Aaron F. Baldwin

Rationally designed polyimides for high-energy density capacitor applications.

Development of new dielectric materials is of great importance for a wide range of applications for modern electronics and electrical power systems. The state-of-the-art polymer dielectric is a biaxially oriented polypropylene (BOPP) film having a maximal energy density of 5 J/cm(3) and a high breakdown field of 700 MV/m, but with a limited dielectric constant (∼2.2) and a reduced breakdown strength above 85 °C. Great effort has been put into exploring other materials to fulfill the demand of continuous miniaturization and improved functionality. In this work, a series of polyimides were investigated as potential polymer materials for this application. Polyimide with high dielectric constants of up to 7.8 that exhibits low dissipation factors (<1%) and high energy density around 15 J/cm(3), which is 3 times that of BOPP, was prepared. Our syntheses were guided by high-throughput density functional theory calculations for rational design in terms of a high dielectric constant and band gap. Correlations of experimental and theoretical results through judicious variations of polyimide structures allowed for a clear demonstration of the relationship between chemical functionalities and dielectric properties.

Poly(dimethyltin glutarate) as a Prospective Material for High Dielectric Applications

Poly(dimethyltin glutarate) is presented as the first organometallic polymer, a high dielectric constant, and low dielectric loss material. Theoretical results correspond well in terms of the dielectric constant. More importantly, the dielectric constant can be tuned depending on the solvent a film of the polymer is cast from. The breakdown strength is increased through blending with a second organometallic polymer.

Rational design and synthesis of polythioureas as capacitor dielectrics

Rational strategies combining computational and experimental procedures accelerate the process of designing and predicting properties of new materials for a specific application. Here, a systematic study is presented on polythioureas for high energy density capacitor applications combining a newly developed modelling strategy with synthesis and processing. Synthesis was guided by implementation of a high throughput hierarchical modelling with combinatorial exploration and successive screening, followed by an evolutionary structure search based on density functional theory (DFT). Crystalline structures of polymer films were found to be in agreement with DFT predicted results. Dielectric constants of ∼4.5 and energy densities of ∼10 J cm−3 were achieved in accordance with Weibull characteristic breakdown fields of ∼700 MV m−1. The variation of polymer backbone using aromatic, aliphatic and oligoether segments allowed for tuning dielectric properties through introduction of additional permanent dipoles, conjugation, and better control of morphology.

Effect of Incorporating Aromatic and Chiral Groups on the Dielectric Properties of Poly(dimethyltin esters)

High-dielectric constant materials are critical for numerous applications such as photovoltaics, photonics, transistors, and capacitors. There are numerous polymers used as dielectric layers in these applications but can suffer from having a low dielectric constant, small band gap, or ferroelectricity. Here, the structure-property relationship of various poly(dimethyltin esters) is described that look to enhance the dipolar and atomic polarization component of the dielectric constant. These polymers are also modeled using first principles calculations based on density functional theory (DFT) to predict such values as the total, electronic, and ionic dielectric constant as well as structure. A strong correlation is achieved between the theoretical and experimental values with the polymers exhibiting dielectric constants >4.5 with dissipation on the order of 10(-3) -10(-2) .