Polymer thin-film capacitors combine long lifetime, compactness, and mechanical flexibility, yet conventional systems suffer from low energy density, narrow operational temperature ranges, and poor thermal stability—limitations that hinder their use in high-temperature and high-power environments. Processing offers a powerful means to engineer polymer morphology and thus tailor dielectric properties. Motivated by this opportunity, this dissertation establishes a process–structure–property framework linking polymer processing, molecular orientation, and dielectric performance.

 

In the first chapter, uniaxial stretching of melt-cast poly(ethylene terephthalate) (PET) above its glass transition temperature is examined through real-time birefringence, stress, and strain measurements, revealing how oscillatory deformation drives stress-induced crystallization, amorphous-to-crystal conversion, and ultimately electrical breakdown. These results delineate the distinct roles of amorphous orientation and crystallinity in dielectric failure.

 

The second chapter maps the drying and stretching pathways of partially hydrolyzed poly(vinyl alcohol) (PVA) across molecular weight and temperature using in situ birefringence in conjunction with SAXS and WAXS. The findings demonstrate that hydrogen bonding dictates orientation, lamellar rotation, and optical anisotropy, while higher temperatures weaken intermolecular bonds, enhance chain mobility, and promote orientation.

 

In the third study, real-time drying diagnostics of solution-cast poly(ether imide) (PEI) films are correlated with dielectric breakdown behavior. Lower solids concentration, reduced molecular weight, and thinner wet films suppress skin formation, minimize interfacial field gradients, and improve breakdown strength—offering practical strategies for scalable film manufacturing.

 

The final chapter investigates a PEI synthesized from cyclohexane diamine (CHDA) and hexamethylene diamine (HMDA), where drying-induced in-plane alignment evolves through three distinct stretching regimes identified by in situ optical measurements. The oriented films exhibit strain-dependent dielectric breakdown: enhancement at low strain followed by deterioration beyond a critical stretch. These results define processing windows balancing orientation and defect control for reliable high-temperature operation.