Dielectric properties of waterborne polyelectrolyte grafted nanoparticles films sustainable energy storage media

The demand for high energy and power density storage devices necessitates the development of advanced polymer-based dielectric capacitors. Traditionally, polymer or polymer nanocomposite-based capacitors have relied on harsh solvents for processing, specifically while making film capacitors. However, the need for a sustainable future demands the use of green processing solvents, such as water. To this end, solution processable polymer grafted dielectric nanomaterials from aqueous media has attractive features of roll-to-roll processing to solve this challenging problem. In this study, we design polyelectrolyte grafted Silica nanoparticle based dielectric polymer grafted nanoparticle (PGNP) films, that can be cast from aqueous solution, as novel energy storage media. The polyelectrolyte grafted layer is critical for the aqueous processing of these hybrid nanomaterials. Our dielectric measurements show that the grafting of SiO₂ nanoparticles into PAA decreases the dielectric loss to lower than 1 at 1kHz while increasing the breakdown to above 200 V/μm. Additionally, dielectric relaxation of PAA grafted SiO₂ nanoparticle films has been studied for their temperature dependence. Here we observed a shift in the beta relaxation peak towards higher temperatures as the frequency increased. Moreover, we observed a gamma relaxation peak, in PGNP dielectric films with high polymer content, which was a frequency dependent parameter. To our knowledge, this study is the first report on the dielectric performance of PAA grafted onto SiO₂, and we will present more results on the use of water-based solutions to fine-tune the performance of PAA-functionalized PGNPs.