Anatomical studies of ordered block copolymer bicontinuous networks via slice-and-view SEM reconstruction

Slice and view scanning electron microscopy (SVSEM) is an imaging technique in which the surface of a sample is imaged via SEM and then an ion beam is used to mill away a thin slice, exposing a new surface for imaging. Here we demonstrate that in block copolymer (BCP) samples exhibiting the complex tubular network double gyroid phase, SVSEM provides high resolution images of large volumes, giving access to high quality geometric information. 3D Fourier analysis of the volume images gives reciprocal space information directly without the need for scattering experiments. Using a fitting technique we identify the reciprocal lattice vectors, which gives unit cell dimensions and symmetry information. We create skeletal graphs of the gyroid networks, one-dimensional reductions of the networks consisting of bonds and nodes that capture their topology and geometry. Inter-material dividing surfaces (IMDS) are constructed; we measure the mean and Gaussian curvature distribution on the surface and compare to theoretical predictions. Finally we calculate distances between the skeletal graph and the IMDS, and the IMDS and the gyroid minimal surface, providing a measure of the degree of packing frustration in the minority and majority phase domains.