,Nanotechnology 22 (20)
Institute of Physics
Here we culture Chinese hamster ovary cells on isotropic, aligned and patterned substrates based on multiwall carbon nanotubes. The nanotubes provide the substrate with nanoscale topography. The cells adhere to and grow on all substrates, and on the aligned substrate, the cells align strongly with the axis of the bundles of the multiwall nanotubes. This control over cell alignment is required for tissue engineering; almost all tissues consist of oriented cells. The aligned substrates are made using straightforward physical chemistry techniques from forests of multiwall nanotubes; no lithography is required to make inexpensive large-scale substrates with highly aligned nanoscale grooves. Interestingly, although the cells strongly align with the nanoscale grooves, only a few also elongate along this axis: alignment of the cells does not require a pronounced change in morphology of the cell. We also pattern the nanotube bundles over length scales comparable to the cell size and show that the cells follow this pattern.
Jurewicz I, Fahimi A, Lyons PE, Smith RJ, Cann M, Large ML, Tian M, Coleman JN, Dalton AB (2014) Insulator-Conductor Type Transitions in Graphene-Modified Silver Nanowire Networks: A Route to Inexpensive Transparent Conductors, ADVANCED FUNCTIONAL MATERIALS 24 (48) pp. 7580-7587 WILEY-V C H VERLAG GMBH
Garriga R, Jurewicz I, Romero E, Jarne C, Cebolla VL, Dalton AB, Munoz E (2016) Two-Dimensional, pH-Responsive Oligoglycine-Based Nanocarriers, ACS APPLIED MATERIALS & INTERFACES 8 (3) pp. 1913-1921 AMER CHEMICAL SOC
The nanocarrier capabilities of atomically smooth two-dimensional sheets of a biantennary oligoglycine peptide C8H16(?CH2?NH?Gly5)2 (also called tectomers) are demonstrated. We show that the pH-controlled, rapid, and reversible assembly and disassembly of oligoglycine can be effectively used for controlled loading and release of the anticancer drug and fluorescent probe coralyne. The calculated partition coefficient in water is of the same order of magnitude or higher when compared to other nanocarriers such as liposomes and micelles, signifying the tectomer?s impressive loading capabilities. Moreover, the loading of guest molecules in tectomers facilitates the protection from rapid photochemically induced degradation. Such efficient, pH-sensitive, stable, and biocompatible nanocarriers are extremely attractive for biosensing, therapeutic, and theranostic applications. Additionally, our results suggest that these planar self-assembled materials can also act as phase-transfer vehicles for hydrophobic cargoes further broadening their biomedical and technological applications.
Henley SJ, Cann M, Jurewicz I, Dalton A, Milne D (2014) Laser patterning of transparent conductive metal nanowire coatings: simulation and experiment., Nanoscale 6 (2) pp. 946-952
Transparent and electrically conductive metal nanowire networks are possible replacements for costly indium tin oxide (ITO) films in many optoelectronic devices. ITO films are regularly patterned using pulsed lasers so similar technologies could be used for nanowire coatings to define electrode structures. Here, the effects of laser irradiation on conducting silver nanowire coatings are simulated and then investigated experimentally for networks formed by spray deposition onto transparent substrates. The ablation threshold fluence is found experimentally for such nanowire networks and is then related to film thickness. An effective model using finite-element heat transfer analysis is examined to look at energy dissipation through these nanowire networks and used to understand mechanisms at play in the laser-material interactions. It is demonstrated that the three-dimensional nature of these coatings and the relative ratios of the rates of lateral to vertical heat diffusion are important controlling parameter affecting the ablation threshold.
Brunner EW, Jurewicz I, Heister E, Fahimi A, Bo C, Sear RP, Dalton AB, Donovan PJ (2014) Growth and proliferation of human embryonic stem cells on fully synthetic scaffolds based on carbon nanotubes, ACS Applied Materials and Interfaces 6 (4) pp. 2598-2603
Here we show an industrially scalable and inexpensive method of fabricating entirely synthetic, non-xenogeneic carbon nanotube-based scaffolds by vacuum filtration for the culture of human embryonic stem cells. We show that controlled exposure of carbon nanotubes to sonication and the amount of energy delivered to the dispersion directly impacts the surface properties, allowing for control over the nanotopography of the resulting carbon nanotube films, which in turn has demonstrable effects upon in vitro human embryonic stem cells cultures. By altering the nanotube processing conditions before film fabrication, it is possible to influence cell adherence, proliferation and colony morphology. Such a tunable surface with capabilities of influencing stem cell behaviors, combined with the ability to slow or speed population doubling times, will provide crucial solutions for achieving applications envisioned by stem cell biologists to assist future industrial and clinical implementation of human embryonic stem cells. © 2014 American Chemical Society.
