Macrophase Separation Using Block Copolymer Blends

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2014-04-15
Authors
Philiph, Rachel
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Massachusetts Institute of Technology
Abstract

Diblock copolymers (BCP) have been used in the past to create nano-scale features in thin films. Films of a single BCP have been successfully controlled using templates, but produce features with only one morphology or one size. This limits the complexity of features and range of possible applications. By using blends of BCPs with immiscible blocks, it is hypothesized that macrophase-separated thin films can be created. A blend of poly(styrene-b-dimethylsiloxane) and poly(styrene-b-ferrocenylsilane) (PS-b-PDMS/PS-b-PFS) block copolymer was spin coated on a silicon substrate functionalized with polystyrene. Samples were then annealed by solvents controlled by a mass flow system. Samples were characterized using scanning electron microscopy (SEM). Through experimentation, film thickness, solvents, and annealing times were optimized. A film thickness of about 40 nm, solvents to selectively swell each block, and an annealing time of 12 hours most effectively achieved macrophase separation. In the future, chemical and physical templating will be used to control the placement and morphology of regions. This work could result in complex features that have not previously been possible.

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