**5. Outlook**

Researchers have achieved some progress in developing polyimides for capacitor dielectrics targeted for operating temperature above 150°C, but there is still major room for improvement. There is a promising new strategy of combining polymer synthesis and computational techniques (e.g., computational quantum mechanics and molecular dynamics) to synergistically search the material space for polymers

with desirable material properties (dielectric constant, glass transition temperature, etc.) for capacitor applications. The ultimate goal is to develop synthesis pathways for polymers that are as close as possible to those "discovered" through computational methods [85–89]. The synergy comes in (i) directing the focus of synthesis and (ii) providing data which simplifies characterization of synthesized polymers through computation of likely crystalline structures (with relative energy differences), IR spectra, and NMR spectra. Work in this area is still relatively limited in that some critical properties cannot be estimated through computational methods, including thermal conductivity, dielectric breakdown field (other than intrinsic), and dielectric loss at frequencies of practical interest (in the kHz region). These deficiencies in the present state of the art result in the approach being somewhat "hit or miss," but with greater guidance than conventional trial and error approaches. For example, a computational approach uncovered a new chemistry based on organotin esters that was subsequently synthesized and shown to provide greater dielectric constant than is normally available from organic polymers while maintaining a reasonable band gap [90]. This interplay between predictive modeling and synthetic chemistry will become increasingly productive with integration of additional material properties into the explored materials space, and polyimides will certainly be one material class of continued interest to researchers.
