Publications by authors named "John Texter"

Electrospinning of nanocarbons such as graphene and carbon nanotubes typically produces mats composed of one-dimensional fibers where the carrier polymer encapsulates the nanocarbons. Recently it was found that decreasing the amount of carrier polymer in approaching the electrospinning-electrospray boundary for graphene suspensions resulted in retention of the graphene two-dimensional anisotropy with one-dimensional carrier polymer fibers connecting flakes. We explored a similar decrease in carrier polymer in MWCNT suspensions to investigate the network topology that might ensue.

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The breadth and importance of polymerized ionic liquids (PILs) are steadily expanding, and this review updates advances and trends in syntheses, properties, and applications over the past five to six years. We begin with an historical overview of the genesis and growth of the PIL field as a subset of materials science. The genesis of ionic liquids (ILs) over nano to meso length-scales exhibiting 0D, 1D, 2D, and 3D topologies defines colloidal ionic liquids, CILs, which compose a subclass of PILs and provide a synthetic bridge between IL monomers (ILMs) and micro to macro-scale PIL materials.

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Metal-nitrogen-carbon (M-C/N) electrocatalysts have been shown to have satisfactory catalytic activity and long-term durability for the oxygen reduction reaction (ORR). Here, a strategy to prepare a new electrocatalyst (Fe&Pd-C/N) using a unique metal-containing ionic liquid (IL) is exploited, in which Fe & Pd ions are positively charged species atomically dispersed by coordination to the N of the N-doped C substrate, C/N. X-ray absorption fine structure, XPS and aberration-corrected transmission electron microscopy results verified a well-defined dual-atom configuration comprising Fe -N coupled Pd -N sites and well-defined spatial distribution.

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Since the first intercalation of layered silicates by using supercritical CO as a processing medium, considerable efforts have been dedicated to intercalating and exfoliating layered two-dimensional (2D) materials in various supercritical fluids (SCFs) to yield single- and few-layer nanosheets. Here, recent work in this area is highlighted. Motivating factors for enhancing exfoliation efficiency and product quality in SCFs, mechanisms for exfoliation and dispersion in SCFs, as well as general metrics applied to assess quality and processability of exfoliated 2D materials are critically discussed.

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A polyurethane (PU) resin derived from glycerol and hexamethylene diisocyanate and an imidazolium bromide ionic liquid chain terminator yield a stimuli-responsive resin that reversibly porates as a solvation response.

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The transformation of CO into fuels and chemicals by photocatalysis is a promising strategy to provide a long-term solution to mitigating global warming and energy-supply problems. Achievements in photocatalysis during the last decade have sparked increased interest in using sunlight to reduce CO . Traditional semiconductors used in photocatalysis (e.

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We investigate surface modification by organo-trimethoxysilanes of nano-ceria and if such surface-modified nano-ceria can be transformed into solvent-free nanofluids. We also examine whether simultaneous modification with ionic liquid salts and with acrylate groups yields nanofluids suitable for forming UV-protective films and clear coatings by UV-initiated polymerization. Nominally 3nm diameter CeO was successfully synthesized and surface decorated with an ionic liquid salt and with acrylate groups to produce a core/shell structured solvent-free nanofluid after ion exchange of chloride for a soft polyoxyethylene sulfonate anion.

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We review recent works on the synthesis and application of poly(ionic liquid)s (PILs). Novel chemical structures, different synthetic strategies and controllable morphologies are introduced as a supplement to PIL systems already reported. The primary properties determining applications, such as ionic conductivity, aqueous solubility, thermodynamic stability and electrochemical/chemical durability, are discussed.

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The preparation of dispersions of single- and few-sheet 2D materials in various solvents, as well as the characterization methods applied to such dispersions, is critically reviewed. Motivating factors for producing single- and few-sheet dispersions of 2D materials in liquids are briefly discussed. Many practical applications are expected for such materials that do not require high purity formulations and tight control of donor and acceptor concentrations, as required in conventional Fab processing of semiconductor chips.

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A new polymerized ionic liquid has been derived by photopolymerization of a stimuli-responsive ionic liquid surfactant, ILAMPS, which is composed of polymerizable, paired ions. The cation is 1-methyl-3-[11-(acryloyloxy)undecyl] imidazolium (IL), and the anion is 2-acrylamido-2-methyl-1-propanesulfonate (AMPS). This ion combination is a new ionic liquid.

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Exfoliation of two-dimensional materials is key to obtaining high-performance properties. We present a simple kinetic model for exfoliation that is readily solved analytically. Random and irreversible sheet separation is postulated in the presence of highly effective stabilizers.

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OBJECTIVE. The purpose of this study was to comprehensively study estimated radiation doses for subjects included in the main analysis of the Combined Non-invasive Coronary Angiography and Myocardial Perfusion Imaging Using 320 Detector Computed Tomography (CORE320) study ( ClinicalTrials.gov identifier NCT00934037), a clinical trial comparing combined CT angiography (CTA) and perfusion CT with the reference standard catheter angiography plus myocardial perfusion SPECT.

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We demonstrate essentially complete exfoliation of graphene aggregates in water at concentrations up to 5% by weight (166-fold greater than previous high concentration report) using recently developed triblock copolymers and copolymeric nanolatexes based on a reactive ionic liquid acrylate surfactant. We demonstrate that the visible absorption coefficient in aqueous dispersion, 48.9 ± 1.

