Ultraconfined block copolymer films present nonbulk structures that are highly sensitive to film thickness and are strongly influenced by the wetting properties of the substrate. Here, we describe the self-assembly of bottlebrush block copolymers with varying side-chain lengths on different types of substrates. Our results show a pronounced influence of the nature of the substrate on the self-assembled morphology and the surface patterns that evolve during solvent-vapor annealing. In particular, we observe by experiments and simulations a transient, substrate-driven morphology of cylinder-like structures obtained in films of doubly symmetric (i.e., the backbone and side chains) bottlebrush block copolymers despite the general tendency of these polymers to form lamellar structures. The insights gained from this study highlight the ability to use the substrate chemistry for inducing the formation of unique morphologies in bottlebrush block copolymer films.
Bibliographical noteFunding Information:
Financial support for this work was provided by the Israel Science Foundation (grant number 229/17), the National Science Foundation (DMR-1709371), and Deutsche Forschungsgemeinschaft (MU 1674/16-2).
The authors thank Elina Ploshnik for a sample of the PS–OH brush and Yousef Farraj for assistance with contact angle measurements. Y.A. thanks the Hebrew University for a doctoral fellowship. M.M. acknowledges computing time granted by the John von Neumann Institute for Computing (NIC), Germany, provided on the supercomputer JUWELS at the Jülich Supercomputing Center (JSC) as well as computational resources at HLRN Göttingen/Berlin and GWDG Göttingen.
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