Dielectric breakdown strength of epoxy bimodal-polymer-brush-grafted core functionalized silica nanocomposites

Abstract

The central goal of dielectric nanocomposite design is to create a large interfacial area between the matrix polymer and nanofillers and to use it to tailor the properties of the composite. The interface can create sites for trapping electrons leading to increased dielectric breakdown strength (DBS). Nanoparticles with a bimodal population of covalently anchored molecules were created using ligand engineering. Electrically active short molecules (oligothiophene or ferrocene) and matrix compatible long poly(glycidyl methacrylate) (PGMA) chains comprise the bimodal brush. The dielectric breakdown strength was evaluated from recessed samples and dielectric spectroscopy was used to study the dielectric constant and loss as a function of frequency. The dielectric breakdown strength and permittivity increased considerably with only 2 wt% filler loading while the dielectric loss remained comparable to the reference epoxy.

Dielectric performance of high permitivity nanocomposites: impact of polystyrene grafting on BaTiO3 and TiO2

“…5,6 Numerous motifs have emerged to mitigate particle aggregation (and thus moderate field exclusion), such as aligning anisotropic fillers [7][8][9] and adopting particles with graded interfaces 10 or core-shell architectures. [11][12][13][14] Recent advances in surface initiated ATRP and Cu-catalyzed "click" chemistry have led to an increasingly diverse group of polymer grafted, hairy nanoparticles (HNPs) that feature high ε r and refractive index core plus a polymer corona with tunable structure. [15][16][17] Solution cast films of these HNPs without an accompanying polymer matrix have recently been characterized for dielectric performance.…”

On the effect of functionalizer chain length and water content in polyethylene/silica nanocomposites: Part II — Charge transport

“…Of course, functionalization also modifies the surface chemistry of the nanoparticles themselves, which leads to changes in the interactions that occur between the nanoparticles whilst in solution [13,14]. By applying two types of surface modification, some studies have even sought simultaneously to affect multiple processes [15,16]. In the work reported here, rather than seeking to manipulate nanoparticle dispersion, we focus on how modified nanoparticle surface chemistry impacts directly upon the electrical properties of the resulting nanodielectric.…”

Influence of filler/matrix interactions on resin/hardener stoichiometry, molecular dynamics, and particle dispersion of silicon nitride/epoxy nanocomposites

“…One of the key aspects of a nanofiller is its large specific surface area, which will result in a large interfacial area between the nanofiller and the encapsulating polymer. Different chemical [1], physical [2] or electrical [3] interactions can occur between the two phases, depending on the characteristics of the matrix and the nanofiller. For epoxy-based nanocomposites, nanoparticles are incorporated into the resin in its liquid state before the curing process, which allows better particle dispersion and also enables the particles to interact with the reactive resin and hardener.…”