Morphology determination of defect-rich diblock copolymer films with time-of-flight grazing-incidence small-angle neutron scattering

The complex nanomorphology of a defect-rich deuterated poly(styrene-block- methyl methacrylate), P(S-b-MMAd), diblock copolymer film is determined with a combination of grazing-incidence small-angle neutron scattering (GISANS) and time-of-flight (TOF) mode. TOF-GISANS enables the simultaneous performance of several GISANS measurements that differ in wavelength. The resulting set of GISANS data covers different ranges of the scattering vector and has different scattering depths. Thus surface-sensitive and bulk-sensitive measurements can be performed simultaneously. The P(S-b-MMAd) film exhibits a lamellar microphase separation structure, which because of the defects is arranged into small, randomly oriented grains, composed of four-five lamellar repetitions. In the near-surface region, the lamellar structure is oriented parallel to the substrate, which explains the smooth surface found with atomic force microscopy.