Block Polymer Chiral Networks*

Structures having nanoscale 3D geometries are valuable as multifunctional materials, where multi-continuous microphases can synergistically influence mechanical, optical, transport and other properties. Due to the ability to individually tailor the properties of the network(s) and matrix, for example, to create strong dielectric or impedance contrast, such spatially periodic structures are excellent for the interference of waves (electromagnetic for photonic applications and acoustic for phononic applications) that can lead to bandgaps and hence the control of wave propagation in the material. Quantitative morphological characterization of such complex geometric structures is quite challenging. Unit cell sizes range from 10-300nm with corresponding feature sizes on the 2-50nm scale. In order to understand optical properties for periodic chiral phases such as the single gyroid, we need to be able to measure the local features such as the set of dihedral angles between successive nodes in the network. 3D tomographic reconstructions can be done by slice and view scanning electron microscopy to allow access to the network connectivity and geometry.