Nanolaminates: Increasing Dielectric Breakdown Strength of Composites

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• 作者：Scott P. Fillery ; Hilmar Koerner ; Lawrence Drummy ; Erik Dunkerley ; Michael F. Durstock ; Daniel F. Schmidt ; Richard A. Vaia
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2012
• 出版时间：March 28, 2012
• 年：2012
• 卷：4
• 期：3
• 页码：1388-1396
• 全文大小：420K
• 年卷期：v.4,no.3(March 28, 2012)
• ISSN：1944-8252

文摘

Processable, low-cost, high-performance hybrid dielectrics are enablers for a vast array of green technologies, including high-temperature electrical insulation and pulsed power capacitors for all-electric transportation vehicles. Maximizing the dielectric breakdown field (E_BD), in conjunction with minimization of leakage current, directly impacts system performance because of the field鈥檚 quadratic relationship with electrostatic energy storage density. On the basis of the extreme internal interfacial area and ultrafine morphology, polymer-inorganic nanocomposites (PNCs) have demonstrated modest increases in E_BD at very low inorganic loadings, but because of insufficient control of the hierarchal morphology of the blend, have yielded a precipitous decline in E_BD at intermediate and high inorganic volume fractions. Here in, we demonstrate that E_BD can be increased up to these intermediate inorganic volume fractions by creating uniform one-dimensional nanocomposites (nanolaminates) rather than blends of spherical inorganic nanoparticles and polymers. Free standing nanolaminates of highly aligned and dispersed montmorillonite in polyvinyl butyral exhibited enhancements in E_BD up to 30 vol % inorganic (70 wt % organically modified montmorillonite). These relative enhancements extend up to five times the inorganic fraction observed for random nanoparticle dispersions, and are anywhere from two to four times greater than observed at comparable volume fraction of nanoparticles. The breakdown characteristics of this model system suggested a trade-off between increased path tortuosity and polymer-deficient structural defects. This implies that an idealized PNC morphology to retard the breakdown cascade perpendicular to the electrodes will occur at intermediate volume fractions and resemble a discotic nematic phase where highly aligned, high-aspect ratio nanometer thick plates are uniformly surrounded by nanoscopic regions of polymer.

Keywords:

dielectric nanocomposite; nanolaminate; layered silicate; permittivity; dielectric breakdown; energy storage