Block copolymer supramolecular assemblies hierarchically structured by three-beam interference laser ablation

We report the fabrication of hierarchical structures by combining bottom-up self-assembly of block copolymer supramolecular assemblies with top-down three-beam interference laser ablation methods. To fabricate the shorter length scale in the hierarchical structures, we use supramolecular assemblies (SMAs) of azobenzene compounds hydrogen bonded with poly(vinyl pyridine) blocks of polystyrene-block-poly(vinyl pyridine) block copolymers. The SMAs form phase separation nanostructures by solvent vapor annealing. The longer length scale of the hierarchical structures is fabricated by three-beam interference laser ablation on the phase separated nanostructures of the SMAs. The ablation process is induced by single laser shots with 35 ns pulse duration. Tuning of both length scales is feasible by changing the interference conditions and chemical composition of the SMAs, which enables efficient and straightforward fabrication of hierarchical photonic structures.