Cold zone annealing (CZA) is a thermal treatment involving pulling a thin block copolymer (BCP) film over a heated region having a temperature significantly above the glass-transition temperature, but well below the film order-disorder temperature. We investigate the potential of CZA for controlling defects in block copolymer thin films and as a platform for studying defect formation, annihilation, and dynamics. The dramatic increase in orientational order obtained by CZA relative to conventional oven annealing methods is attributed to the large in-plane mobility gradient that accompanies the in-plane temperature gradient in glassy polymeric materials. This mobility gradient leads to a progressive alignment of cylinders in the sample pulling direction and presumably to a substantial modification of the defect annihilation dynamics during grain growth.
Citation: Nano Letters
Pub Type: Journals
block copolymers, defects, order, orientation, zone annealing