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Novel Superdielectric Materials: Aqueous Salt Solution Saturated Fabric.

ABSTRACT: The dielectric constants of nylon fabrics saturated with aqueous NaCl solutions, Fabric-Superdielectric Materials (F-SDM), were measured to be >10⁵ even at the shortest discharge times (>0.001 s) for which reliable data could be obtained using the constant current method, thus demonstrating the existence of a third class of SDM. Hence, the present results support the general theoretical SDM hypothesis, which is also supported by earlier experimental work with powder and anodized foil matrices: Any material composed of liquid containing dissolved, mobile ions, confined in an electrically insulating matrix, will have a very high dielectric constant. Five capacitors, each composed of a different number of layers of salt solution saturated nylon fabric, were studied, using a galvanostat operated in constant current mode. Capacitance, dielectric constant, energy density and power density as a function of discharge time, for discharge times from ~100 s to nearly 0.001 s were recorded. The roll-off rate of the first three parameters was found to be nearly identical for all five capacitors tested. The power density increased in all cases with decreasing discharge time, but again the observed frequency response was nearly identical for all five capacitors. Operational limitations found for F-SDM are the same as those for other aqueous solution SDM, particularly a low maximum operating voltage (~2.3 V), and dielectric "constants" that are a function of voltage, decreasing for voltages higher than ~0.8 V. Extrapolations of the present data set suggest F-SDM could be the key to inexpensive, high energy density (>75 J/cm³) capacitors.

SUBMITTER: Phillips J

PROVIDER: S-EPMC5457209 | biostudies-other | 2016 Nov

REPOSITORIES: biostudies-other

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Project description:It has been previously demonstrated that copper-based metal-organic frameworks (MOFs) accelerate formation of the therapeutically active molecule nitric oxide (NO) from S-nitrosothiols (RSNOs). Because RSNOs are naturally present in blood, this function is hypothesized to permit the controlled production of NO through use of MOF-based blood-contacting materials. The practical implementation of MOFs in this application typically requires incorporation within a polymer support, yet this immobilization has been shown to impair the ability of the MOF to interact with the NO-forming RSNO substrate. Here, the water-stable, copper-based MOF H3[(Cu4Cl)3-(BTTri)8] (H3BTTri = 1,3,5-tris(1H-1,2,3-triazol-5-yl)benzene), or Cu-BTTri, was incorporated within the naturally derived polysaccharide chitosan to form membranes that were evaluated for their ability to enhance NO generation from the RSNO S-nitrosoglutathione (GSNO). This is the first report to evaluate MOF-induced NO release from GSNO, the most abundant small-molecule RSNO. At a 20 μM initial GSNO concentration (pH 7.4 phosphate buffered saline, 37 °C), chitosan/Cu-BTTri membranes induced the release of 97 ± 3% of theoretical NO within approximately 4 h, corresponding to a 65-fold increase over the baseline thermal decomposition of GSNO. Furthermore, incorporation of Cu-BTTri within hydrophilic chitosan did not impair the activity of the MOF, unlike earlier efforts using hydrophobic polyurethane or poly(vinyl chloride). The reuse of the membranes continued to enhance NO production from GSNO in subsequent experiments, suggesting the potential for continued use. Additionally, the major organic product of Cu-BTTri-promoted GSNO decomposition was identified as oxidized glutathione via mass spectrometry, confirming prior hypotheses. Structural analysis by pXRD and assessment of copper leaching by ICP-AES indicated that Cu-BTTri retains crystallinity and exhibits no significant degradation following exposure to GSNO. Taken together, these findings provide insight into the function and utility of polymer/Cu-BTTri systems and may support the development of future MOF-based biomaterials.

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Novel Superdielectric Materials: Aqueous Salt Solution Saturated Fabric.

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