Garriga R, Jurewicz Izabela, Seyedin S, Bardi Niki, Totti Styliani, Matta? Domjan B, Velliou Eirini, Alkhorayef Mohammed, Cebolla VL, Razal JM, Dalton Alan, Muñoz E (2017) Multifunctional, Biocompatible and pH-Responsive Carbon Nanotube- and Graphene Oxide/Tectomer Hybrid Composites and Coatings,Nanoscale 9 pp. 7791-7804
Royal Society of Chemistry
Here we present a route for non?covalent functionalization of carboxylated multi?wall carbon nanotubes and graphene oxide with novel two?dimensional peptide assemblies. We show that self?assembled amino?terminated biantennary and tetraantennary oligoglycine peptides (referred to as tectomers) effectively coat carboxylated multi?walled carbon nanotubes and also strongly interact with graphene oxide due to electrostatic interactions and hydrogen bonding as the driving force, respectively. The resulting hybrids can be made into free?standing conducting composites or applied in the form of thin, pH?switchable bioadhesive coatings onto graphene oxide fibers. Monitoring of cell viability of pancreatic cell lines, seeded on those CNT hybrids, show that they can be used as two? and three?dimensional scaffolds to tissue engineer tumour models for studying ex vivo the tumour development and response to treatment. This highly versatile method in producing pH?responsive hybrids and coatings offers an attractive platform for a variety of biomedical applications and for the development of functional materials such as smart textiles, sensors and bioelectronic devices.
We demonstrate that the optoelectronic properties of percolating thin films of silver nanowires (AgNWs) are
predominantly dependent upon the length distribution of the constituent AgNWs. A generalized expression is
derived to describe the dependence of both sheet resistance and optical transmission on this distribution. We
experimentally validate the relationship using ultrasonication to controllably vary the length distribution.
These results have major implications where nanowire-based films are a desirable material for transparent
conductor applications; in particular when application-specific performance criteria must be met. It is of
particular interest to have a simple method to generalize the properties of bulk films from an understanding of
the base material, as this will speed up the optimisation process. It is anticipated that these results may aid in
the adoption of nanowire films in industry, for applications such as touch sensors or photovoltaic electrode
We report the first application of finite-size scaling theory to nanostructured percolating networks, using silver nanowire (AgNW) films as a model system for experiment and simulation. AgNWs have been shown to be a prime candidate for replacing Indium Tin Oxide (ITO) in applications such as capacitive touch sensing. While their performance as large area films is well-studied, the production of working devices involves patterning of the films to produce isolated electrode structures, which exhibit finite-size scaling when these features are sufficiently small. We demonstrate a generalised method for understanding this behaviour in practical rod percolation systems, such as AgNW films, and study the effect of systematic variation of the length distribution of the percolating material. We derive a design rule for the minimum viable feature size in a device pattern, relating it to parameters which can be derived from a transmittance? sheet resistance data series for the material in question. This understanding has direct implications for the industrial adoption of silver nanowire electrodes in applications where small features are required including single-layer capacitive touch sensors, LCD and OLED display panels
Dosimetry devices based on Carbon Nanotubes are a promising new technology. In particular using devices based on single wall carbon nanotubes may offer a tissue equivalent response with the possibility for device miniaturisation, high scale manufacturing and low cost. An important precursor to device fabrication requires a quantitative study of the effects of X-ray radiation on the physical and chemical properties of the individual nanotubes. In this study, we concentrate on the effects of relatively low doses, 20 cGy and 45 cGy, respectively. We use a range of characterization techniques including scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy to quantify the effects of the radiation dose on inherent properties of the nanotubes. Specifically we find that the radiation exposure results in a reduction in the sp2 nature of the nanotube bond structure. Moreover, our analysis indicates that the exposure results in nanotubes that have an increased defect density which ultimately effects the electrical properties of the nanotubes.
