Enhanced order of block copolymer cylinders in single-layer films using a sweeping solidification front

A thermal method was demonstrated in an experiment for generating square-millimeter thin film samples of a cylinder-forming block copolymer (BCP) with defect densities reduced by orders of magnitude. The experiment showed further order-of-magnitude reductions in defect density by using a swept oscillatory solidification front. The simplicity of the experiment setup and facile investigation of the film's lattice structure by TM-AFM make the system ideal for experimental studies of directional crystallization. The experiment displayed a schematic of the set up used to apply such strong slow-advancing thermal gradients to thin BCP films. The substrate is an oxide-covered silicon wafer, onto which heater and sensor elements are microfabricated and the block copolymer deposited. The coupling, or lack thereof, between grain orientation and the applied static or moving temperature gradient should prove fertile area for theoretical investigation.