Session L36 - General Poster Session II.
POSTER session, Wednesday morning, March 22
Exhibit Hall, MCC
We have investigated two dimensional pattern coarsening dynamics with a block copolymer which microphase separates into spheres. The system consisted of a single layer of polystyrene spheres in a polyethylene-alt-polypropylene matrix (PS-PEP) on a substrate and was studied by hot stage atomic force microscopy (AFM). By performing Delaunay triangulation, we quantitatively demonstrate a high density of free dislocations and a relatively low density of free disclinations. By obtaining sequential AFM images as a function of annealing time, we have tracked the grain growth and defect motion. During annealing, the correlation length saturates at temperature dependent values, resulting in pinned grain boundaries consisting of a high density of dislocations and disclinations. Increasing the annealing temperature decreases barriers to motion, depinning defects from grain boundaries and resulting in a better ordered pattern with fewer grain boundaries.