This paper provides a review of the recent advances made in the field of electroactive polymers and composites for biomedical applications.
The significant and rapid reduction of greenhouse gas emissions is recognized as necessary to mitigate the potential climate effects from global warming. The postcombustion capture (PCC) and storage of carbon dioxide (CO2) produced from the use of fossil fuels for electricity generation is a key technology needed to achieve these reductions. The most mature technology for CO2 capture is reversible chemical absorption into an aqueous amine solution. In this study the results from measurements of the CO2 absorption capacity of aqueous amine solutions for 76 different amines are presented. Measurements were made using both a novel isothermal gravimetric analysis (IGA) method and a traditional absorption apparatus. Seven amines, consisting of one primary, three secondary, and three tertiary amines, were identified as exhibiting outstanding absorption capacities. Most have a number of structural features in common including steric hindrance and hydroxyl functionality 2 or 3 carbons from the nitrogen. Initial CO2 absorption rate data from the IGA measurements was also used to indicate relative absorption rates. Most of the outstanding performers in terms of capacity also showed initial absorption rates comparable to the industry standard monoethanolamine (MEA). This indicates, in terms of both absorption capacity and kinetics, that they are promising candidates for further investigation.
Quartz crystal impedance analysis has been developed as, with concentration varied using methanol, was tested and also found to provide a Newtonian response. In both cases, the values of the square root of the viscositydensity product deduced from the small-volume quartz crystal technique were consistent with those measured using a viscometer and density meter. The third harmonic of the crystal was found to provide the closest agreement between the two measurement methods; the pure ionic liquids had the largest difference of ∼10%. In addition, 18 pure ionic liquids were tested, and for 11 of these, good-quality frequency shift and bandwidth data were obtained; these 12 all had a Newtonian response. The frequency shift of the third harmonic was found to vary linearly with square root of viscosity-density product of the pure ionic liquids up to a value of (Gη) ≈ 18 kg m, but with a slope 10% smaller than that predicted by the Kanazawa and Gordon equation. It is envisaged that the quartz crystal technique could be used in a high-throughput microfluidic system for characterizing ionic liquids.Over the past decade, the drive toward cleaner industrial processes has led to the development of ionic liquids as alternative, environmentally friendly, solvents. 16 However, the data on their physical properties as a function of chemical composition are limited, and extending the range of known data is difficult due to the expense and difficulty of producing large volumes of pure liquids for characterization.Acoustic wave microsensors, such as the quartz crystal microbalance (QCM), are widely used for studying the properties of small-volume samples of liquids, the attachment of mass from the liquid phase and in situ determination of the properties of surface coatings, such as electrodeposited polymers, during the deposition process. [17][18][19] A QCM operates by creating a highfrequency, typically 5 MHz, shear mode oscillation of the surface. When operated in a liquid environment, this surface oscillation entrains liquid and creates an oscillation, which for a Newtonian liquid decays within a penetration depth of the interface δ ) (η/ *1/2 where F and η are the density and viscosity of the liquid and f s is the resonant frequency. 20 In impedance analysis, both the resonant frequency and bandwidth, B, of the crystal are measured and are functions of the liquid properties. Bandwidth is a measure of the loss of energy and of the damping of the shear mode oscillation of the liquid close to the solid-liquid interface, and so some authors prefer to define a dissipation D ) B/f s (also equal to Q -1 ). When the liquid is Newtonian, a frequency decrease, ∆f, and a bandwidth increase, ∆B, occur in proportion to the square root of the viscosity-density product,where the specific acoustic impedance of quartz is, f o is the fundamental frequency and f s ) nf o is the overtone frequency at which the response is measured. 21,22 Thus, by verifying that changes in resonant frequency and bandwidth are correlated, such that ∆f ) -∆B/2,...
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