Enhanced Dielectric Permittivity of Optimized Surface Modified of Barium Titanate Nanocomposites.

High permittivity polymer-ceramic nanocomposite dielectric films take advantage of the ease of flexibility in processing of polymers and the functionality of electroactive ceramic fillers. Hence, films like these may be applied to embedded energy storage devices for printed circuit electrical boards. However, the incompatibility of the hydrophilic ceramic filler and hydrophobic epoxy limit the filler concentration and therefore, dielectric permittivity of these materials. Traditionally, surfactants and core-shell processing of ceramic fillers are used to achieve electrostatic and steric stabilization for adequate ceramic particle distribution but, questions regarding these processes still remain. The purpose of this work is to understand the role of surfactant concentration ceramic particle surface morphology, and composite dielectric permittivity and conductivity. A comprehensive study of barium titanate-based epoxy nanocomposites was performed. Ethanol and 3-glycidyloxypropyltrimethoxysilan surface treatments were performed, where the best reduction in particle agglomeration, highest value of permittivity and the lowest value of loss were observed. The results demonstrate that optimization of coupling agent may lead to superior permittivity values and diminished losses that are ~2-3 times that of composites with non-optimized and traditional surfactant treatments.

Investigation of Piezoelectricity and Resistivity of Surface Modified Barium Titanate Nanocomposites.

Polymer-ceramic nanocomposite piezoelectric and dielectric films are of interest because of their possible application to advanced embedded energy storage devices for printed wired electrical boards. The incompatibility of the two constituent materials; hydrophilic ceramic filler, and hydrophobic epoxy limit the filler concentration, and thus, their piezoelectric properties. This work aims to understand the role of surfactant concentration in establishing meaningful interfacial layers between the epoxy and ceramic filler particles by observing particle surface morphology, piezoelectric strain coefficients, and resistivity spectra. A comprehensive study of nanocomposites, comprising non-treated and surface treated barium titanate (BTO), embedded within an epoxy matrix, was performed. The surface treatments were performed with two types of coupling agents: Ethanol and 3-glycidyloxypropyltrimethoxysilan. The observations of particle agglomeration, piezoelectric strain coefficients, and resistivity were compared, where the most ideal properties were found for concentrations of 0.02 and 0.025. This work demonstrates that the interfacial core-shell processing layer concentration influences the macroscopic properties of nanocomposites, and the opportunities for tuning interfacial layers for desirable characteristics of specific applications.