Center for Functional Nanomaterials Seminar

Block-copolymers form well-defined structures at the nanometer lengthscale, and represent a model self-assembling system with real applications. The morphology, orientation, and degree of order resulting from assembly is sensitive to a variety of preparation parameters, including annealing time and temperature; solvent exposure; substrate surface energy; application of electric fields; etc. This talk will present strategies for controlling the order in block-copolymers, and discuss some of the measurement challenges that arise. In particular, the use of inherently defective and tunable substrate layers is shown to provide a robust route to controlling orientation. Further, a moving thermal zone can alter ordering kinetics, and bias orientation. Using combinatorial samples and probing with atomic force microscopy, neutron reflectivity, and scattering techniques, the order in these systems can be quantified. Specifically, the use of Small-Angle Neutron Scattering in a rotation mode (RSANS) and Grazing-Incidence Small-Angle X-ray Scattering (GISAXS) will be highlighted. Measurements made through the thermal zone show greatly enhanced ordering kinetics, as compared to conventional oven annealing, and constrain models that attempt to explain the phenomenon.