Structure-Property Relationships Nanostructured Dielectric Materials

The unprecedented control over organic-inorganic hybrid nanomaterial structure afforded by polymer synthesis and functionalization techniques provides a toolbox for materials property design. For applications such as high energy density dielectrics, a high volume fraction of inorganic material is desired while maintaining an appropriate interparticle separation distance, thus avoiding percolation which leads to dielectric breakdown. We have functionalized the surface of oxide (BaTiO3, TiO2, SiO2) nanoparticles with polymers (PS, PMMA) of controlled molecular weight and purified the resulting hybrid nanoparticles so that no unbound polymer remained. The resulting nanoparticles were assembled into films which showed increased dielectric constant with increasing volume fraction of inorganic, while maintaining their dielectric breakdown strength. Finally, 3D electron tomography and small angle X-ray scattering were used to develop structure-property relationships which showed that control of both the nano-structure (interparticle separation distance) and the meso-structure (void size) are critical to achieving the desired material properties.