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A synergism between methyl methacrylate and an amphiphilic ionic liquid acrylate 1-(11-acryloyloxyundecyl)-3-methyl imidazolium bromide (IL) not only increases the apparent thermal stability (kinetic retardation of thermal decomposition) of poly(MMA--IL) copolymers by 50 °C at relatively low doping levels of 0.5 mol %, but also increases the storage (∼10%) and loss (15-25%) moduli over 0-75 °C (increasing the elasticity). Moderate to high doping levels provide plasticization without the risk of leaching or plasticizer contamination.

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A polymerizable ionic liquid surfactant, 1-(11-acryloyloxyundecyl)-3-methylimidiazolium bromide (ILBr), was copolymerized with methyl methacrylate (MMA) in aqueous microemulsions at 30% (ILBr w/w) and various water to MMA ratios. The ternary phase diagram of the ILBr/MMA/water system was constructed at 25 and 60 °C. Homopolymers and copolymers of ILBr and MMA were produced by thermally initiated chain radical microemulsion polymerization at various compositions in bicontinuous and reverse microemulsion subdomains.

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Autocondensation of organoalkoxysilanes and subsequent anion exchange produces organosiloxane supramolecular liquids which are core-free and solvent-free nanoparticle nanofluids. This hybrid supramolecular liquid, [C(81)H(156)NO(3)S(SiO([2>x>3/2]))](y), exhibits (see TEM image; 200 nm width) interparticle menisci and softness (from imputed deformations) of interparticle potential.

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Small-angle neutron scattering and turbidity were used to probe nanoscale structure in bicontinuous microemulsions before and after polymerization. Difficulties in capturing nanoscale structure by polymerizing microemulsions have persisted with the use of thermal initiation. Bicontinuous microemulsion polymerization with a reactive surfactant monomer and cross-linker was done with only a 20% increase in repeat distance.

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Anion responsive imidazolium-based polymers.

Macromol Rapid Commun

December 2012

Stimuli responsiveness in polymer design is providing basis for diversely new and advanced materials that exhibit switchable porosity in membranes and coatings, switchable particle formation and thermodynamically stable nanoparticle dispersions, polymers that provide directed mechanical stress in response to intensive fields, and switchable compatibility of nanomaterials in changing environments. The incorporation of ionic liquid monomers has resulted in many new polymers based on the imidazolium group. These polymers exhibit all of the above-articulated material properties.

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Background: Appropriate clinical decisions concerning diagnosis and treatment of coronary artery disease rely on correct integration of data on coronary anatomy and myocardial perfusion. The purpose of this article is to introduce a new left ventricular segmentation model for improved alignment of coronary arterial segments and myocardial perfusion territories, designed for the CORE320 study.

Methods And Results: CORE320 is a prospective, multicenter study with a primary objective to evaluate the diagnostic accuracy of 320-row detector computed tomography (CT) to detect coronary artery luminal stenosis and corresponding myocardial perfusion deficits in patients with suspected coronary artery disease compared with the gold standard of conventional coronary angiography and single-photon emission CT myocardial perfusion imaging.

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A new class of very stable and stimuli-responsive nanolatexes based on copolymers of reactive and stimuli responsive ionic liquid surfactants is synthesized by microemulsion polymerization to yield dispersions of 22-30 nm diameter particles. Aqueous coatings of these nanolatexes dry to form robust films that exhibit stimuli-responsiveness to certain ion exchangeable anions. The nature of the reactive ionic liquid surfactant monomers induces an ion exchange capacity in the resulting copolymers and films.

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The controlled atom transfer radical polymerization of an ionic liquid, 1-(11-acryloylundecyl)-3-methyl imidazolium bromide (ILBr), from both ends of a telechelic poly(propylene oxide) (PPO) macroinitiator, end-functionalized with bromoisobutyryloyl is reported. The resulting highly water-soluble triblock, poly(ILBr-b-PO-b-ILBr) is multistimuli responsive. This new class of triblocks exhibits classical surface activity in lowering surface tension at the air-water interface and in modifying wetting in waterborne coatings.

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Thin films of a stimuli-responsive homopolymer dewet as a stimulus response after anion exchange of the imidazolium's counter anion. Contact angle analysis and interfacial energy considerations indicate dewetting goes counter to increasing spreading coefficient. Intrafilm stress arising from structural relaxation drives the dewetting.

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Coronary vessel distensibility is reduced with atherosclerosis and normal aging, but direct measurements have historically required invasive measurements at cardiac catheterization. Therefore, we sought to assess coronary artery distensibility noninvasively using 3.0 Telsa coronary magnetic resonance imaging (MRI) and to test the hypothesis that this noninvasive technique can detect differences in coronary distensibility between healthy subjects and those with coronary artery disease (CAD).

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A stimuli-responsive homopolymer poly(ILBr) is fabricated via a "two-phase" atom transfer radical polymerization (ATRP) process, where ILBr stands for the reactive ionic liquid surfactant, 1-[11-acryloylundecyl]-3-methyl-imidazolium bromide. An extraordinarily wide molecular weight distribution (PDI = 6.0) was obtained by introducing the initiator (4-bromomethyl methyl benzoate) in a heterogeneous two-phase process.

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