Selective solvent vapor induced self-assembly of silicon-containing bottlebrush block copolymer thin films to generate mesoporous silicon oxide patterns

Abstract

Bottlebrush block copolymers (BBCPs) are intriguing architectures that can produce various anisotropic nanostructures dictated by the composition, length of the backbone and the lengths of side-chains. Here, we develop a facial approach toward ordered inorganic silicon oxide patterns and particles on substrates by solvent vapor induced thin film self-assembly of anisotropic bottlebrush block copolymers (BBCP) containing polydimethylsiloxane (PDMS) and polystyrene (PS) side chains. The in-plane cylindrical or stripes-like, spherical, and ordered porous morphologies as well as Janus particles-like morphology were fabricated on the substrate through solvent vapor annealing (SVA). The Janus particle-like morphology consisting of PS heads inserted in PDMS heads were directed to produce meso-to macroporous silicon oxide bowls after oxygen plasma etching. The effects of the solvent vapor on the molecular geometry and morphology of the BBCPs were described, and the influence of the backbone length on the self-assembly behavior of the thin film were discussed. This work demonstrates that silicon-containing BBCPs with a native etch contrast and a large difference in solubility parameters are potential candidates to generate ordered silicon oxide templates of different geometries with periodicity 80–150 nm providing access to length scales larger than linear block copolymers.