(Color online) Schematic of spotted chemical patterns with a range of density multiplication factors and subsequent directed assembly of block copolymer-homopolymer-homopolyer ternary blend films.
(a) Top-down SEM images of the directed assembly of thin films of ternary blends on chemical patterns with a range of density multiplication factors. The homopolymer fractions in the blend were 0, 0.2, and 0.4. The distribution graphs for the assembled PMMA cylinder size at the top surface were computed from top-down SEM images of a 2:1 directed assembly, with (b) and (c) films.
(Color online) Effect of chemical pattern spot diameter on domain diameter at the free surface of the assembled ternary blend films . (a) Top-down SEM images of the ternary blends directed to assemble on chemical patterns with a 2:1 assembly ratio. The SEM images were taken from the edge of the patterned area and show the assembled blend above both the unpatterned substrate and the patterned substrate, denoted by the circles above the SEM image. (b) Graph of on the chemical patterns with different values of . The error bars correspond to the 1 standard deviation for each case. The filled (blue) symbols on the graph denote the size of the domains directly above spots on the chemical pattern, and the open (red) symbols denote the size of the domains that are above the background imaging layer. The star symbol denotes the assembled domains on a 1:1 chemical pattern with no density multiplication, for the sake of comparison.
(Color online) Monte Carlo simulation results showing the influence of the prepattern on the domain shape. Each color map is a cross-section taken at height , 3/8, 5/8, or , where is the film thickness. The color indicates the local composition from the PS-rich areas (red or dark) to PMMA-rich areas (blue or light). Below each column, the type of pattern and the spot radius are indicated. The homopolymer volume fraction was .
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