Matta-Domjan Brigitta, King Alice, Totti Stella, Matta Csaba, Dover George, Martinez Patricia, Zakhidov Anvar, La Ragione Roberto, Macedo Hugo, Jurewicz Izabela, Dalton Alan, Velliou Eirini (2017) Biophysical interactions between pancreatic adenocarcinoma cell lines and pristine carbon nanotube substrates: Potential application for pancreatic cancer tissue engineering,Journal of Biomedical Materials Research Part B-Applied Biomaterials 106 (5) pp. 1637-1644
Novel synthetic biomaterials able to support, direct tissue growth and retain cellular phenotypical properties are promising building blocks for the development of tissue engineering platforms for accurate and fast therapy screening for cancer. The aim of this study is to validate an aligned, pristine multi-walled carbon nanotube (CNT) platform for in vitro studies of pancreatic cancer as a systematic understanding of interactions between cells and these CNT substrates is lacking. Our results demonstrate that our CNT scaffolds -which are easily tuneable to form sheets/fibres- support growth, proliferation and spatial organisation of pancreatic cancer cells, indicating their great potential in cancer tissue engineering.
Large Matthew, Ogilvie Sean, Alomairy Sultan, Vockerodt Terence, Myles David, Cann Maria, Chan Helios, Jurewicz Izabela, King Alice, Dalton Alan (2017) Selective mechanical transfer deposition of Langmuir graphene films for high-performance silver nanowire hybrid electrodes,Langmuir 33 (43) pp. 12038-12045
American Chemical Society
In this work we present silver nanowire hybrid electrodes, prepared through the
addition of small quantities of pristine graphene by mechanical transfer deposition from
surface-assembled Langmuir films. This technique is a fast, efficient, and facile method
for modifying the opto-electronic performance of AgNW films. We demonstrate that
it is possible to use this technique to perform two-step device production by selective
patterning of the stamp used, leading to controlled variation in the local sheet resistance
across a device. This is particularly attractive for producing extremely low-cost sensors
on arbitrarily large scales. Our aim is to address some of the concerns surrounding
the use of AgNW films as replacements for indium tin oxide (ITO); namely the use of scarce materials and poor stability of AgNWs against flexural and environmental
King Alice A. K., Matta-Domjan Brigitta, Large Matthew J., Matta Csaba, Ogilvie Sean P., Bardi Niki, Byrne Hugh J., Zakhidov Anvar, Jurewicz Izabela, Velliou Eirini, Lewis Rebecca, La Ragione Roberto, Dalton Alan (2017) Pristine carbon nanotube scaffolds for the growth of chondrocytes,Journal of Materials Chemistry B 5 (41) pp. 8178-8182
Royal Society of Chemistry
The effective growth of chondrocytes and the formation of cartilage is demonstrated on scaffolds of aligned carbon nanotubes; as two dimensional sheets and on three dimensional textiles. Raman spectroscopy is used to confirm the presence of chondroitin sulfate, which is critical in light of the unreliability of traditional dye based assays for carbon nanomaterial substrates. The textile exhibits a very high affinity for chondrocyte growth and could present a route to implantable, flexible cartilage scaffolds with tuneable mechanical properties.
Nanoparticles of cerium dioxide (or nanoceria) are of interest because of their oxygen buffering, photocatalytic ability, and high UV absorption. For applications, the nanoceria can be incorporated in a polymer binder, but questions remain about the link between the nanoparticle distribution and the resulting nanocomposite properties. Here, the thermal, mechanical and optical properties of polymer/ceria nanocomposites are correlated with their nanostructures. Specifically, nanocomposites made from waterborne Pickering particles with nanoceria shells are compared to nanocomposites made from blending the equivalent surfactant-free copolymer particles with nanoceria. Two types of nanoceria (protonated or citric acid-coated) are compared in the Pickering particles. A higher surface coverage is obtained with the protonated ceria, which results in a distinct cellular structure with nanoceria walls within the nanocomposite. In the blend of particles, a strong attraction between the protonated nanoceria and the acrylic acid groups of the copolymer likewise leads to a cellular structure. This structure offers transparency in the visible region combined with strong UV absorption, which is desired for UV blocking coating applications. Not having an attraction to the polymer, the citric acid-coated nanoceria forms agglomerates that lead to undesirable light scattering in the nanocomposite and yellowing. This latter type of nanocomposite coating is less effective in protecting substrates from UV damage but provides a better barrier to water. This work shows how the nanoparticle chemical functionalization can be used to manipulate the structure and to tailor the properties of UV-absorbing barrier coatings.
