The objective of this project is to carry out research in addressing the Navy's future needs of energy storage and regulation as well as acoustic sensing and transduction. Scalable dielectric material and film technologies are desired with significantly increased storage capacity at the device level and use temperature of 150 C or higher while maintaining the high cycle efficiencies/low losses of current state-of-the-art capacitors. Polymer dielectrics and nanocomposites based on them have great potential to meet the Navy's future pulse power, power conditioning, and energy storage needs. Polymers, owing to light weight, acoustic impedance matching to water, pliability, and easy fabrication into complicated shapes, are attractive for Navy acoustic transduction applications. However, the low piezoelectric coefficients and low electromechanical coupling severely limit their Navy applications. Hence, another objective is to develop approaches for ferroelectric polymers reaching piezo-performance comparable to or even better than that of PZTpiezoceramics. Ferroelectric polymers in which the dielectric response such as dielectric constant K and polarization P can be tuned while maintaining high breakdown strength Eb are of great interest to Navy dielectric and acoustic transduction needs. In pasta few years under ONR support, we have discovered a new class of dielectric polymer nanocomposites: dilute nanocomposites, in whichnanofillers at ultralow volume loading, through nano-interface effects, generate marked enhancement in the dielectric performance of high temperature polymers. We further showed that in suitably selected polymer blends, the nano-interfacial effects between the two polymers can be exploited to tune the conformation and packing behavior of polymer chains which lead to marked enhancement in K orEb. In this ONR program, we propose to carry out a systematical investigation and develop fundamental understanding of the mechanisms which underpin the observed enhancement in this new class of dielectric polymer nanocomposites, especially the dilute nanocomposites in which both K and Eb are enhanced. We propose to investigate the topological effects of nanofillers (beyond 0D nanofillers) in the dilute nanocomposites, polymer blends and dilute nanocomposites with polymer blends as the matrix. Nano-probes will be employed to characterize the spatial variation of dielectric and other properties in composite films. Making use of these nanocomposites, we will also investigate how to mitigate the conduction losses at high electric field and high temperature and consequently enhance the dielectric breakdown strength and discharge/charge efficiency. In viewing of large family of the commercially available high temperature dipolar polymers with different molecular structures, this class of dielectric polymer nanocomposites open a totally new approach to realize scalable dielectric polymers with high operating temperature, high energy density, low loss and low cost for Navy and DoD applications. The science developed in this ONR program will pave the way for generating dielectric polymers and devices with unprecedent high performance. In the ONR dielectric program, it was also discovered that proper defects modifications in P(VDF-TrFE) based relaxor polymers can lead to giant electromechanical coupling and high piezoelectric responses under ultra-low electric fields. We propose in this program to investigate these effects further and develop the understanding of how these defects affect various polarization responses and electromechanical cross coupling in P(VDF-TrFE) based relaxor polymers.
|Effective start/end date||2/1/23 → …|
- U.S. Navy: $450,000.00