Reversible Morphology Locking via Metal Infiltration in a Block Copolymer

Metal infiltration from an acid solution of a metal precursorintothe poly(2-vinylpyridine) (P2VP) microdomains of a polystyrene-b-P2VP block copolymer is shown to reduce the uptake ofsolvent vapor during a subsequent solvent annealing process, lockingthe morphology of the self-assembled microdomains. The amount of metal,here Pt, incorporated into the P2VP increases with both metal precursor[PtCl4](2-) and hydrochloric acid concentrations,reaching 0.83 Pt atom per pyridine unit. The metal is then exfiltratedusing a KOH + ethylenediamine-tetraacetic acid disodium saltdihydrate (Na(2)EDTA) complexing solution, which restoressolvent uptake and unlocks the morphology. The reversibility of themetal infiltration and morphology locking is demonstrated in a multistageannealing process and is confirmed for Fe as well as Pt. Reversiblelocking and unlocking of block copolymer microdomain morphologiesexpand their utility for nanofabrication processes by allowing themorphology to be fixed during subsequent process steps.

Automated summary

Infiltration of metal precursor solution into P2VP microdomains reduces solvent vapor uptake, locking the morphology. Metal content in P2VP, such as Pt, increases with precursor and acid concentrations. Metal is then exfiltrated using a complexing solution, restoring solvent uptake and unlocking the morphology. The reversible locking and unlocking of block copolymer microdomain morphologies expand their utility for nanofabrication processes.