Jurewicz Izabela, Garriga Rosa, Large Matthew J, Burn Jake, Bardi Niki, King Alice AK, Velliou Eirini, Watts John, Hinder Steven, Muñoz Edgar, Dalton Alan B (2018) Functionalization of Silver Nanowire Transparent Electrodes with Self-Assembled 2-Dimensional Tectomer Nanosheets,ACS Applied Nano Materials 1 (8) pp. 3903-3912
American Chemical Society
Here, we describe the unusual self-assembly of amine-terminated oligoglycine peptides into extended two-dimensional sheets in the presence of silver nanowires. The resulting tectomer sheets are shown to have a strong affinity for the nanowires through a charge-transfer interaction as evidenced by X-ray photoelectron spectroscopy. We show that extended assemblies of metal-peptide hybrids offer additional augmentative functionalities, for instance, the tectomer sheets are hydrophobic in nature and act as a protective layer preventing oxidation and degradation of the nanowires when exposed to atmospheric conditions. Moreover, for silver nanowire percolating networks the presence of the peptide markedly increases the overall electrical conductivity through mechanical squeezing of wire-wire junctions in the network. The peptide-metal interface can be controlled by pH stimulus thus potentially offering new directions where silver nanowire assemblies are used for transparent electrodes ranging from antimicrobial coatings to biosensors.
Amino-terminated oligoglycine two-dimensional (2D) peptide self-assemblies (known as tectomers) have a versatile surface chemistry that allows them to interact with a variety of nanomaterials and to act as supramolecular adhesives for surface functionalization. Here, we have exploited the strong hydrogen-bond based interaction between tectomers and graphene oxide (GO) to functionalize GO fiber surfaces with different carbon nanomaterials (carbon nanotubes, carbon nanohorns, carbon nanocones, and highly fluorescent nanodiamonds), metal (gold, platinum, iron) nanoparticles, acrylate-based polymer nanoparticles, fluorophores and drugs. The resulting ultrathin coatings exhibit remarkable water resistant properties. This tectomer-mediated fiber decoration strategy allows coating functionalities to be tailored by choosing the appropriate nanomaterials or other molecules. We show that this strategy can be extended to other fibers and fabrics, such as polyurethane/PEDOT:PSS, poly(methyl methacrylate) and polyester, making it very attractive for a variety of technological and smart textile applications.
Jurewicz Izabela, King Alice A.K, Shanker Ravi, Large Matthew J., Smith Roman J., Maspero Ross, Ogilvie Sean P., Scheerder Jurgen, Han Jun, Backes Claudia, Razal Joe, Florescu Marian, Keddie Joseph, Coleman Jonathan N., Dalton Alan (2020) Mechanochromic and Thermochromic Sensors Based on Graphene Infused Polymer Opals,Advanced Functional Materials 30 (31)
High quality opal-like photonic crystals containing graphene are fabricated using evaporation-driven self-assembly of soft polymer colloids. A miniscule amount of pristine graphene within a colloidal crystal lattice results in the formation of colloidal crystals with a strong angle-dependent structural color and a stop band that can be reversibly shifted across the visible spectrum. The crystals can be mechanically deformed or can reversibly change color as a function of their temperature, hence their sensitive mechanochromic and thermochromic response make them attractive candidates for a wide range of visual sensing applications. In particular, we show that the crystals are excellent candidates for visual strain sensors or integrated time-temperature indicators which act over large temperature windows. Given the versatility of these crystals, this method represents a simple, inexpensive and scalable approach to produce multifunctional graphene infused synthetic opals and opens up exciting applications for novel solution-processable nanomaterial based photonics.
O'Mara Marcus A., Ogilvie Sean P., Large Matthew J., Salvage Jonathan P., Graf Aline Amorim, Sehnal Anne C., Lynch Peter J., Jurewicz Izabela, King Alice A.K, Dalton Alan B. (2020) Ultra-Sensitive Strain Gauges Enabled by Graphene-Stabilized Silicone Emulsions,Advanced Function Materials
Here, we present an approach to incorporate graphene nanosheets into a silicone rubber matrix via
solid stabilization of oil-in-water emulsions. These emulsions can be cured into discrete, graphenecoated
silicone balls or continuous, elastomeric films by controlling the degree of coalescence. We
characterize the electromechanical properties of the resulting composites as a function of
interdiffusion time and graphene loading level. With conductivities approaching 1 S m-1, elongation
to break up to 160% and a gauge factor of ~20 in the low-strain linear regime, we can accurately
measure small strains such as pulse. At higher strains, the electromechanical response exhibits a
robust exponential dependence, allowing accurate readout for higher strain movements such as
chest motion and joint bending. The exponential gauge factor is found to be ~20, independent of
loading level and valid up to 80% strain; this consistent performance is due to the emulsiontemplated
microstructure of the composites. The robust behavior may facilitate high-strain sensing
in the non-linear regime using nanocomposites, where relative resistance change values in excess of
107 enable highly accurate bodily motion monitoring.
