Thermo-Solvent Annealing of Polystyrene-Polydimethylsiloxane Block Copolymer Thin Films

A combined thermal and solvent vapor annealing process for block copolymer self-assembly is demonstrated. Films of cylinder-forming poly(styrene-b-dimethylsiloxane) (SD45, 45.5 kg/mol, f_PDMS = 31%) were preheated for 2 min above the glass transition temperature of both blocks, followed by immediate introduction into a chamber containing room temperature saturated vapors of toluene and n-heptane. After quenching in air, microdomains had better order than those obtained from thermal or solvent annealing alone. The short time during which the film is both heated and exposed to solvent vapor played an important role in determining the final morphology.