Dielectric research, focus

It follows that many of the most exciting dielectric elastomer materials were discovered via exploratory testing. New formulations of commercially available elastomers are continually being developed and may well be worth exploring. However it is expected that research focusing on developing materials specifically for dielectric elastomer purposes from focused and directed research will provide the best candidates for improved performance in the years to come. 

Our research using the CCS approach has focused on the discovery of new dielectric thin films. This example illustrates the power of this approach and key considerations in utilizing high throughput synthesis and screening approaches. A variety of other problems appear well matched to such combinatorial-style methods. A few of these are discussed briefly below, touching on both experimental challenges and research opportunities. 

Alternative polymers that have certain advantages over polyimides have also been introduced they include poly(phenylquinoxaline), poly(phenylquinoline), and poly(benzocyclobutenes) (PBCBs) (93,116). The PBCBs have a low curing temperature (250 °C), low dielectric constant (2.6), low dissipation factor (0.0045), and low moisture absorption (0.3%) The development of specialty polymers for packaging and high-density interconnections will continue to be an active area of research as polymer manufacturers focus on the needs of the microelectronic industry. 

Some indirect experimental evidence exists for the liquid-liquid critical point hypothesis from the changing slope of the melting curves, which was observed for different ice polymorphs (30, 31). A more direct route to the deeply supercooled region, by confining water in nanopores to avoid crystallization, has been used more recently by experimentalists. These researchers applied neutron-scattering, dielectric, and NMR-relaxation measurements (32-35). These studies focus on the dynamic properties and will be discussed later. They indicate a continuous transition from the high to the low-density liquid at ambient pressure. The absence of a discontinuity in this case could be explained by a shift of the second critical point to positive pressures in the confinement. This finding correlated with simulations, which yield such a shift when water is confined in a hydrophilic nanopore (36). 

Widespread application of near-critical and supercritical CO2 to process industries has been hindered up to now by a very weak solvent strength. In many applications where the physical and environmental properties of CO2 would otherwise be favorable, the fact that CO2 cannot dissolve or carry the required solute has blocked its application. One reason being the low dielectric constant (1.4-1.5) compared to the typical organic solvents (2.0. 0). The very hydrophobic nature of CO2 makes it a bad solvent for many solutes. Improving the solvent strength has been the focus of research in recent decades. 

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