Graphene and other graphitic materials are suggested as a route to cheap, high?performance, environmentally?sustainable electronic devices owing to their almost unique combination of properties. Liquid?phase exfoliation is a family of shear?based techniques that produce dispersions of nanosheets from bulk layered material crystallites. High?quality nanosheets of graphene can be produced in solvents or surfactant dispersions; however the lateral size of these sheets limits the network transport properties observed in printed films. A high?throughput, industrially?scalable aqueous process for the production of graphene and related layered nanomaterials is presented. By considering not only the exfoliation process, but also the size selection and deposition processes, printable graphitic nanoparticulate materials with conductivities up to 50 000 S m?1 are demonstrated. This value is ten times larger than is typically obtained for few?layer graphene produced by liquid?phase exfoliation. The size selection process is critical to obtaining the maximum conductivity of deposited films, with an optimized nanographite having greater performance than few?layer graphene or graphite that is processed and used without size selection. Building on these results a radio?frequency antenna application is demonstrated, which is competitive with the state?of?the?art, and a route to recycling of such printed short?lifetime electronic devices to lower the environmental impact is discussed.
Two-dimensional titanium carbide (Ti3C2Tx), or MXene, is a new nanomaterial that has attracted increasing interest due to its metallic conductivity, good solution processability, and excellent energy storage performance. However, Ti3C2Tx MXene flakes suffer from degradation through
oxidation due to prolonged exposure to oxygenated water. Preventing the occurrence of oxidation
i.e. the formation of TiO2 particles, was found to be the crucial to maintain MXene quality. In
present work, we found that freezing aqueous MXene dispersions at low-temperature can effectively prevents the formation of TiO2 nanoparticles at the flake edge, which is known as the early stage of oxidation. The Ti3C2Tx flakes in frozen dispersion remains consistent in morphology
and elemental composition for over 650 days, compared with freshly synthesized MXene; which in contrast, exhibits flake edge degradation within two days when stored at room temperature. This result suggests that freezing MXene dispersion dramatically postpones the oxidation of MXene
flakes and the stored MXene dispersion can be treated as freshly prepared MXene. This work not
only fundamentally fulfilled the study on temperature dependence of MXene oxidation, but has
also demonstrated a simple method to extend the shelf life of MXene aqueous dispersion to years,
which will be a cornerstone for large scale production of MXene and ultimately benefit the
research on MXenes.
Nufer Sebastian, Lynch Peter J., Large Matthew J., Ogilvie Sean P., Salvage Jonathan P., Pelaez-Fernandez Mario, Waters Thomas, Jurewicz Izabela, Muñoz Edgar, Arenal Raul, Benito Ana M., Maser Wolfgang K., Tagmatarchis Nikos, Ewels Christopher P., Brunton Adam, Dalton Alan B. (2020) Laser-Deposited Carbon Aerogel Derived from Graphene Oxide Enables NO2-Selective Parts-per-Billion Sensing,ACS Applied Materials & Interfaces 12 (35) pp. 39541-39548
American Chemical Society
Laser-deposited carbon aerogel is a low-density porous network of carbon clusters synthesized using a laser process. A one-step synthesis, involving deposition and annealing, results in the formation of a thin porous conductive film which can be applied as a chemiresistor. This material is sensitive to NO2 compared to ammonia and other volatile organic compounds and is able to detect ultra-low concentrations down to at least 10 parts-per-billion. The sensing mechanism, based on the solubility of NO2 in the water layer adsorbed on the aerogel, increases the usability of the sensor in practically-relevant ambient environments. A heating step, achieved in tandem with a microheater, allows the recovery to the baseline making it operable in real world environments. The operability at room temperature, its low cost and scalable production makes it promising for Internet-of-Things air quality monitoring.